Chapter 2- Enzymes Flashcards Preview

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Flashcards in Chapter 2- Enzymes Deck (35)
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1

zymogen

inactivated form of enzyme

2

Oxidoreductases

catalyze oxidation-reduction reactions (transfer of electrons between biological molecules). typically have cofactor that acts as electron carrier (ex: NAD+ or NADP+) reductant (electron donor), oxidant (electron acceptor)

3

oxidase

catalyze oxidation reduction reactions and typically have oxygen as the final electron acceptor

4

Transferases

catalyze movement of a functional group from one molecule to another. (kinases are included in this group- transfer of phosphate group, generally from ATP to another molecule)

5

Hydrolases

catalyze breaking of a compound into two molecules using the addition of water (ex: phosphatase- cleaves phosphate group from another molecule)

6

Lyases

catalyze cleavage of single molecule into two products. dont require water. typically referred to as synthases. (ex: ATP into AMP and inorganic phosphate)

7

Isomerases

catalyze rearrangement of bonds within a molecule.

8

ligases

catalyze addition or synthesis reactions generally b/w large similar molecules. often require ATP.

9

two enzyme theories (also note which is more supported)

lock and key theory induced fit model (more supported)

10

lock and key theory

enzymes active site (lock) is already in appropriate conformation for the substrate (key) to bind.

11

induced fit model

substrate induces a change in shape of the enzyme. requires energy so its endergonic to change shape, but to release the substrate from the enzyme is exergonic.

12

cofactors/coenzymes

nonprotein molecules that participate in catalysis of reaction. typically carry charge and recruited only when needed.

13

apoenzymes

enzymes without their cofactors

14

holoenzymes

enzymes containing cofactors

15

prosthetic groups with respect to enzymes

tightly bound cofactors or coenzymes that are necessary for enzyme function

16

cofactors

inorganic molecules/ metal ions (often ingested as dietary minerals)

17

coenzymes

small organic groups, vast majority are vitamins or derivatives of vitamins such as NAD+, FAD, and coenzyme A.

18

water-soluble enzymes

Vitamin B and C (ascorbic acid) are important and must be replenished regularly b/c they are easily excreted.

19

fat-soluble vitamins

Vitamin A, D, E, and K are better regulated by partition coefficients (quantify ability of a molecule to dissolve in polar/nonpolar environments.

20

saturation

when all available enzymes are working with substrates. this is where the enzymes are working at a maximal velocity as long as enzyme concentration stays constant.

21

Michaelis-Menten equation (with enzyme concentration constant)...how to find velocity of an enzyme

v = Vmax [S] / Km + [S]

22

when reaction rate is equal to half of Vmax

Km = [S]

23

Km (Michaelis constant)

substrate concentration at which half of the enzymes active sites are full

24

Km and enzymes affinity for substrate

low Km = high affinity high Km = low Km *note: Km cannot be changed, its an intrinsic property

25

Lineweaver-Burk plots

x-intercept: -1/Km y-intercept: 1/Vmax

26

T vs. R state

T (low affinity Tense state) R (high affinity Relaxed state)

27

enzymes and temperature

reaction rate doubles in velocity for every 10degree increase in temperature until optimum temperature is reached. (37 degrees for human body).

28

optimal pH in body

stomach- 2 pancreas- 8.5 rest of body- 7.4

29

feedback regulation

regulation of enzymes by products further down a given metabolic pathway

30

feed-forward regulation

regulation of enzymes by intermediates in the pathway