Enzymes

Catalysts are mostly proteins and they are:-

1. Efficient- work at body temperature in aqueous solution, near neutral pH. It can increase the rate of reaction by a factor of up to 1020.
2. Specific- each enzyme has a limited range of substrates, some can distinguish stereoisomers
3. Potent- each enzyme molecule can convert many substrate molecules into product per second

Enzymes speed up the rate at which a reaction reaches equilibrium 1) Bind and stabilize the transition state 2) Reduce activation energy by providing an alternative reaction pathway

Isoforms of enzymes - catalyze the same reaction but have different properties and structure

Protein kinases are molecules that facilitate phosphorylation reaction.

Metal ions required for enzymatic activity

Organic molecules required for enzymatic activity

Tightly bound coenzymes

enzyme without cofactor

Enzyme with cofactor

The substrate binds to an active site which is a cleft or crevice. It contains amino acids essential for catalytic activity and amino acids for highly specific interactions.

Active site of unbound enzyme is complementary to the shape of the substrate

Binding of a substrate induces a conformational change in the enzyme and it results in a complementary fit

1. Each enzyme will have an optimum - at either side of the optimum, enzyme activity will decrease
2. Active site can be altered by extreme temperature/pH