Biochem Exam 2 (Part Two)

Front 1

What are high levels of creatine kinase in serum an indication of?

Back 1

Muscular dystrophy

Front 2

Enzymes alter the _____ of the reaction not the ____ ____

Back 2

Enzymes alter the rate of the reaction not the equilibrium constant

Front 3

How fast do enzymes work?

Back 3

Increases rate between 10^8 to 10^12

Front 4

What is the enzymatic turnover number (moles product/moles active site/sec)

Back 4

~20 per second

Front 5

____ and ___ usually stay tightly bound to the enzyme

Back 5

FAD and FMN

Front 6

What is the cofactor that reversibly binds to an enzyme

Back 6

NADH

Front 7

Active site

Back 7

The region of the enzyme where chemical reaction occurs.

Front 8

Allosteric

Back 8

"other" then the active site

Front 9

Oxidoreductase

Back 9

Oxidation-reduction reaction

Front 10

CH3CH2OH -> CH3CHO

Back 10

Oxidation-reduction reaction

Front 11

Transferase

Back 11

Transfer of a group (eg PO4)

Front 12

Hydrolase

Back 12

Addition of water, cleavage

Front 13

Lyase

Back 13

Cleavage by elimination

Front 14

Isomerase

Back 14

Cause of isomerization

Front 15

Ligase

Back 15

Coupling two molecules, ATP hydrolysis

Front 16

What are the two types of bisubstrate reactions?

Back 16

Random (By-By) and Ordered (Ping-Pong)

Front 17

How are most pathways regulated?

Back 17

Via an irreversible step

Front 18

What is the rate determining step?

Back 18

The slowest step

Front 19

What are the types of catalysis?

Back 19

Acid-base, covalent, metal ion, proximity and orientation, transition state stabilization, electrostatic effects

Front 20

What are metalloenzymes?

Back 20

The metal remains tightly bound to the enzyme. FE2+, FE3+, Cu, Zn, Mg, Co

Front 21

What metals do enzymes not remain tightly bound?

Back 21

Na, K, Mg, Ca

Front 22

What is transition state binding?

Back 22

The binding of substrates to the active site promotes straining so that the transition state is formed, these generally bind more tightly to enzymes.

These often make good therapeutic agents.

Front 23

What is electrostatic catalysis?

Back 23

The distribution of charges in an active site, which influences the stability of the transition state and the pKa of amino acid side chains.

Front 24

What is a reversible enzyme inhibitor?

Back 24

Inhibitor binds reversibly to enzymes (binding may be tight and seem irreversible under physiological conditions)

Front 25

What is an irreversible enzyme inhibitor?

Back 25

Inhibitor reacts covalently with the enzyme

Front 26

What are the types of reversible inhibition?

Back 26

Competitive, non-competitive, uncompetitive, and mixed

Front 27

What is competitive inhibition?

Back 27

Competes with substrate for binding to the enzyme, causing an increase in Km. Often binds to same site as the substrate and resembles the substrate.

Front 28

What is non-competitive inhibition?

Back 28

Only Vmax changes

Front 29

What is mixed inhibition?

Back 29

Both Km and Vmax change

Front 30

How does penicillin work?

Back 30

Inhibits an enzyme involved in the synthesis of bacterial cell walls

Front 31

How does aspirin work?

Back 31

Inhibits (acetylates) prostaglandin synthesis (cyclooxygenase)

Front 32

What are two examples of the rational drug design?

Back 32

HIV protease inhibitors and Celebrex (COX II inhibitor)

Front 33

What does Amanitin inhibit?

Back 33

RNA polymerase II

Front 34

Can enzymes be made of RNA?

Back 34

Yes

Front 35

What is the active site

Back 35

site on enzyme where chemical change occurs

Front 36

What is the substrate

Back 36

molecule that the enzyme modifies

Front 37

What is the product?

Back 37

molecule that the enzyme produces

Front 38

What is a cofactor

Back 38

a small molecule required for activity

Front 39

What is a prosthetic group?

Back 39

A cofactor that is very tightly bound to the enzyme

Front 40

What is NADH

Back 40

A cofact that reversibly binds to the enzyme

Front 41

What is an apoenzyme

Back 41

An ezyme minus its prosthetic group (inactive)

Front 42

What is a holoenzyme

Back 42

The enzyme containing its prosthetic group (active)

Front 43

The substrate S and enzyme E combine to form ____

Back 43

a complex ES

Front 44

____ binds more tightly to enzymes than do substrates

Back 44

transition states

Front 45

What often make good therapeutic drugs?

Back 45

transition states

Front 46

What causes the formation of the transition state

Back 46

binding of the substrate to the active site promotes straining so that the transition state is formed

Front 47

How can competitive inhibition be overcome?

Back 47

Increase the substrate

Front 48

What does the majority of drug metabolism

Back 48

cytochrome P450

Front 49

What is in the endoplasmic reticulum cytochrome p450 reductase?

Back 49

FAD and FMN. FAD is the electron entry site, FMN is the electron exit site.

Cytochrome b5 - a small heme protein that can be involved in the electron transfer

Front 50

What is in the mitochondrial P450 system?

Back 50

Steroid hydroxylation reaction

cytochrome P450, NADH and FAD.

FAD is weakly associated and needs Adrenodoxin-two Fe-S clusters.

Front 51

How is P450 classified into familes and subfamilies?

Back 51

Based on amino acid sequences?

Front 52

Family members that share a 40% sequence homology are assigned a ___

Back 52

number

Front 53

Family members that share a 55% -99% homology are assigned ___

Back 53

a subletter

Front 54

How does alcohol affect CYP

Back 54

alcohol induces CYP

Front 55

What is the primary endogenous vasodilator?

Back 55

NO

Front 56

What is NO necessary for?

Back 56

maintenance of vascular tone, platelet aggregation, and neural transmission

Front 57

What is nNOS

Back 57

neuronal NOS - skeletal muscle and neurons

Front 58

What is NOSII

Back 58

iNOS - macrophage or induced

Front 59

What is NOSIII

Back 59

eNOS - endothelium (myristoylation, palmitoylation)

Front 60

What do all three isoforms of NO contain?

Back 60

a heme prosthetic group, FAD, and FMN, and tetrahydrobiopterin

Front 61

What is the electron donor for NO?

Back 61

NADH - electrons enter via FAD and exit FMN

Front 62

What is calmodulin

Back 62

a calcium binding protein - controls the flow of electrons from FMN to the heme

Front 63

What elements are required for NOS to have effect?

Back 63

Iron, zinc, calcium

Front 64

What is eNOS

Back 64

important for blood vessel tone, overproduction can cause hypertension and thrombosis, can be beneficial as a treatment for pulmonary arterial hypertension

Front 65

What is iNOS

Back 65

essential in tumorcidal and bacterialicidal functions of macrophage

Front 66

What is nNOS

Back 66

shows loss of control of intestinal muscle and resistance to ischemic injury, producing vascular stroke

Front 67

What NOS is dependent upon calcium?

Back 67

eNOS and nNOS

Front 68

What NOS is independent of calcium

Back 68

iNOS