Mcb 102 Set 2

Front 1

Myoglobin

Back 1

-Located in Sarcoplasm ( cytoplasm of multinecleate muscle cell)

Front 2

Heme

Back 2

prosthetic group

Front 3

confirmational chanage in heme

Back 3

-pucker- hemoglobin bends out to bind to proximal his

02 pulls iron back to center from other face of heme

-distal his pulls O2 away preventing oxidation

Front 4

Hemoglobin

Back 4

-2 alpha 2 beta heterotetramer

-O2 binding can be measure photospectrometerically at 580nm

Front 5

Kd

Back 5

[P][L]/[P-L]

Front 6

Theta

Back 6

occupied sites/ total sites

[P-L]/([P-L]+[P])= [L]/([L]+Kd)

O2/(O2+Kd)

pO2/(pO2+p50)

Front 7

Michaelis-Menten'Equaton

Back 7

where V0 is the instantaneous change of concentration of Product over time

Front 8

Oxidoreductases

Back 8

remove hydrogen atoms from (oxidize) a donor molecule and concomitantly add hydrogen atoms to (reduce) an acceptor molecule.

Front 9

Transferases

Back 9

transfer a group of atoms (such as an acetyl moiety or a phosphoryl group) from one
molecule (usually an "activated" donor) to another molecule (acceptor). Such enzymes can also catalyze the attachment of such substituents as amino groups or acyl chains to other molecules.

Front 10

Hydrolases

Back 10

cleave a bond by adding the atoms of a water molecule across it. Such enzymes catalyze the hydrolysis of the anhydride bonds in all biopolymers, namely proteins (amide bonds),
polysaccharides (glycoside bonds), lipids (ester bonds), and nucleic acids (phosphodiester bonds).

Front 11

Lysases

Back 11

remove a group of atoms (like CO2 or H2O) from a substrate, leaving a double bond; or,
conversely, add a group of atoms across a double bond. Such enzymes include those that can add (or remove) a group HX (where X is a substituent other than OH) across alkene, imine, and carbonyl bonds.

Front 12

Isomerases

Back 12

change the relative configuration of atoms within a molecule with respect to one another
without changing the total number of atoms. Such enzymes can carry out epimerization, racemization, and
other interconversions of stereoisomers.

Front 13

Ligases

Back 13

join two previously separate molecules together, using the energy derived from cleavage of
a pyrophosphate bond in ATP to drive the reaction. Such enzymes can lead to formation of C-O, C-N, C-S, and C-C bonds.

Front 14

Bohr effect

Back 14

Acidity and higher CO2 concentration causes Hb to release O2

-in muscles where CO2 and H+ concentrations are high, the hemoglobin will relase O2 to help

Front 15

Explain the saturation curve of Hb

Back 15

sigmoidal: When it starts to bond, the affinity increases, afterwards is it rate dependent then it decreases

Front 16

Dihydrofolate reductase

Back 16

When dUMP turns to DTMP which turns to DNA

- DHFR turns NADPH+ H+ --> NADP

Front 17

Hallmarks of enzyme-mediated catalysis

Back 17

1. Tremendous rate enhancement

2. Occurs under physiological conditions

3. Precise reaction: highly selective for substrates; stereo-specific products

4. Subject to metabolic regulation

Front 18

How does an active site expedite a chemical reaction

Back 18

1. Entropy gain from substrates shedding water of solvation and displacing water bound in active site

2. Molecular complementary

3. H-bonds and salt bridges between groups on substrates and side chains in the active site are stronger in the absense of competition or shielding by water

4. Binding at the active site holds the substrates in close procimity

5. some binding energy expended to introduce strain into bonds into induced fit

Front 19

linear plot of Michaelis Menten eqn

Back 19

Front 20

Kcat

Back 20

same as k2, turnover number per second

Front 21

Specificity constant

Back 21

Kcat/Km

A good enzyme has a high Kcat and a low Km

Front 22

Reversible inhibitors (4 types)

Back 22

Do not covalently react with enzyme

(1) Competitive (Transition state analogues) Vmax constant, Km --> alpha(Km)

(2) Uncompetitive (Lowers Vmax, Lowers Km)

(3) Mixed inhibition (binds both to enzyme and enzyme substate complex) EI <--> ESI as well, increases Km, decreases Vmax

(4) Noncompetitive inhibitors (special case where Ki = Ki') Km doesn't change

Front 23

Progression from primary polypeptide to mature protein: alpha Chymotrypsin

Back 23

-Hydrophobic chain at beginning acts as "baggage ticket" to enter cell

Front 24

Km

Back 24

(kr+kcat)/(kf)

kr=enzyme unbinding

kcat=product formation

kf=enzyme binding

Front 25

What is the molecular structure of Sarin

Back 25

Front 26

Group specific reagents

Back 26

Front 27

Reactive substrate analogs

Back 27

Front 28

Suicide (Mechanism-based) inhibitors

Back 28

Nonreactive until substrate starts to react with it

Catalysis generates the compound to make the enzyme become inactive

Front 29

Configuration of active site of chymotrypsin

Back 29

Asp102...His57-NH2... HO-Ser195

Front 30

Acylation 1

Back 30

Front 31

Acylation 2

Back 31

Front 32

Deacylation 1

Back 32

Front 33

Deacylation 2 (final step of mechanism)

Back 33

Front 34

Threonine products

Back 34

Hydro xyethyl _TP

same enzyme uses 3 subsrates to create Ille , Val, Leu

Front 35

K allosteric enzyme

Back 35

small, sigmoidal curves

adding substrate --> more active sites

substate is an allosteric effector, makes binding to subrate easier.

Inhibitor Km increases, substrate to the left

vmax stays the same

Front 36

Confirmational preferences

Back 36

Front 37

multiple isozymes subject to independent feedback inhibition (E-T)

Back 37

Front 38

How T, I, and V are kept in balance

Back 38

Front 39

V allosteric enzyme

Back 39

Vmax changes but Km stays the same

inactive state binds just as well as active state, but won't make product

Front 40

ATCase

Back 40

dodecomer with catalytic trimer and regulatory dimer stacked twice

PALA is a bisubstate analog that can activate by conformational change in low concentrations

like Hb, has a sigmoidal curve

Front 41

Enzyme regulation by reversible phosphorylation

Back 41

Front 42

Name the three types of irreversible inhibitors

Back 42

-Reactive substrate analogues (Tosyl Phenylalanine Chloromethyl Ketone, Histidine of Chymotrypsin)

-Group-specific reagents (Bromoacetol phosphate, reacts with glutamine) OR (DIPF, inactivates Acetylcholin esterase)

-Suicide (mechanism-based) inhibitors

Front 43

Amino acids most likely to adopt alpha conformation

Back 43

Q, A, L, M, E, K, R, H

Front 44

Amino acids most likely to adopt Beta strand

Back 44

V, I, Y, C, W, F , T

Front 45

Amino acids most likely to adopt reverse turn

Back 45

G, N, P, S, D

Front 46

Assay for hemoglobin saturation

Back 46

Spectrophotometer-- oxygenated hemoglobin absorbes at 580 peak

Front 47

Y axis of hill eqn

Back 47

log (theta/1-theta)