Biochemistry Chapter 5, 6, and 7

Protein ____will be more stable when folded. This is best explained because its disulfide bond provides a greater degree of conformational constraints on the ____form as compared to the disulfide bond in protein ____. This means the unfolded form of protein ____ will be less stable than that of protein ____, leading to a greater stability when folded.

#1, unfolded, #2, #1, #2

At pH=7 a DNA-binding protein is expected to carry an excess (+) charge that will lead to favorable binding to the (−−) charge on the DNA molecule (e.g., histones are highly positively charged). A positively-charged protein will bind to a column carrying an excess (−−) charge. Thus, at pH=7, CM-cellulose is expected to bind to a DNA-binding protein.

+ - positively positively - CM

The (++) charge on amines is neutralized by acetylation; thus, there is a(n) decrease in charge when a protein is treated with acetic anhydride. At pH=7 the thiol of cysteine is mostly protonated (uncharged); thus, addition of negatively-charged carboxymethyl groups will result in increased (−−) charge density. Phosphorylation at pH=7 will increase (−−) charge density since hydroxyl groups are uncharged at physiological pH.

+ decreased uncharged - - uncharged

A short 8-residue sequence of a polypeptide is determined to have φ angles ranging from -65 degrees to -80 degrees and ψ angles ranging from -40 degrees to -50 degrees. What conclusion can be drawn from this data? - The sequence has no defined secondary structure. - No conclusion can be drawn. - This segment is mostly β strands. - This segment has helical content.

- This segment has helical content.

Which of the following characteristics are true about a typical peptide (amide) bond? - The bond is planar. - There is free rotation about the carbonyl carbon and nitrogen bond. - There is substantial double-bond character to this bond. - There is a net negative charge on nitrogen and net positive charge on oxygen.

1 and 3

Which statement(s) is/are true about amyloid fibrils? 1. Amyloid fibrils are characterized by highly organized arrays of β sheet structure. 2. Amyloidogenic proteins are associated with human disease states like Alzheimer's disease, Parkinson's disease, Cataracts 3. Fibrils are formed from a left-handed helix of four "protofibrils". 4. Amyloid disease is not correlated with inherited genetic mutations.

1, 2, and 3

Aromatic amino acids absorb light in the near-ultraviolet region of the electromagnetic spectrum. Which of the following statements about absorption of proteins are true? - The absorption of light at 280 nm is often used for the detection and/or quantification of proteins. - Phenylalanine does not absorb at 280 nm, and it absorbs only weakly at 258 nm. - Amino acids absorb as strongly as nucleic acids - Tryptophan and tyrosine account for most of the UV absorbance by proteins in the region around 280 nm.

1, 2, and 4

Which of the following statement(s) about amino acids is/are true? - Arginine has a guanidinyl group. - The side chain of histidine has a pKa value of 6.0. - Histidine forms a covalent bond with the α-amino group. - The side chain of cysteine has a pKa of 8.3.

1, 2, and 4

Which statements about the "energy landscape" model of protein folding are true? 1. The depth of the funnel corresponds to free energy, and the width of the funnel corresponds to the number of conformational states at a given value of free energy. 2. This model averts Levinthal's paradox. 3. The classical pathway model and the folding funnel are not compatible. 4. The trajectory of protein folding is "downhill". It proceeds with a decrease in free energy.

1, 2, and 4

The stability of the folded structure of a globular protein depends on the interplay of which of these factors: 1. ΔH generally favors the folded state and is associated with changes in noncovalent bonding interactions. 2. ΔH of the surrounding medium, which generally favors the folded state of the protein. 3. ΔSconformation of the protein favors the unfolded state. 4. ΔSsolvent is favorable due to the release of water from clathrates. This occurs when solvent exposed hydrophobic groups become buried within the molecule.

1, 3, and 4

Which statement(s) about collagen is/are true? 1. Collagen is the most abundant single protein in most vertebrates. 2. Tropocollagen is a double helix of two polypeptide chains. 3. Tropocollagen is the basic unit of a collagen fiber. 4. The individual chains are left-handed helices, with ∼3.3 residues/turn.

