Biochemistry Exam 2

purification strategy

A characterized protein can be designed to contain a hexahistidine tag that will then bind to a nickel affinity column by immobilized metal affinity chromatography (IMAC) while an unknown protein will be separated based on inherent properties of the protein identified empirically.

protein source

A characterized protein can be transformed into a cell system for large-scale production while an unknown protein will need to be sourced from its native biological source.

enzymatic bioassay

A characterized protein can be transformed to contain a marker such as a green fluorescent protein (GFP) that can be visualized under blue light, while an unknown protein will need to be detected based on the inherent-enzymatic activity of the protein.

bind, conformational

Allosteric regulators bind where and what do they do? Allosteric sites allow effectors to ___________ to the protein, often resulting in a _______________________ change involving protein dynamics.

effector

Allosteric regulators bind where and what do they do? Bind at an ______________________ molecule at a site other than the enzyme's active site The site to which the ______________________ binds is termed the allosteric site or regulatory site.

activators, inhibitors

Allosteric regulators bind where and what do they do? Effectors that enhance the protein's activity are referred to as allosteric ____________________, whereas those that decrease the protein's activity are called allosteric ____________________.

catalytic, primary

Amino acids that are far apart in the amino acid sequence of an enzyme can be essential for the enzyme's catalytic activity. What does this suggest about the enzyme's active site? (Select all that apply.) The amino acids are located at parts of the enzyme essential for its ________________ activity, such as at the active site or at sites controlling the enzyme's structure. The 3-D location of specific amino acids is not determined by ________________ structure. This result suggests that the active site is made up of amino acid residues from different portions of primary sequence.

tryptophan, aspartic

An amino acid mixture consisting of alanine, tryptophan, and aspartic acid is to be separated by normal phase HPLC. The stationary phase is polar and the mobile phase is a nonpolar solvent. The first amino acid to be eluted will be ____________________. The last amino acid to be eluted will be ________________ acid.

aspartic, positively, alanine, lysine

An amino acid mixture consisting of lysine, aspartic acid, and leucine is to be separated by ion-exchange chromatography, using a cation-exchange resin at pH 3.5, with the eluting buffer at the same pH. The first amino acid to be eluted will be _________________ acid. The other two amino acids will remain on the column because they are ____________________ charged. In order to elute these two proteins from the column it will be necessary to Raise the pH first to 7 to elute _____________, and then raise it to 11 to elute ___________.

enhanced

An enzyme catalyzes the formation of ATP from ADP and phosphate ion. What is its effect on the rate of hydrolysis of ATP to ADP and phosphate? The rate of the reaction ATP → ADP + phosphate will be _____________________ by the same factor as the rate for ADP + phosphate → ATP.

higher, not, catalyst

An enzyme that normally functions in the stomach and one that is normally found in the blood catalyze their reactions at the same rate under optimal conditions. Equal concentrations of both enzymes are placed in solutions with pH = 7. How does the rate of the stomach enzyme reaction compare with the rate of the reaction catalyzed by the blood enzyme? The blood enzyme reaction rate is _________________. A stomach enzyme that functions normally at a very low pH will probably ______ function at pH 7. Blood has an approximate pH of 7.4, so at pH 7 the blood enzyme is close to its optimal pH conditions and will be able to function as a _______________.

Feedback

An inhibitor is the product of a reaction further along in a sequence of reactions. What kind of regulation is this? ________________________ control

decreases

Any change from the optimal temperature range __________________ enzyme activity.

