Exam 2

Question 1

active site

Answer 1

that portion of an enzyme which is responsible for enzyme activity

Question 2

allosteric site

Answer 2

the location on an enzyme which is separate from the substrate binding site(s) and catalytic site(s) to which molecules bind and alter the activity of the enzyme

Question 3

Kcat - catalytic rate constant

Answer 3

is the rate constant for the conversion of the enzyme substrate complex into free enzyme and product.

Question 4

catalytic site

Answer 4

the location on an enzyme where the substrate(s) react with each other and/or portions of the enzyme

Question 5

dalton

Answer 5

a unit of molecular weight where 1 mole of hydrogen atoms is 1 dalton

Question 6

enzymology

Answer 6

the study of enzymes and their properties by measuring enzyme activity (kinetics)

Question 7

Vo - initial velocity

Answer 7

the rate of change in the concentration of substrate or product per unit time at the beginning of the reaction, where little product is formed when the back reaction is negligible

Question 8

isozyme

Answer 8

one of two or more enzymes which catalyze the same biochemical reaction and can be separated by some physical method e.g. electrophoresis or chromatography

Question 9

Km

Answer 9

is the concentration of substrate which yields half of the maximum velocity [Vmax] for an enzyme catalyzed reaction or is the concentration when the initial velocity is equal to half of the maximum velocity

Question 10

specificity

Answer 10

a measure of the uniqueness of a particular process

Question 11

substrate binding site

Answer 11

the location on the enzyme where the substrate binds to the enzyme

Question 12

Vmax

Answer 12

the rate of the enzyme catalyzed reaction with saturating concentrations of the substrate(s) and is the product of the catalytic rate constant or turnover number and the total enzyme concentration

Question 13

zymogen

Answer 13

an inactive precursor of an enzyme

Question 14

intermediates

Answer 14

a quasi-stable step between a substrate and product

Question 15

transition state analog

Answer 15

a stable molecule which resembles a proposed transition state

Question 16

transition state

Answer 16

the fleeting and unstable state of a substrate as it converted into product

Question 17

apoenzymes

Answer 17

the protein component of an enzyme which requires a cofactor for activity

Question 18

coenzymes

Answer 18

an organic cofactor

Question 19

cofactors

Answer 19

a non protein component which is required for enzyme activity

Question 20

cosubstrates

Answer 20

a coenzyme which is loosely bound to an enzyme and is consumed during the reaction

Question 21

holoenzymes

Answer 21

an apoenzyme plus its cofactor(s)

Question 22

metalloenzymes

Answer 22

an enzyme which contains one or more tightly bound metal ions which are essential for activity

Question 23

prosthetic groups

Answer 23

a coenzyme which is tightly bound to an enzyme and which is not consumed by the reaction

Question 24

simple enzymes

Answer 24

an enzyme which does not require a cofactor for activity

Question 25

Inhibitor

Answer 25

A molecule, when present, reduces the rate of a biochemical reaction, presumably by interaction with the catalyzing enzyme

Question 26

Acid-Base Catalysis

Answer 26

a type of enzyme mechanism when a proton is transferred from one substrate to another, from a substrate to an enzyme , or from an enzyme to a substrate.

Question 27

affinity

Answer 27

the attraction of one molecule to another

Question 28

covalent catalysis

Answer 28

a type of enzyme mechanism when a covalent bond is formed between a substrate and a substrate or a substrate and an enzyme which does not involve a proton

Question 29

enzyme

Answer 29

a biochemical catalyst- a molecule, usually protein, which increases the rate of a biochemical reaction with out affecting the equilibrium

Question 30

intermediate formation

Answer 30

a type of enzyme mechanism when intermediates are formed in between the transition from a substrate to a product

Question 31

proximity effect

Answer 31

a type of enzyme mechanism which involves limiting the movement and orientation (translation and rotation) of the substrate(s) with respect to each other or to the enzyme.

Question 32

transition state stabilization

Answer 32

a type of enzyme mechanism in which there is an increase interaction between the enzyme and transition state which lowers the activation energy and thereby increases the rate of reaction

Question 33

sugar

Answer 33

common name for carbohydrate

Question 34

saccharide

Answer 34

another name for carbohydrate

Question 35

carbohydrate

Answer 35

polyhydroxyl ketones or polyhydroxyl aldehydes and their derivatives

Question 36

anomers

Answer 36

a chiral center which is not initially present in a molecule and which is created by intramolecular bonding

Question 37

epimers

Answer 37

2 stereoisomers which differ only in 1 chiral center

Question 38

enantiomers

Answer 38

2 stereoisomers in which all chiral centers are switched

Question 39

isomers

Answer 39

2 different chemical compound which have same chemical composition but are physically distinct and separable

Question 40

diastereomers

Answer 40

stereoisomers which contain more than 1 chiral center but are not mirror images of each other