1, 3, and 4

Which statements about the primary structure of a specific protein are true? - The primary structure is a unique and defined amino acid sequence. - The primary structure is different from one organism to the next organism of the same species. - The primary structure determines the secondary and tertiary structure. - The amino acids are connected through peptide bonds.

1, 3, and 4

Match the codon with the amino acid it encodes: 1) UCA A) Stop 2) CUA B) Lys 3) AAG C) Start/Met 4) GUA D) Leu 5) AUG E) Val 6) UAG F) Ser

1:F; 2:D; 3:B; 4:E; 5:C; 6:A

Which of the following are characteristics of a living system? 1. the ability to resist change over generations of progeny 2. the ability to couple energy-releasing reactions with energy-requiring processes, thereby allowing 3. the creation of complex molecules 4. the ability to replicate and regenerate the ability to respond to changes in the environment

2, 3, 4 are correct.

Which of the following proteins assist/help in protein folding? 1. Proteasome 2. Protein disulfide isomerase 3. Prolyl isomerase 4. Molecular chaperones like GroEL-GroES complex

2, 3, and 4

Which statements about the binding of oxygen to heme are true? 1. The iron ion bound to the porphyrin group is +3. 2. In deoxyhemoglobin, the porphyrin nitrogens make up four of its six ligands, the nitrogen of His F8 makes up the fifth ligand, and the last remaining coordination site is empty. 3. When O2 is bound to the iron cation, His E7 makes a key H-bonding interaction with this ligand. 4. Heme is capable of binding other ligands, such as CO and NO, but it is the key interactions of oxygen with protein side chain residues that enhance the specificity for oxygen.

2, 3, and 4

Which of the statements fit the description of α helices best. - large dipole moment, parallel or antiparallel orientation, extensive hydrogen bonding pattern - 5.4Å/turn, extensive hydrogen bonding network, large dipole moment - extensive hydrogen bonding network, large dipole moment - 5.4Å/turn, extensive hydrogen bonding network

5.4Å/turn, extensive hydrogen bonding network, large dipole moment

From the 6 codons for Arg, 2 can be converted to HisHis codons by single-nucleotide changes, whereas 4Arg codons can be converted to SerSer codons by single-nucleotide changes. The Arg-to-Ser mutation is more probable.

6 2 4 Arg-to-Ser

When incorporated into a protein, the side chain of histidine has a typical pKa value in the range of 6.5-7.4. The pKa value is dependent on the electrostatic environment surrounding the histidine residue. However, when analyzing the pKa values in a particular protein, scientists determined that one particular His residue has an unusually low pKa value of 4.8. Which answer is a possible explanation for this observation? - A negatively charged amino acid could be in close proximity to this residue. - A positively charged amino acid could be in close proximity to this residue. - This residue must be located on the surface of the protein. - The residue has been chemically modified.

A positively charged amino acid could be in close proximity to this residue.

Which of the following statements characterize an α helix (A) or antiparallel β strand (B)? 1. The rise per residue is 1.5 Å. 2. The side chains are located on opposite faces of the secondary structure element. 3. There are 2 residues per turn. 4. 9The pitch is 5.4 Å.

A- 1,4; B-2,3

Which of the following statements about protein quaternary structure are correct? 1. It involves a complex of two or more proteins interacting with each other. 2. The subunits of the structure can be either identical or different. 3. The interactions between subunits can give rise to indefinite growth of polymeric complexes. 4. Most assemblies of protein subunits have one or more defined axis of rotation.

All of the listed statements are correct

Which of the following statements regarding the folding of proteins are true? 1. The burying of hydrophobic groups within a folded protein molecule away from water leads to a stabilizing entropy increase known as the hydrophobic effect. 2. Internal hydrogen bonds stabilize the fold. 3. Salt bridges stabilize the fold. 4. Van der Waals interactions have a stabilizing, cumulative effect.