Cyanogen bromide, trypsin, Chymotrypsin

Assume that you are getting ready to do an amino acid sequencing experiment on a protein containing 100 amino acid residues, and amino acid content analysis produces the data given in the table. Which of the chemicals or enzymes normally used for cutting proteins into fragments would be the least useful to you? Rank order the chemicals or enzymes from least to most useful. ______________________ ________________, __________________, ___________________

stable, denaturation, less

Because the substrate binds to the enzyme's active site, the presence of substrate in the solution will make the enzyme more _______________, and thus less susceptible to ___________________________. This happens because the free energy of the enzyme-substrate complex is __________ than the free energy of unbound enzyme plus unbound substrate.

lyase

Bond breaking with double bond formation; e.g. aldolases and decarboxylases

hydrolase

Bond breaking with the addition of water; e.g. serine protease; glucose-6-phosphatase

no, concentration

Can inhibition be overcome by large concentrations of substrate? ______, unlike competitive inhibition, noncompetitive inhibitors will bind to the enzyme regardless of the _______________________ of S. The presence of more S cannot completely "wash out" the effect of the inhibitor.

no, decreases

Chemical reaction rates generally increase with increasing temperature. Is this true for reactions involving enzymes? _______, The reaction rate increases with temperature, but then __________________ when the molecular conformation of the enzyme is affected at high temperatures.

isomerase

Conversion to an isomer of the molecule; e.g. triose phosphate isomerase and phosphoglucose isomerase

ligases

Coupling of two molecules; e.g. pyruvate carboxylase; DNA ligase

nucleophilic

Covalent catalysis assists with what type of reactions? In this reaction the enzyme contains a reactive group, usually a _________________________ residue which reacts with the substrate through a _________________________ attack.

amino, carboxylic, loss, amide

Describe the chemical reaction for peptide bond formation. A terminal ____________ group attacks a terminal _________________ acid group on an amino acid residue resulting in the __________ of water and the formation of an ____________ bond.

increase

Design an experiment to purify protein X on an anion-exchange column. Protein X is contained in a protein homogenate at pH 7. Protein X has an isoelectric point of 8.5. Indicate which of the items on the right are necessary and in which order to apply them to the sample. first technique to apply: ________________ the pH of the protein solution to 10.0

collect

Design an experiment to purify protein X on an anion-exchange column. Protein X is contained in a protein homogenate at pH 7. Protein X has an isoelectric point of 8.5. Indicate which of the items on the right are necessary and in which order to apply them to the sample. fourth technique to apply: _______________ the fraction containing protein X that comes out during the previous step

proper

Design an experiment to purify protein X on an anion-exchange column. Protein X is contained in a protein homogenate at pH 7. Protein X has an isoelectric point of 8.5. Indicate which of the items on the right are necessary and in which order to apply them to the sample. second technique to apply: pour the protein homogenate at its ________________ pH through the coumn

salt, low, high

Design an experiment to purify protein X on an anion-exchange column. Protein X is contained in a protein homogenate at pH 7. Protein X has an isoelectric point of 8.5. Indicate which of the items on the right are necessary and in which order to apply them to the sample. third technique to apply: pour a ___________ gradient from _______ salt concentration to __________ salt concentration through the column

no, saturated

Do increasing enzyme and substrate concentrations affect enzyme activity in the same way? ________, increasing substrate concentration increases reaction rate, but at a certain concentration, the enzyme becomes ____________________ with substrate and the rate becomes constant

noncompetitive, not

Does a noncompetitive inhibitor bind to the active site of the enzyme it inhibits? No, A ____________________________ inhibitor binds to the enzyme in a location that is ________ the active site.

increase, decreases, decreases, increases

Does an increase in KI' lead to an increase or a decrease in the reaction rate? ________________, The slope ________________, which means 1/ν ________________ and ν ________________. Note that as KI' increases, the fraction of inhibitor-bound enzyme decreases. This frees more E to bind with S

decreases, increases, increases, decreases

Does an increase in [I] lead to an increase or a decrease in the reaction rate? ________________, The slope ________________, which means 1/ν ________________ and ν ________________. This makes sense because more I is available and binds to the enzyme. Less E is available to bind with S to form ES, which reacts to form P.

protein purity/quantification

ELISA or Western blot can be used for a characterized protein, while an unknown protein will need to be detected by a non-specific protein stain such as Coomassie blue or silver staining and quantified by a stain reagent such as a Bradford Assay

competitive

Enzyme inhibition can be overcome under some, but not all, conditions. Under what conditions can inhibition be overcome? A _____________________ inhibitor can always be overcome by the addition of enough substrate, while a noncompetitive inhibitor can never be overcome.

