UCM Biochem Chap 5, 6, 11

The energy difference between rxn and transition state is called

activation energy

In an enzyme catalyzed rxn …. occurs when the [ES] is constant

steady state

When the substrate concentration is equal to …. the rxn velocity is equal to half the max velocity

Km

k2/[Etot] =

Vmax

Metal ions are able to generate a strong …. in enzyme catalyzed rxns

nucleophile

glycogen is polymer of glucose linked by … and … glycosidic bonds

alpha - 1,4 and 1,6

A rxn can occur spontaneously only if delta G is ….

negative

When delta G for a system is zero, the system is at

equilibrium

The enzyme location that carries out catalyst is called the

active site

Sucrose contains ……… glycosidic bond between fructose and glucose.

Fru B-1, alpha-1 Glu

The phenomenon in which some enzymes undergo a conformation change upon binding substrate is called…..

induced fit model

…… is a method of catalysis involving the correct positioning of substrates with respect to each other

position/orientation catalysis

List the three distinctive features of enzyme

1.power - enzyme speed up the rxn up to 10 to 27, 2. regulation - enzyme are regulated with inhibitors and equilibrium, 3. specificity - each enzyme only reacts to 1 substrate for 1 rxn

What kind of inhibitor is chymotrypsin in indole?

competitive??

What effect on observed values of Km and Vmax would you expect for chymotrypsin catalyzed rxn, if indole was present in solution?

Vmax will stay the same, Km will increase

The transition state substrate equilibrium constants for an uncatalyzed chemical rxn are given below. Assuming the rxns occur at 25 degree C calculate the activation energy for the uncatalyzed rxn.

Keq(uncat) = 3.78 × 10^-12

Keq(cat) =7.52 × 10^-8

work it out

Ea = -RTlnKeqcat = kJ/mol

Calculate the velocity enhancement of catalyzed versus the uncatalyzed rxn

Keq(cat)/Keq(uncat) =

rxn happens … times faster or slower

Draw beta D-Fructose

Draw ribose

Draw dihydroxyacetone

Draw alpha D-Galactose

Draw maltose

Elastace uses aspartic acid, histidine, and serine to catalyze the hydrolysis of peptide bonds. List the methods of catalyze each amino acids performs during the rxn.

Serine:

covalent catalysis - acts a nucleophile and attaches the peptide bond

Elastace uses aspartic acid, histidine, and serine to catalyze the hydrolysis of peptide bonds. List the methods of catalyze each amino acids performs during the rxn.

Histidine:

acid-base catalysis - takes hydrogen from serine to make it a nucleophile then gives that hydrogen to the N-terminus of the new peptide during the burst phase of the rxn

Elastace uses aspartic acid, histidine, and serine to catalyze the hydrolysis of peptide bonds. List the methods of catalyze each amino acids performs during the rxn.

Aspartic acid:

orientation and position - (stabilize and positions) the (-) charge keep histidine position via hydrogen bonding with the NH group

Glycerol-3-phosphate can undergo a hydrolysis rxn to create glycerol and inorganic phosphate.

In principle, the phosphate group could be removed by the cleavage of either the P-O bond or the C-O bond. These two possibilities can be distinguished experimentally by the use of H2O labeled with O^18 as a substrate.

Name the product which would be labeled with 18^O if the P-O bond is broken?

Name the product which would be labeled with 18^O if the C-O bond is broken?

phosphate, glycerol

Glycerol-3-phosphate can undergo a hydrolysis rxn to create glycerol and inorganic phosphate.

In principle, the phosphate group could be removed by the cleavage of either the P-O bond or the C-O bond. These two possibilities can be distinguished experimentally by the use of H2O labeled with O^18 as a substrate.

Propose a plausible mechanism for this rxn. Choose the correct bond to break. You must use at least two different two AA chains, draw them correctly once and name the AA and for proposing a plausible rxn mechanism

Draw mechanism

Using the graph on the final page answer the following question:

Estimate Km or Kmapp and Vmax for each set of conditions, unit are required. Determine what type of inhibitor molecule A is.

Using graph, using the michaels menten equation calculate the fraction of enzyme that has substrate bound to it when the substrate concentration is 324 microM for condition S.

Vo/Vmax = [S]/Km + [S] = Y trait bound