Lecture 10

Question 1

What enzyme catalyzes the transfer of a C-, N-, or P- containing groups

Answer 1

Transferases

Question 2

What enzyme catalyzes the cleavage of bonds by addition to water

Answer 2

Hydrolases

Question 3

What enzyme catalyzes the cleavage of a C-C, C-S, and certain C-N (without water)

Answer 3

Lyases

Question 4

What enzyme catalyzes racemization of optical/ geometric isomers?

Answer 4

Isomerases

Question 5

What enzyme catalyzes the formation of bonds between carbon and an N,O,S,C coupled to hydrolysis of high-energy phosphates

Answer 5

Ligase

Question 6

_______ is a small molecule required for the
catalytic activity of an enzyme.

Answer 6

Cofactor

Question 7

________ (inorganic) include Cu2+, Fe3+ or Zn2+

Answer 7

Metal ions

Question 8

When the cofactor is an organic molecule, then
it is a ________. E.g.: vitamins

Answer 8

Coenzyme

Question 9

When the coenzyme is only transiently
associated, then it is a_________

Answer 9

cosubstrate

Question 10

When the coenzyme is permanently associated with the protein, either through covalent or non-covalent interactions, then it is a __________

Answer 10

Prosthetic group

Question 11

_________ is the catalytically active enzyme-cofactor complex.

Answer 11

Holoenzyme

Question 12

________ is the inactive protein lacking the cofactor.

Answer 12

Apoenzyme

Question 13

_________ is a small molecule that binds to a larger one

Answer 13

Ligand

Question 14

_________ is the molecule undergoing the reaction. It is the specific molecule(s) that is bound by the enzyme at its active site.

Answer 14

Substrate

Question 15

___________ is the region of the enzyme that binds the substrate(s) and where the ________ takes place.

Answer 15

Active site, catalytic reaction

Question 16

In our cells, groups of enzymes work
together in specific metabolic pathways
consisting of several steps. They are called
___________

Answer 16

Multi-enzyme pathways.

Question 17

Multi-enzyme pathways can be _______ or
_____________, and they are all __________.
Since some metabolites are shared among
pathways, the fate of a certain metabolite
affects the other pathways.

Answer 17

Linear, branched, interconnected

Question 18

The slowest step in the pathway
is the _____________.

Answer 18

Rate-limiting step

Question 19

______________ catalyze the slowest, irreversible step

Answer 19

Rate-limiting enzymes

Question 20

Rate-limiting steps are targets of _________
and targets of ________ by drugs

Answer 20

Regulation, intervention

Question 21

Organelles preventing a _______ in enzyme pathways with common products, separating by space

Answer 21

Futile cycle

Question 22

Seperation in time: Glucose breakdown (glycolysis)
and synthesis (gluconeogenesis) share
enzymes in the same compartment,
but have different ________

Answer 22

Rate-limiting steps

Question 23

The concentration of many regulatory enzymes
is controlled by ______ and _____

Answer 23

Inducers and inhibitors

Question 24

Enzyme synthesis is a

Answer 24

Very slow process

Question 25

Compartmentalization is an important but ________ of regulation

Answer 25

Passive means

Question 26

Product inhibition; Products display ______ to the
substrate, and cannot be competed off by the
substrate.

Answer 26

Structural similarity

Question 27

Product inhibition- Products can bind _______ to the active site. The response of the enzyme is _______.

Answer 27

Reversibly, immediate

Question 28

Facts about allosteric regulators

Answer 28

They have quaternary structure, effector binds at a regulatory site (not active site), they bind reversibly, no need for structural similarity, show sigmoidal curve

Question 29

Allosteric regulation of enzymes: Classification is based on

Answer 29

Chemical nature of the effector

Question 30

Allosteric regulation of enzymes;
__________ = true substrate.
__________ = different chemical nature from true substrate.

Answer 30

Homotropic, heterotropic

Question 31

Allosteric activators (positive effectors) have what effect on enzyme activity, enzyme state, enzyme activity curve

Answer 31

Increase activity, stabilize R-state, shift left

Question 32

Allosteric inhibitors (negative effectors) have what effect on enzyme activity, enzyme state, enzyme activity curve

Answer 32

Decrease activity, stabilize T-state, shift right

Question 33

_______________: upstream substrate of a multi-enzyme pathway activates a downstream enzyme.

Answer 33

Feedforward activation

Question 34

Disease of the day: Pulmonary emphysema may be produced by ______________. As A1A is defective, that leads to increased __________ activity.

Answer 34

alpha1-antitrypsin deficiency (A1AD), neutrophil elastase

Question 35

What are major risk factors for a1-Antitrypsin deficiency, and where does it effect

Answer 35

Smoking, lungs and liver

Question 36

Covalent regulation refers to the ________ of specific chemical groups via _______ bonding. They have an ________ effect, either reversible or irreversible. They may _________ enzymatic activity, depending on the enzyme considered.

Answer 36

Addition or removal, covalent, immediate, increase or decrease

Question 37

Many enzymes are produced in an inactive precursor form called ________

Answer 37

Proenzyme or zymogen

Question 38

Proteolytic cleavage results in an _________ conformational change that exposes the active site

Answer 38

Irreversible