BIOCHEM QUIZ 2

what happens to enzymes when body temperature rises

-98.6 F/37C enzyme at height of activity heat rises= rise in activity - colder temp = decrease in enzyme activity

competitive enzyme inhibitor

-a molecule that sufficiently resembles an enzyme substrate in shape and charge distribution that it can compete with the substrate for occupancy of the enzyme's active site -directly competes with binding of substrate to active site

given the following decapeptide sequence, which amino acids would you expect to be on the surface of this molecule once it folds into its native conformation? asp-ser-gly-ala-ala-tyr-leu-cys-met

-hydrophilic amino acids (polar,basic, acidic) - asp, ser

a mutational change alters a polypeptide by substituting three adjacent prolines for three glycine. what possible effect will this even have on the proteins structure?

-proline (3 carbon side chain ring), changes the structure of the polypeptide and therefore changes its function

general base catalysis

A mechanism of catalysis, in which a group that is weakly ionized accepts a hydrogen ion from the substrate, and/or polarizes groups of the substrate.

Ligase

An enzyme that connects two fragments of DNA to make a single fragment Joining of molecules; uses ATP

covalent catalysis

Enzyme forms a covalent bond with the substrate

quarternary structure of a protein

Overall protein structure, combining 2 or more polypeptides How individual polypeptides come together to make a complex protein.

tertiary structure of protein

Protein structure is formed when the twists and folds of the secondary structure fold again to from a larger 3D structure Defined by the hydrophilic and hydrophobic interactions between R groups of amino acid chains.

disulfide bonds

Strong chemical side bonds formed when the sulfur atoms in two adjacent protein chains are joined together.

how is the activation energy related to the reaction rate (directly or inversely)

They are inversely related because as one goes up the other goes down (increase in activation energy = decrease in reaction rate and vice versa)

Zwitterion

a molecule or ion having separate positively and negatively charged groups.

Lyases

add groups to or remove groups from double-bonded substrates

for the pentapeptide ala-tyr-gly-ser-val, draw the products of its complete chymotrypsin proteolysis

ala-tyr, gly-ser-val

a small molecule that decreases the activity of an enzyme by binding to a site other than the catalytic site is termed a(n)

allosteric inhibitor

uncompetitive inhibitor

binds to the enzyme-substrate complex, preventing release of products

Oxidoreductases

catalyze oxidation-reduction reactions

hydrocarbon chain

chain of carbon atoms bonded to each other and to hydrogen atoms

Chymotrypsin

digestive enzyme, splits where aromatic ring is when doing proteolysis

cystine is unique among the amino acid which is formed by the reaction of two cysteines because it contains a ___________ bond

disulfide

which of the following acids is most soluble in water at pH 7.0? glutamate leucine tyrosine phenylalanine

glutamate

Hydrolase

hydrolysis (addition of water)

When a metal ion such as Pb(II) interferes with the functioning of an enzyme, the most probable mechanism is

irreversible inhibition

Enzymes function as catalysts by

lowering the value of the activation energy

secondary structure of protein

protein structure is formed by folding and twisting of amino acid chain alpha and beta helix sheet

amino acid polymers consisting of more than 50 amino acids are called

proteins

Isomerase

rearranges bonds within a molecule to form an isomer

which is a property of protein tertiary structure

tertiary structures usually contain hydroxyl R-groups on the exterior of the protein where they can favorably interact with water.

primary structure of protein

the amino acid sequence of the polypeptide chain

Proteolysis

the breakdown of proteins or peptides into amino acids by the action of enzymes

two proteins, myoglobin and hemoglobin, are compared. which characteristics are shared by these two proteins

they both are globular proteins containing the common amino acids, porphyrin, and iron

transferase

transfers a functional group

Overdosing on vitamins A and D is more likely than overdosing on vitamin C because

vitamins A and D are fat soluble and thus can accumulate in body fat, where vitamin C is water soluble and the excess will be excreted in urine