All statements are correct

Which statement(s) about the peptide bond is/are true? - The peptide bond has a substantial fraction of double-bond character. - Two α-carbon atoms on either side of a peptide bond can be in either cis or trans configurations. - The peptide bond is metastable (meaning that it will hydrolyze in an aqueous solution when a catalyst is present). - Peptide bonds hydrolyze in aqueous solution in the presence of proteases, strong mineral acids or cyanogen bromide.

All statements are true

Which statement correctly describes amphipathic (or amphiphilic) helices and sheets? - Sheets are typically hydrophilic on one surface, whereas helices usually have both hydrophilic and hydrophobic residues evenly distributed throughout their structure. - Amphipathic helices and sheets have predominantly hydrophilic residues on one face and predominantly hydrophobic residues on an opposite face. - Amphipathic helices and sheets have hydrophilic and hydrophobic residues evenly distributed throughout their structure. - Helices are typically hydrophilic on one surface, whereas sheets usually have both hydrophilic and hydrophobic residues evenly distributed throughout their structure.

Amphipathic helices and sheets have predominantly hydrophilic residues on one face and predominantly hydrophobic residues on an opposite face.

Phospholipids provide the foundation for biological membranes. They are considered amphipathic. What does this property mean?

Amphipathic means that the molecule is both hydrophobic ("water-fearing") and hydrophilic ("water-loving").

Do you think apamine is synthesized in the form CNCKAPETALCARRCQQHCNCKAPETALCARRCQQH, or is it more likely a product of proteolytic cleavage of a larger peptide? Explain. - When apamine is released from a ribosome following translation, its synthesis is finished. - Synthesis of apamine involves proteolytic cleavage of its dimer. - Apamine does not have an NN-terminal methionine, so at least some proteolytic cleavage must be involved in its synthesis.

Apamine does not have an NN-terminal methionine, so at least some proteolytic cleavage must be involved in its synthesis.

Which of the following statement is true about a protein in aqueous solution that has a pH equal to the isoelectric point (pI) of the protein? - There is not enough information to answer this question. - At pH = pI, there is a net negative charge on the protein. - At pH = pI, there is no net charge on the protein. - At pH = pI, there is a net positive charge on the protein.

At pH = pI, there is no net charge on the protein.

At PO2 = 40 mm Hg, which statement about the saturation of either myoglobin (Mb) or hemoglobin (Hb) is true? - At this partial pressure of oxygen, Mb would be almost completely saturated but Hb would not. - At this partial pressure of oxygen, both Hb and Mb would be equally saturated with oxygen. - At this partial pressure of oxygen, Hb would be completely saturated but Mb would not. - At this partial pressure of oxygen, neither Hb nor Mb would be fully saturated with oxygen.

At this partial pressure of oxygen, Mb would be almost completely saturated but Hb would not.

A protein is found to be a tetramer of identical subunits. Name two symmetries possible for such a molecule. What kinds of interactions (isologous or heterologous) would stabilize each? C4 symmetry with heterologous interactions D2 symmetry with isologous interactions D4 symmetry with heterologous interactions C4 symmetry with isologous interactions C2 symmetry with isologous interactions D2 symmetry with heterologous interactions

C4 symmetry with heterologous interactions D2 symmetry with isologous interactions

Which biochemical technique is used to determine the approximate content of α-helix, β-strand, and random coil in a protein. This method is not considered high resolution. - Circular dichroism (CD) - Fluorescence spectroscopy - X-ray crystallography - Absorption spectroscopy

Circlular dichroism (CD)

Acetylating agents such as acetic anhydride react preferentially with primary amines, iodoacetate reacts preferentially with sulfhydryl groups, and ATP-dependent kinases preferentially add a phosphoryl group to side-chain hydroxyl or phenolic −OH groups. Which amino acid side chains, or main chain groups, in a polypeptide are most likely to be modified by treatment with: Iodoactate Check all that apply: Cysteine Methionine Valine Serine

