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Flashcards in enzymes Deck (39):
1

biological catalyst that functions to speed up the rate of a biological reaction, but is not altered or consumed in the reaction

enzyme

2

energy needed for the reaction to go to completion

activation energy

3

the substances upon which an enzyme acts

substrates

4

the substances produced by chemical modification of substrates

products

5

the specific region on/in an enzyme where substrates bind and where the catalytic reaction occurs

active site

6

the unstable "energized" intermediate formed in an enzymatic reaction that has properties of both the substrate and the product

transition state

7

three things enzymes do to lower the activation energy

orienting/holding substrates very close together
creating/stabilizing the transition state intermediate
facilitating the reaction via reactive amino acids in the active site

8

the model that suggests the enzyme active site perfectly matches the shape of the substrate and so the enzyme allows only one substrate to bind to the active site

lock and key model

9

model that suggests substrates fit to active site like a flexible hand in glove, the enzyme-substrate binding changes the shape of both the enzyme and the substrate to fit snugly

induced fit model

10

catalyze oxidation-reduction reactions; add/remove electrons from its substrate

oxidoreductases

11

transfer a functional group from one molecule to another

transferases

12

cleave bonds by adding a water molecule

hydrolases

13

remove functional groups via non-hydrolytic reactions

lyases

14

catalyze rearrangements of functional groups within a molecule

isomerases

15

use the energy from ATP hydrolysis to form bonds between two substrate molecules

ligases

16

EC 1-6

1. oxidoreductases
2. transferases
3. hydrolases
4. lysases
5. isomerases
6. ligases

17

loosely bound non-protein components of enzymes that assist in catalytic reactions

cofactor

18

two main types of cofactor

organic and inoganic

19

tightly bound non-protein components of proteins

prosthetic groups

20

hydrolyzes cellulose, used as a digestive aid and in biofuel production

cellulase

21

hydrolyzes collagen, promotes burn and would healing

collagenase

22

hydrolyzes sucrose, used in the manufacture of soft-centered candy

intertase

23

hydrolyzes lipids, used as a digestive aid and improves the flavor of cheese

lipase

24

hydrolyzes pectin and clarifies fruit juice

pectinase

25

hydrolyzes protein and used in detergents

protease

26

the maximum possible velocity that a reaction can have at infinite substrate concentration

V max

27

the half maximal velocity of a reaction

1/2 V max

28

the substrate concentration at which the enzyme has half maximal velocity

Km

29

which velocities are the most relevant

the initial velocities

30

reaction velocities ____ with time

slow down

31

three reasons why enzymes rarely operate at true V max

substrate in most cells is not high enough
little or no regulation by substrate at V max
substrate at Km is more realistic

32

an indication of enzyme affinity for substrate

Km

33

enzymes with ____ have greater substrate affinity

lower Km's

34

what are the axis for the lineweaver-burk equation graph

x axis: 1/substrate conc.
y axis: 1/v

35

the amount of enzyme that produces one mole of product per minute

enzyme unit

36

amount of enzyme that produces one mole of product per second

katal

37

micromoles of product formed per minute per mg protein

specific activity

38

the number of substrate molecules converted to product per unit time by a single molecule of enzyme

turnover number (Vmax/[Enz])

39

an estimate of how perfect the enzyme is or how well the enzyme performs when S is low

catalytic efficiency (Kcat/Km)