LF130 Lectures 23-26 (enzymes)

apoenzymes

enzymes lacking an essential cofactor

holoenzyme

enzyme and co factor complex

Kcat

no. molecules of one substrate that an enzyme can convert into product per second

EC1

oxidoreductases- oxidation/reduction

EC2

transferases- move functional groups from substance to substance

EC3

hydrolases- formation of 2 products by hydrolysis

EC4

lyase- non hydrolytic addition or reduction

EC5

isomerase- intermolecular rearragement

EC6

ligase- ATP dependant bond synthesis

EC7

translocase- movement across membranes

When and who lock and key?

Fischer, 1890s

When and who induced fit?

Koshland, 1958

enzyme rate constant

velocity is proportional to the conc of enzyme and substrate

Michealis- Menton definition

initial rate of an enzyme catalysed reaction as a function of the inital substrate concentration

michealis menton equation

Vo = Vmax x [S] / (Ks + [S])

Haldane and Briggs

process equation into theorectiall deviation

Haldane and Briggs equation

K2 [S] [Et] / Km + [S]

Km

substrate conc that gives half of enzyme active sites are occupied

Lineweaver and Burk’s graphs

by inversing MM equation, they show that a linear equation can be created using y=mc+c, allowing it to be solved

Allosteric regulation of DNA bases

In this example, creating purines created ATP which increased ATcase, which increases pyramindines which created CTP which decreased ATcase, creating a balance.

Enzymes in farming

weed control via the shikimate pathway which creates essential amino acids. it can be used to target weeds if crops are GM to resist it.

enzymes in food

used in fermentation and the creation of synthetic sugars like fructose.

enzymes in biosensors

electronic readouts based on enzyme action e.g glucose levels in diabetics