Peptide

Enzymes undergo a decrease in catalytic efficiency in the presence of excess temperature, but can regain this efficiency once temperature returns to normal: this suggests that increased temperature does not disrupt which of the following aspects of enzyme structure? __________________ bonds

kinetic, Brownian, maximum

Explain why enzyme activity increases with temperature and then precipitously drops off.? The relatively graduate increase in enzyme activity with greater temperature is due to greater _________________ energy of the system and greater _________________ movement resulting in greater product formation. Above some ___________________ temperature the enzyme begins to degrade, and enzyme activity drops off precipitously.

polymer

Gel electrophoresis separate polypeptides or polynucleotides based on what physical property? Size of the ________________

increases, unchanged

How can competitive and noncompetitive inhibition be distinguished in terms of KM? The apparent value of KM __________________ with a competitive inhibitor, while it remains ______________________ with a noncompetitive inhibitor.

unchanged, decreases

How can competitive and noncompetitive inhibition be distinguished in terms of Vmax? The Vmax remains ____________________ with a competitive inhibitor, while it __________________ with a noncompetitive inhibitor.

charge, weight

How does 2-dimensional gel electrophoresis work? Resolution initially by ________________ (isoelectric focusing) and then attached to SDS-PAGE for molecular ________________ separation. By this method, over 1,000 proteins can be resolved from a single experiment.

stabilizing

How does acid/base catalysis help with speeding up a reaction? Acid-base catalysis facilitates a reaction by ____________________________ the charges in the transition state through the use of an acid or base, which donates protons or accepts them, respectively.

proton

How does acid/base catalysis help with speeding up a reaction? General acid-base catalysis involves a molecule besides water that acts as a ________________ donor or acceptor during the enzymatic reaction.

activated

How does acid/base catalysis help with speeding up a reaction? Nucleophilic and electrophilic groups are _________________________ as a result of the proton addition or removal and causes the reaction to proceed.

efficient

How does proximity/orientation catalysis speed up reactions? Over time, the "steering" has evolved and become more _____________________.

substrate

How does proximity/orientation catalysis speed up reactions? The proximity effect describes the orientation and movement of the _______________________ molecules when binding to enzyme active sites.

orbital

How does proximity/orientation catalysis speed up reactions? The________________ steering hypothesis states that just because a substrate and an enzyme active site are in close proximity does not mean that a catalysis reaction will occur.

occur

How does proximity/orientation catalysis speed up reactions? This is because the enzyme must guide or "steer" the substrate into the active site in a specific orientation in order for the reaction to actually ____________.

secondary, tertiary, coil, non

How does the addition of sodium dodecylsulfate (SDS) to proteins affect the basis of separation of the proteins via electrophoresis? (Select all that apply.) SDS disrupts the protein's _______________________ and _________________ structures. SDS treatment yields proteins with roughly the same shape, which is a random ________. SDS binds to proteins via ________-specific adsorption, giving a charge proportional to the protein mass.

low

How is dialysis used in protein purification? To remove ___________ molecular weight compounds such as salts.

equivalent

How is the KM related to substrate concentration when V = Vmax/2? KM is __________________ to the substrate concentration.

correlated

How might ELISA technology be used to assay for IgE or IgG-mediated food allergies? Please include: the premise for designing such a test; what the ELISA would contain and; what would be the goal of such testing. The premise behind this testing would be that high circulating levels of IgG antibodies would be _______________________ with food-allergy signs and symptoms. The ELISA test would involve plates coated with common food antigens. A patient's sera would then be added and serum rich in IgG antibodies would specifically bind to the food allergen. A second antibody that binds to IgG and contains the colorimetric assay would then be added. By rinsing after each addition, spectrophotometric analysis will determine which IgG is produced that binds with each specific food antigen. An ELISA allergy test could help physicians pinpoint allergies so that patients could avoid such foods and reduce allergy symptoms.