Cysteine

The formation of insulin from preproinsulin follows 4 steps. Organize them into the correct order. A) Disulfide bonds form B) The connecting sequence is cleaved to form the mature insulin molecule C) After membrane transport, the leader sequence is cleaved and the resulting proinsulin folds into a stable conformation D) Preproinsulin is synthesized as a random coil on membrane-associated ribosomes

D-C-A-B

Suppose a tetramer, like streptavidin, consists of four identical subunits. What is the highest symmetry now possible? D2 C1 D4 C3 C2

D2

Part complete The phosphofructokinase tetramer displays which symmetry?

D2 symmetry

What qualitative effect would you expect each of the following to have on the P50P50 of hemoglobin? Decrease in PCO2 from 40 to 20 mm Hg

Decrease in P50

What qualitative effect would you expect each of the following to have on the P50P50 of hemoglobin? Dissociation into monomer polypeptide chains

Decrease in P50

Ferrous iron (Fe2+) is octahedrally coordinated. This means it should have six ligands. Which are the coordination sites in hemoglobin? - Five coordination sites are coming from the ε-nitrogens of histidine residues from helices C-F. The sixth coordination site is the binding site for oxygen. - Four ligands are provided by the nitrogen atoms of the porphyrin ring. The fifth ligand is the ε-nitrogen from histidine residue 93. The sixth coordination site is the binding site for oxygen. - Four ligands are provided by the nitrogen atoms of the porphyrin ring. The fifth and sixth coordination site is the binding site for oxygen. - Three ligands are provided by the nitrogen atoms of the porphyrin ring. The fourth and fifth ligands are coming from two histidine residues via their ε-nitrogens. The sixth coordination site is the binding site for oxygen.

Four ligands are provided by the nitrogen atoms of the porphyrin ring. The fifth ligand is the ε-nitrogen from histidine residue 93. The sixth coordination site is the binding site for oxygen.

Knowing the chemical properties and bulkiness (molecular weight) of amino acids indicates often the functionality of amino acids in protein structure. Sort glycine, tryptophan, phenylalanine, cysteine, and lysine by their molecular weight. Sort from lowest to highest molecular weight. - Glycine - lysine - cysteine - phenylalanine - tryptophan - Glycine - cysteine - lysine - phenylalanine - tryptophan - Cysteine - glycine - lysine - phenylalanine - tryptophan - Glycine - cysteine - lysine - tryptophan - phenylalanine

Glycine - cysteine - lysine - phenylalanine - tryptophan

Glycine, alanine, valine, leucine, isoleucine, and proline are considered amino acids with nonpolar aliphatic side chains. Which of these amino acids are often observed on the surface of protein? Glycine and proline Leucine and isoleucine Glycine and leucine Proline and isoleucine

Glycine and proline

CO2 and 2,3-BPG effect the ability of hemoglobin to bind oxygen. Which statement is true? - Stripped Hb cannot bind CO2 or 2,3-BPG. - If stripped Hb is treated with 2,3-BPG, the O2-binding curve for Hb will shift left. - If stripped Hb is treated with CO2, the O2-binding curve for Hb will match the binding curve for Hb with 2,3-BPG. - If stripped Hb is treated with 2,3-BPG and CO2, the O2-binding curve for Hb will mirror that of fully intact Hb.

If stripped Hb is treated with 2,3-BPG and CO2, the O2-binding curve for Hb will mirror that of fully intact Hb.

In the experiments of Barrick et al. (see the figure below), it was observed that replacement of histidine by a noncovalently bonded imidazole not only reduced cooperativity but also increased the oxygen affinity of the hemoglobin. The effect of replacing the proximal histidine in hemoglobin with a glycine residue and adding a noncovalently bonded imidazole. Suggest an explanation.

