Mcat Biochemistry Chapter 2

Front 1

oxidoreductase

Back 1

catalyze oxidation-reduction reactions that involve transfer of electrons

Front 2

transferases

Back 2

move a functional group from one molecule to another

Front 3

hydrolases

Back 3

catalyze cleavage with the addition of water

Front 4

lyases

Back 4

catalyze cleavage without addition of water and without the transfer of electrons. reverse reaction (synthesis) often more important biologically

Front 5

isomerases

Back 5

catalyze interconversion of isomers, including both constitutional isomers and stereoisomers

Front 6

ligases

Back 6

responsible for joining two large biomoleculues, often of the same type

Front 7

exergonic reactions

Back 7

release energy, delta G is negative

Front 8

enzymes act by

Back 8

stabilizing transition state, OR

providing favorable microenvironment, OR

bonding with the substrate molecules

Front 9

site of catalysis on enzyme

Back 9

active site

Front 10

lock and key theory

Back 10

enzyme and substrate are exactly complementary

Front 11

induced fit model

Back 11

enzyme and substrate undergo conformational changes to interact fully

Front 12

saturation kinetics

Back 12

as substrate concentration increases, reaction rate does as well until a maximum value is reached

Front 13

Km

Back 13

concentration of substrates when the reaction reaches half of Vmax

Front 14

Vmax

Back 14

maximum rate of reaction, when enzyme is totally saturated with substrate

Front 15

feedback inhibition

Back 15

regulatory mechanism whereby catalytic activity of an enzyme is inhibited by the presence of high levels of a product of the reaction

Front 16

reversible inhibition

Back 16

ability to replace the inhibitor with a compound of greater affinity, or to remove it using mild laboratory treatment

Front 17

competitive inhibition

Back 17

inhibitor is similar to the substrate and binds at the active site. can be overcome by adding more substrate (vmax unchanged, km increases)

Reversible

Front 18

non-competitive inhibition

Back 18

inhibitor binds with equal affinity to the enzyme and the enzyme-substrate complex

Vmax decreases, Km unchanged

Reversible

Front 19

mixed inhibition

Back 19

inhibitor binds with unequal affinity to the enzyme and the enzyme-substrate complex

vmax decreased, Km increased or decreased depending on if the inhibitor has higher affinity for enzyme or enzyme-substrate complex

Reversible

Front 20

uncompetitive inhibition

Back 20

inhibitor binds only with the enzyme-substrate complex

Km and Vmax both decrease

Reversible

Front 21

irreversible inhibition

Back 21

alters enzyme in such a way that active site is unavailable for a prolonged duration or permanantly

Front 22

allosteric site

Back 22

can be occupied by activators, increasing affinity or enzymatic turnover

Front 23

zymogens

Back 23

regulatory enzymes that are secreted in an inactive form, activated by cleavage