protein

How might a biochemist work to improve a specific harvest trait such as low nutrient content due to insufficient iron in a starch crop? Identify what _______________ players are involved in iron uptake and understanding how such enzymes catalyze the uptake and storage of iron is a necessary first step. To initially pull out such an enzyme, an enzyme assay needs to be developed. For example, if iron uptake requires iron reduction, an iron reduction assay needs to be developed. If the enzyme can also reduce other substrates, a colorimetric assay might be developed based on an alternative substrate for a rapid and low-cost enzyme assay. The enzyme could then be purified, isolated and biochemically characterized. Antibodies could be raised against the _______________ for subsequent immuno-localization of the enzyme in specific tissues. Later steps might be identifying how such an enzyme can be activated either transiently or constitutively. For example, can a gene from another plant that more effectively takes up iron be introduced into the starch crop? Or can an elicitor be added to the plant while growing to stimulate enzyme activity for iron assimilation?

turnover, divided, affinity

How to measure catalytic efficiency? ________________ number ___________________ by enzyme _____________ for substrate (Kcat/KM).

harsh, 15000

If you had a protein X, which is a soluble enzyme found inside the mitochocondrion, and you wished to separate it from a similar protein Y, which is an enzyme found embedded in the endoplasmic reticulum membrane, what two techniques from the following list would permit you to complete this separation? Indicate the first and second techniques in order of application to intact cells. first: ____________ homogenization of the cells second: centrifugation at _________________ x g

Polyacrylamide

In column chromatography or electrophoresis, which of the following gels would be most immune to contamination by bacteria and other organisms? __________________________, bc it is synthetic

transition

In the induced fit model when does the substrate bind most strongly to the enzyme? at the _____________________ state

interior, space

Larger proteins are excluded from most of the ________________ of the gel beads, so they have less available column _______________ to travel as compared to smaller proteins.

substrate

Local conditions can affect the specificity of an enzyme for its substrate, and thus the enzymes catalytic ability: which of the following alterations would most likely not affect an enzyme in this manner? Increased __________________ concentration

transferases

Moves a functional group; e.g. kinases

greater, higher, S, V

Noncompetitive inhibition is a limiting case in which the effect of binding inhibitor has no effect on the affinity for the substrate and vice versa. Suggest what a Lineweaver-Burk plot would look like for an inhibitor that had a reaction scheme similar to standard noncompetitive inhibition (shown at right), but where binding inhibitor lowered the affinity of EI for the substrate. The slope of the plot in the presence of the inhibitor will be _________________ than the slope in the absence of the inhibitor. The 1/V axis intercept of the plot in the presence of the inhibitor will be ___________________ than the intercept in the absence of inhibitor. Plots for separate experiments at different inhibitor concentrations will intersect where 1/[__] > 0 and 1/___ > 0.

stable, increase

Other things being equal, what is a potential disadvantage of an enzyme having a very high affinity for its substrate? (Select all that apply.) The enzyme-substrate complex will be in a deep energy well, meaning that the enzyme-substrate complex will be more ______________. High affinity of the enzyme for the substrate will _________________ the activation energy of the forward reaction.

Oxidoreductase

Oxidation-reduction reaction that involves NAD or FAD; e.g. glyceraldehyde-3-phosphate dehydrogenase

isomerase

Phosphoglucomutase, which catalyzes the formation of glucose-6-phosphate from glucose-1-phosphate, is best classified as which of the following enzyme type? _________________

N, C

Proteolytic enzymes digest polypeptides at specific locations as shown in the figure below. Based on biochemical convention, identify the C- and N-terminus of the intact polypeptide shown above. The biochemical convention is that polypeptides are written from the _____- to the _____-terminus going from left to right in a figure.

specificity

Proteolytic enzymes digest polypeptides at specific locations as shown in the figure below. Based on your knowledge of amino acid structure, predict what chemical feature of the polypeptide chain is trypsin recognizing that results in selective cutting after specific amino acid residues in the polypeptide chain? Cutting occurs after or on the C-side of large positively charged amino acids (e g. Lys and Arg) suggesting a ___________________ pocket in the trypsin enzyme that allows for protein-ligand interaction resulting in polypeptide digestion at specific locations.