In native Hb, the binding of oxygen is actually hindered by the fact that pulling on helix F must move it against constraints within the molecule. In the imidazole replacement, there is no need to do the extra work of moving helix F. This difference shows up as a more favorable free energy for binding.

Insulin is a peptide therapeutic used to manage Type 1 diabetes, which affects more than 20 million people worldwide according to the International Diabetes Federation. A significant limitation to the broad distribution and use of insulin to treat Type 1 diabetes is the fact that it must be administered by injection rather than orally. Why is insulin administered by injection and not orally? - Insulin would not survive transit through the stomach and gut environments. - Insulin would be broken down in the mouth. - Insulin cannot be made in a solid form (pills).

Insulin would not survive transit through the stomach and gut environments.

Cytochrome c, an essential protein of the electron transport chain, is located in the mitochondria. Please identify its specific location. Matrix Inner membrane Outer membrane Intermembrane space

Intermembrane space

Suppose you had separated the A and B chains of insulin by disulfide oxidation. What chromatographic method should make it possible to isolate pure A and B chains?

Ion exchange chromatography. The A chain contains no basic residues in comparison with the B chain, so ion-exchange chromatography should work well

Each residue in a polypeptide chain has two backbone bonds: Blank, about which rotation is permitted. The angle of rotation about the Blank bond is referred to as ϕ (phi) and that about the Blank bond is called ψ (psi). These angles describe the Blank conformation of any particular residue in any protein, and allow one to predict whether a combination of amino acids in a polypeptide will be able to form and maintain Blank. Proline is not able to Blank the ideal ϕ and ψ angles for an αα helix, owing to the presence of the rigid imidic group as its side chain. Furthermore, proline does not have an Blank that acts as a stabilizing Blank in the middle of the helix. As a consequence, the secondary structure is predicted to be Blank.

N-Ca-C, N-Ca, Ca-C, backbone, a stable secondary structure, adopt, a-NH group, H-bond donor, destabilized

Acetylating agents such as acetic anhydride react preferentially with primary amines, iodoacetate reacts preferentially with sulfhydryl groups, and ATP-dependent kinases preferentially add a phosphoryl group to side-chain hydroxyl or phenolic −OH groups. Which amino acid side chains, or main chain groups, in a polypeptide are most likely to be modified by treatment with: Acetic anhydride Check all that apply: Arginine Glutamine Proline Aspargine N-terminal amine

N-terminal amine

Eukaryotic genes are discontinuous, containing regulatory, protein-coding sequences (exons) and intervening sequences (introns). The primary transcript pre-mRNA is cut and spliced. In which part of the cell does this occur? rough endoplasmic reticulum cytoplasm nucleus mitochondria

Nucleus

As the crocodile stays underwater, its hemoglobin delivers most of the bound _____as a result of _____ binding of ____ to the ____ conformation.

O2, increased, HCO3-, T

APFLLIGDWY is chain of amino acids, which can also be referred to as a(n)... Tetrapeptide Protein Oligopeptide polypeptide

Oligopeptide

Which of the following statements about the Bohr effect are true? 1. This is the effect of pH on the binding of O2 to Hb. 2. As blood travels from lung to tissue, there is a drop in pH, causing Hb to unload more oxygen than if there were no change in pH. 3. As blood travels from lung to tissue, there is an increase in pH, causing Hb to unload more oxygen than if there were no change in pH. 4. Myoglobin and Hb exhibit similar pH profiles.

Only statements 1 and 2 are correct

Hemoglobin (Hb) can be viewed as having two quaternary states, a low oxygen affinity state (T), and a high oxygen affinity state (R). Which of the following statements about the binding of O2 by Hb are true? 1. Upon binding a molecule of oxygen, Hb undergoes a conformational change that makes the binding of subsequent O2 molecules more favored. 2. The conformational change induced in Hb upon binding oxygen is the result of a small movement (0.2 Å) of the iron cation into the center of heme. 3. Site-directed mutagenesis studies have indicated that the cooperativity of O2 binding in Hb is attributable to the movement of the F helix in Hb. 4. Site-directed mutagenesis studies in which the proximal His residues of the F helix have been replaced by glycines have indicated the mutant protein still shows cooperativity of O2 binding.

