Lecture 3-5: Enzyme basics

Question 1

Edward buchner

Answer 1

yeast
sugar is converted to alcohol in yeast fermentation
oxidation to alcohol
discovered that using diff parts of yeast cell system that reaction still occurrs dont need whole yeast but yeast ferments r enough

Question 2

James sumner

Answer 2

first to crystalise a protein enzyme

urease

Question 3

haldane

Answer 3

enzymes must interact with substrate

Question 4

catabolism

Answer 4

breaking down

digestion respiration

Question 5

anabolism

Answer 5

take catabolised molecules n build em up again
biosynthesis
protein production

Question 6

biocatalysts vs inorganic catalysts i.e. Reynie Nickel, which is used to hydrogenate vegetable oils in industrial processes

Answer 6

enzymes have high specificity - avoids side roducts

mild reaction conditions condusive to conditions in cells

high reaction rates - biologically useful timeframes

capacity for regulation - control biological pathways

many potential pathways of decomposition

Question 7

EC system

Answer 7

1. Oxidoreductases - transfer of electrons
2. Hydrolases - hyrolysis reaction = transfer of functional groups to water
3. Lyases - cleavage f bonds by elimination, leaving double bonds or addition of groups to double bonds
4. isomerases - transfer of groups within molecules to yield isomeric forms
5. ligases - formation of bonds by condensation reactions couples to cleavage of ATP
6. transferases - group transfer reactions

Question 8

cofactors

Answer 8

small metal cation positively charged ion i.e Mg 2+, Fe2+, Cu2+,

Question 9

coenzyme

Answer 9

larger organic structures like prosthetic haem group NAD+ or CoA
biocytin help transfer Co2 found in biotin
CoEnzyme A help transfer Actyl groups

Question 10

holoenzyme

Answer 10

enzyme with its co factor an coenzyme

Question 11

apoenzyme

Answer 11

enzyme without coenzyme or cofactor

Question 12

phenylalanine hydroxylase metabolism

Answer 12

adds hydroxyl group top of phenyl ring

@ D form - no binding

Question 13

the reaction coordinate

Answer 13

Linear depiction of substrate binding to enzyme, intermediate and product
E + S = ES = EP = E+ P

Question 14

Gibbs free energy

Answer 14

no. of bonds + type of bonds = molecules total energy

substrate - ground state
product different gibb energy to substrate
change in G

enzymes do not affect equilibrium
slow reactions have high activation energies
enzymes decrease transition energy that needs to be paid to increase reaction rates

Question 15

the equilibrium constant

Answer 15

the ratio of Kon/Koff is the equilibirum constant Keq
Keq = [p]/[s]
enzymes increase the speedrate of k on and koff

Question 16

how do Keq and delta G fit together

Answer 16

delta G KJ/mol= -RT*lnKeq
R= gas constant 8.135J/molK
T=temp k

Question 17

how to lower delta G

Answer 17

enzymes have evolved to have binding sites to transition states best since its a 5050 state
and binds better than substrates
binds the substrate that has the transition position and active site forces it to adopt the correct structure to be in the transition state

Question 18

support for the proximity / transition state model

Answer 18

formation of anhydride bond
from ester and carboxylate
strong dependence on proximity of 2 reactive groups