feature

Proteolytic enzymes digest polypeptides at specific locations as shown in the figure below. Provide a rationale why trypsin might cleave polypeptides at one site and not another? The proteolytic enzyme trypsin recognizes some ________________ in the polypeptide R-group that causes the enzyme to favorably bind and cleave at defined sites.

changes

Provide examples of biochemical enquiries that could be addressed by 2-D gel electrophoresis. Protein _______________ in an agricultural crop with exposure to insect damage; protein _______________ in a tumor cell line with anticancer drug treatment; protein _______________ in cattle with _______________ in a feed supplement.

catalytic

Provide two examples where comparing ___________________ efficiency would be informative. Compare enzymatic activity for two lines of Cassava to determine if the more ancestral line has lower catalytic efficiency with respect to iron transport. Compare gene sequences with catalytic activity for sodium ion antiporter operative in plant vacuoles to identify potential gene mutations resulting in greater catalytic activity.

HIV, pregnancy

Provide two examples where human health can be monitored by ELISA detection. ___________, _____________________ via human chorionic gonadotropin detection

Ion, gel, affinity

Quantification of Protein Purification To test your ability to construct a purification table please fill in the blanks present in the above purification table. ________-exchange chromatography Total Activity 115,500 _________-filtration chromatography Yield 50% ________________ Chromatography Specific Activity 30,000

change, ranking

Quantification of Protein Purification What is the rationale for constructing a purification table when isolating a protein? Purification tables quantify the _________________ in specific activity of the target protein allowing for a _________________ of purification steps in terms of effectiveness.

Affinity, effective

Quantification of Protein Purification Which step exhibited the greatest loss of total protein? Is this step one that should be considered for removal from the purification protocol? ________________ Chromatography exhibited the greatest total protein loss but concomintanly with this overall protein loss, purification was increased almost 30 fold making it the most _________________ purification step.

Hydrophobic interaction Chromatography

Separation is by hydrophobic interactions between the resin and the protein; high solvent salts removes water from the protein environment allowing proteins to expose hydrophobic surfaces with less hydrophobic proteins eluting first from the column; solvent is high in salt.

salt fractionation

Separation is by protein precipitation with increasing salt concentrations; since this method is performed without column separation it is not a chromatography technique.

ion exchange

Separation is by resin charge (e.g. cation with carboxymethyl or anion with diethylaminoethyl) with proteins of a similar charge to the resin not binding to the column and eluting more rapidly; promoting elution is by increasing buffer pH or ionic strength.

gel filtration

Separation is by size with larger proteins having a shorter distance to travel as they are too large to enter resin pores in the column; elution is by simple buffer volume rinsing proteins from the column.

affinity chromatography

Separation is by unique attraction of proteins to the resin. For example, proteins with a hexahistidine tag will selectively and specifically bind to a nickel affinity column while all other proteins will rapidly pass through the column. A resin containing a specific ligand will retard protein movement by specific interactions (e.g. protein/antibody/receptor interaction with a ligand) while other polypeptides simply and rapidly pass through the column.

first

Sephadex G-75 has an exclusion limit of 80,000 molecular weight for globular proteins. If you tried to separate trypsinogen (MW 20,000) from β-amylase (MW 200,000) using this resin in a column, what would happen? β-Amylase would elute ___________, then trypsinogen would elute.

sequencing information

Sequencing of a characterized protein will confirm the presence of the integral polypeptide while sequencing of an unknown protein will provide novel primary sequence data.

contact

The active site is where the substrate makes ________________ with the enzyme.

active

The active site model (also called the lock and key model) of enzyme-substrate binding differs from the induced fit model in which of the following ways? The induced fit model holds that the shape of the ____________ site is altered during substrate binding

k

The active site of an enzyme E, which catalyzes a reaction X, is partially denatured: which of the following quantities associated with X is most likely to be affected by the partial denaturation of E compared to the native form of E? The rate-constant _____

largest

The first proteins to elute on a gel filtration column are the ______________________ proteins in the sample.