Only statements 1, 2, and 3 are true

Which of the following statements regarding Anfinsen's denaturing experiments with ribonuclease A (RNAse A) are valid? 1. Exposing the denatured protein to air oxidation and then dialysis to remove urea restored the protein to its original functionality. 2. Removing urea by dialysis and then allowing air oxidation of the denatured protein restored the protein to its original functionality. 3. Denaturing the protein with both urea and β-mercaptoethanol yielded an inactive protein. 4. Anfinsen concluded that protein folding is determined by its primary sequence.

Only statements 2, 3, and 4 are valid

Many of the D-amino acids found in nature have been discovered in bacterially produced peptides that have antibiotic properties. Bacteria secrete these peptides into their environments to kill competitor bacteria and thereby gain a selective advantage. Given your answer to part (a) of this question, what potential advantages might D-amino acids confer to a secreted peptide toxin? Peptides containing D-amino acids are less likely to be recognized as substrates by proteolytic enzymes in the gut. Peptides containing D-amino acids are more likely to be recognized as substrates by dehydratase enzymes in the gut.

Peptides containing D-amino acids are less likely to be recognized as substrates by proteolytic enzymes in the gut.

Which of the following secondary structure element is left-handed? - 310 helix - α helix - B-form DNA - Polypeptide II helix

Polypeptide II helix

Proteins structure is broken down into separate levels of organization. The secondary structure of a protein is best described by which statement? - The secondary structure of a protein is the amino acid sequence. - Secondary structure of a protein is the adoption of a locally repeating structure. - The secondary structure of a protein is the assembly of local structure elements that associate along their hydrophobic surfaces to give a stably folded structure - The secondary structure of a protein arises when two or more polypeptide chains folded into tertiary structures interact to form well-defined multisubunit complexes.

Secondary structure of a protein is the adoption of a locally repeating structure.

Human and sperm whale myoglobin have very similar primary structures. Which of the following statements are correct? - The two proteins are very likely related evolutionarily. - The differences in the sequences in many instances represent a conservative change (such as L for I). - The differences in the sequences in many instances represent a nonconservative change (such as D for A). - There is no correlation between the two proteins, since they originate from very different species.

Statements 1 and 2 are correct

Which statements about β turns are correct? 1. Their purpose is to reverse the direction of the polypeptide chain. 2. There are two types, I and II, which differ mainly in the conformation about the i+1 and i+2 residue amide bond. 3. They typically contain large, hydrophobic residues. 4. Their conformation is held in place through H bonds.

Statements 1, 2, and 4 are correct

Acetylating agents such as acetic anhydride react preferentially with primary amines, iodoacetate reacts preferentially with sulfhydryl groups, and ATP-dependent kinases preferentially add a phosphoryl group to side-chain hydroxyl or phenolic −OH groups. Which amino acid side chains, or main chain groups, in a polypeptide are most likely to be modified by treatment with: Kinase + ATP Check all that apply: Aspartic Acid Glutamic Acid Tyrosine

Tyrosine

Which of the following codons serves as stop signal? CUU UAG GGU AUG

UAG

The hydrophobic residues in this sequence tend to recur roughly every 3-4 amino acids, suggesting that the protein sequence shown is in the form of an ______ comprising _______ residues. Such a sequence would result in a ______ structure which has opposing ______ faces. Thus, this sequence is that of an amphipathic (or amphiphilic) _______.

a helix, hydrophobic and hydrophilic, secondary, hydrophobic and hydrophilic, a helix

A protein stripped of its cofactor or metal ion is best described as? - holoprotein - cofactor - apoprotein - prosthetic group

apoprotein

Peptides typically carry (--) that reduce transport across the (--) core of the membrane bilayer.

