Lecture 11 - Enzymes I

Question 1

The most common of all enzymatic reactions.

Answer 1

Redox (oxidation-reduction) reactions.

Question 2

Primary f(x)s of enzymes

Answer 2

Lower activation energy (Ea) and stabilize the transition state)

Question 3

How does one increase the production of products (according to Le Chatlier’s Principle)?

Answer 3

Decrease [product] or increase [reactants]

Question 4

What is meant by “coupled reactions” in terms of biochemical reactions?

Answer 4

The energies of a set of reactions are additive. In other words, if A-> B has a (+) G, and B->D has a (-) G, they can be added together. If the sum of both G’s is (-), the reaction is OVERALL spontaneous.

Question 5

G*’

Answer 5

-RTln([prod]/[react])

Question 6

These reactions revolve around the transfer of electrons.

Answer 6

Oxidation-reduction reactions

Question 7

Gain of an e-

Answer 7

Reduction

Question 8

loss of e-

Answer 8

Oxidation

Question 9

Gain of H+

Answer 9

Conjugate acid

Question 10

Loss of H+

Answer 10

Acid

Question 11

What portion of an enzyme determines specificity for a substrate?

Answer 11

Active site

Question 12

Cleavage of peptide bonds

Answer 12

Protelytic reactions

Question 13

What is the Vmax?

Answer 13

The maximum rate (reaction velocity) at which a reaction can occur.

Question 14

What produces a maximum velocity (Vmax) in reactions?

Answer 14

The complete saturation of the active site on an enzyme.

Question 15

3-D region or crevice that is produced after the residues from various parts of a protein come together in the 3* structure

Answer 15

active site

Question 16

Highly unstable intermediate in enzymatic reactions

Answer 16

transition state

Question 17

What is the “purpose” of an enzyme (specifically, HOW does an enzyme catalyze reactions)?

Answer 17

by lowering the activation energy of a given reaction

Question 18

Why are many vitamin deficiencies the cause of enzymatically driven health problems?

Answer 18

Often, vitamins serve as co-factors for enzymes. W/o the co-factor, the enzyme is an “apoenzyme,” devoid of function.

Question 19

An enzyme that contains its co-factor and is biologically active

Answer 19

holoenzyme (“holo-“ = “complete”)

Question 20

Two f(x)s of metals as co-factors

Answer 20

Stabilize A.S. and donate e- to the chemical reaction

Question 21

small organic molecules used as a co-factor

Answer 21

co-enzymes

Question 22

An enzyme w/o its necessary co-factor

Answer 22

apoenzyme

Question 23

Tightly bound co-enzymes are known also as _____.

Answer 23

prosthetic groups

Question 24

Pathophysiology of scurvy

Answer 24

A lack of co-factor (Vit. C) for prolyl hydroxylase, prevents addition of -OH in collage

Question 25

Pathophysiology of ariboflavinosis

Answer 25

A lack of riboflavin (Vit. B2) prevents activation of FAD; this causes decreased glutathione reductase function, and results in UV light damage to areas exposed to the sun through production of free radicals (no FAD to “snag” high energy free radicals)

Question 26

enzyme that transfers e- between compounds

Answer 26

oxidorecutase

Question 27

enzyme that moves f(x) group between compounds

Answer 27

transferase

Question 28

catalyze hydrolysis of covalent bonds

Answer 28

hydrolases

Question 29

Form double bonds by the addition of removal of groups

Answer 29

lyase

Question 30

transfers a group intra-molecularly

Answer 30

isomerase (forms isomer)

Question 31

covalently links two molecules

Answer 31

ligase (ligate-to join together)