substrate

The induced fit model of enzyme binding states that which of the following molecules alters the enzyme active site to more closely match the shape of the substrate? the _______________

highest

The optimum temperature is the temperature at which enzyme activity is ________________.

slow

The rate at which this bond breaks is very ____________ when no enzyme is present.

exergonic, high, slowly

The reaction of glucose with oxygen to produce carbon dioxide and water, Glucose + 6O2 → 6CO2 + 6H2O has a ΔG° of -2880 kJ mol-1, making it a strongly exergonic reaction. However, a sample of glucose can be maintained indefinitely in an oxygen-containing atmosphere. How can these two facts be reconciled? Although the reaction is _____________________, the activation energy barrier for the reaction is so ___________ that the reaction occurs very ________________.

catalyzed

The substrate is the compound whose reaction is ______________________ by the enzyme.

decrease, centrifugation

The term "salting out" refers to a phenomenon whereby a highly soluble salt is added to a protein solution to ________________ the solubility of the protein. This change in protein solubility can be exploited by the use of _______________________ to concentrate and purify the protein.

pH, temperature, closer, enzyme, increase

This graph shows the rate of an enzyme-catalyzed reaction over time. Some change is made in the system at time A. Select all changes that could cause this increase in reaction rate. Changing the ________ or ______________________ so the conditions are _____________ to the optimal conditions for the enzyme and adding more _______________ will _________________ the rate at which the enzyme can process its substrate.

product, decreases

This graph shows the rate of an enzyme-catalyzed reaction over time. The temperature and pH are held constant. What could cause the rate to decrease? Check all that apply. As the substrate is converted to _________________, the concentration of substrate __________________ and the rate of the reaction __________________.

transition

To analyze the catalytic effect of two different enzymes on the same chemical reaction, it is best to compare which of the following quantities? The difference between ___________________ state energies

visualize, amount

What are the application differences between Coomassie blue or silver staining and a Bradford assay? Coomassie blue and silver staining is used to _________________ proteins in a gel while a Bradford assay binds to proteins in a solution and can determine the ________________ of protein present based on Beer's Law using a calibration curve.

Single, low, constant

What are the assumptions when using Michaelis-Menten enzyme kinetics? ______________ subunit and substrate Product at ______ level (V0) ES ______________ (steady state)

proteins

What can be said about the relationship between enzymes and proteins? Most enzymes are ______________.

products

What data analysis would be symptomatic that a protein has not been sufficiently purified for Edman sequencing analysis? Multiple _________________ for each reaction sequence.

enzyme concentration

What environmental factor(s) exhibit a direct, linear relationship with enzyme activity? ________________ _______________________

cooperative, efficiency, reversible

What information can be gleaned about an enzyme based on Michaelis-Menten kinetics? A substrate versus reaction velocity curve will identify if the enzyme exhibits _______________________ activity. Catalytic Efficiency (Kcat/KM) is a parameter that can be used to directly compare _________________ for different enzymatic systems. A Lineweaver-Burk plot can be used to identify whether _____________________ inhibitors are competitive, noncompetitive or uncompetitive.

mass, sequenced

What information can be gleaned from mass spectroscopy analysis? Peptides can be identified based on peptide ____________ fingerprinting or peptides can be ________________________ via tandem mass spectrometry.

half

What is KM as a quantity? Mathematically? The substrate concentration at which the reaction is at _________ maximal velocity KM = (k-1 + k2)/k1

negative, low

What is the difference between an enzyme catalyzed reaction that is thermodynamically and kinetically favorable? Thermodynamically favorable has a _____________________ ΔG while kinetically favorable has a _______ activation energy.

k, km, keq

What is the difference between k, KM and Keq? The rate constant for a reaction is ___; the aggregate of rate constants in Michaelis-Menten enzyme kinetics is _______; and the equilibrium constant for a reaction (a ratio of the product of the products over the product of the reactants) is _________.

activation energy

What is the name of the energy barrier that is required to cross to move from reactants to products? ______________________ ________________

increases, isoelectric

What is the relationship between protein solubility in an aqueous solution and the pH of the solution? Protein solubility ____________________ as the pH moves away from the protein ____________________ point as the molecule becomes more positively or negatively charged.

unreactive, common

What negative and/or positive controls would be advisable with such an ELISA testing? Include an ___________________ antigen as a negative control and a ______________ allergen (e.g. grass pollen, house dust mites or mold) as a positive control. Also divide samples to generate technical replicates of the assay.

breaking

What results with heating a polypeptide in the presence of acid? Non-specific _________________ of the peptide bonds.