charged groups (i.e., N- or C-termini and some side chains) hydrophobic

The basic secondary structure of which of these fibrous proteins is a β-sheet structure. - collagen - All above proteins are β-sheets - fibroin - α-keratin

fibroin

What qualitative effect would you expect each of the following to have on the P50P50 of hemoglobin? Decrease in pH from 7.3 to 7.1

increase in P50

What qualitative effect would you expect each of the following to have on the P50P50 of hemoglobin? Increase in 2,3-BPG concentration from 4 mM to 6 mM in red cells

increase in P50

The formation of favorable ___________ ionic or ________ interactions in a _____ protein replace interactions between solvent (water) and the ionic species (or _____ donors and acceptors) in the _______ state. The favorable ΔH obtained by formation of ______ bonds in the ______ protein is offset by the energy required to _____ many interactions with solvent going from the ______ to the _______ state.

intramolecular, H-bonding, folded, H-bond, unfolded, intramolecular, folded, break, unfolded, folded

Chaperones are meant to prevent _______, which is mediated by the intermolecular association of ______ surfaces. ________ protein will minimize solvent-exposed _______ surface area. Thus, as proteins unfold, more ______ surface area will be exposed, triggering ______ by chaperones.

irreversible aggregation of unfolded proteins, hydrophobic, a folded, hydrophobic, hydrophobic, recognition

Assuming a membrane potential across the inner membrane of 176 mVmV (inside negative), calculate the ratio of the [Ca2+][Ca2+] in the matrix to that in the cytoplasm ([Ca2+]m/[Ca2+]c)([Ca2+]m/[Ca2+]c) that would exist at equilibrium (i.e., ΔG=0ΔG=0).

lecture 10, part III

The resonance structure on the _____ is the preferred resonance structure because it _____

left, minimizes formal charge

What is the net charge on the following peptide at pH = 0?Peptide sequence: DSVK net charge = -2 net charge = +1 net charge = +2 net charge = 0

net charge = +2

Interactions of ________ side chains in the protein sequence lead to the formation of a tightly packed _______ core. This core is stabilized by a ______ number of _________. When a mutation occurs, it destabilizes the protein core and weakens ________ leading to misfolding.

nonpolar, hydrophobic, large, van der Waals contacts, van der Waals contacts

It is ______ to result in increase O2 delivery to muscles because a drop in CO2 will _____ the stability of the T state, which results in a _____ P50 and ____ O2 release from hemoglobin.

not likely, reduce, reduced, less

If so, is the pI of the modified peptide higher or lower than that of the untreated peptide?

pI is lower in every case

Modification of the N- and C-termini (by, respectively, acetylation and amidation) will (--) the charge density on peptides. This would make them (--) likely to cross membranes.

reduce more

In a peptide bond, the length of the C−N bond is ______than the average C−N bond as shown in the table. When looking at the image showing bond lengths and angles for a peptide bond, the angles around both the _____ atom and the _____atom are approximately ____, which indicates that both atoms are ____ hybridized and also in the same plane. Both the bond length and the planar structure suggest that the resonance structure where there is a _____ bond between the _____ and _____ plays a significant, although minor, role in the overall structure of the peptide bond.

shorter, carbonyl carbon, nitrogen, 120 degrees, sp2, double, carbonyl carbon, nitrogen

Which of the following statements about globular proteins are true? 1. The protein folds to make itself as compact as possible. 2. The packing of the protein is such that hydrophilic residues appear on the surface where they can interact with an aqueous environment. 3. β sheets are usually twisted, or wrapped into barrel structures. 4. All parts of a globular protein can be classified as helix, β sheet, or turns.

statements 1, 2, and 3 are correct

The curve will exhibit inflections corresponding to (--) group(s) titrating near 4 (--), (--) group(s) near 6.5 (--), (--) group(s) near 8 (--), (--) group(s) near 10 (--), and (--) group(s) near 12 (--).

two carboxyl terminus and glutamic side chain histidine one N-terminus two lysine and tyrosine one arginine