Dextran, Polyacrylamide, agarose

Which of the following are used as resin material for column chromatography? ________________, ____________________________, ________________

H, pH, OH

Which of the following are valid reasons for carrying out enzymatic reactions in buffer solutions? (Select all that apply.) Some enzyme-catalyzed reactions consume ______+ ions. Enzyme activities are often strongly _______ dependent. Some enzyme-catalyzed reactions produce _______- ions.

hydrolase

Which of the following enzyme types catalyzes the formation of a single bond between two substrates through the elimination of water? ___________________

valine

Which of the following molecules cannot be classified as an enzymatic cofactor? _______________

size, net charge

Which of the following physical parameters of a protein control its migration in electrophoresis? __________, _______ _____________

open, supernatant

Which of the following scenarios is the best one to partially isolate a soluble cytosolic protein using only one differential centrifugation spin? Break __________ the cells and centrifuge at 100,000 × g. The protein will be in the _____________________.

mild, higher, low, high, not

Which of the following statements comparing enzymes and nonenzymatic catalysts are correct? (Select all that apply.) Enzymes are effective under _________ conditions, whereas nonenzymatic catalysts require ______________ temperatures and pressures. Nonenzymatic catalysts are _______ molecular weight compounds, whereas enzymes are _________ molecular weight proteins. All enzymes are catalysts, but ________ all catalysts are enzymes.

ATCase, allosteric

Which of the following systems do not follow Michaelis-Menten kinetics? (Select all that apply.) The enzyme _______________. An __________________ enzyme with [S] > KM.

positively

While proteins can have an overall positive or negative charge at a given pH, why do all proteins migrate from the cathode (-) to the anode (+), in an SDS-PAGE separation? All proteins are first coated with sodium dodecyl sulfate (SDS) making the outer surface of each polypeptide ____________________ charged.

carbon dioxide gas

Why do sodas fizz more when you drink them? Soda is fizzy because the gas _________________ __________________________ is dissolved into the sweet, syrupy liquid. _________________ __________________________ molecules have a natural tendency to leave any liquid, popping through the surface and escaping forever as a __________.

cleaves, signals

Why does protein sequencing by Edman degradation required a purified protein? Each round of chemical reactions ______________ off the N-terminus of the polypeptide; if there are multiple types of polypeptides then there will be multiple ________________ making it impossible to interpret N-terminus data.

variable

Why is ELISA testing not utilized for monitoring viral-caused influenza? To develop an antibody that is specific and unique for the virus takes many months and an ELISA assay requires such an antibody; the highly _______________ nature of seasonal viral flu strains would require the generation of new antibodies each year; moreover, identifying viral flu would not significantly aid in treatment since there are few effective antiviral treatments available.

heterogeneous

Why is there a limit in the number of cycles that can be interpreted by Edman degradation? Because each reaction cycle is less than 100% efficient so after many reaction-cycles the N-terminus for the pool of polypeptides becomes _________________________ in length.

inhibitor

With no ________________ present, the reaction acts as a simple enzymatic, two-step catalysis reaction.

Trypsin, basic

________________ cuts peptides after ____________ residues (Lys and Arg).

heating

_________________ a protein solution will denature the proteins.

Cyanogen bromide, Met

__________________ _______________ cuts peptides after _________ residues.

Chymotrypsin, aromatic

_______________________ cuts peptides after _______________ (Phe, Tyr, and Trp) residues.

High, large, decreasing

how does salting out work? ___________ levels of salt interact with a _____________ portion of the water dipoles, thus __________________ the number of interactions of the protein with water.