Lecture 10 Web: pollev.com/ucibio Text: To: Type in:

K m, V max, V 0 – What do they all mean? Parameters for enzyme action Rates and regulation!

1. K m [S] at which rate is ½ of V Max NOT ________ of enzyme for substrate High K m = ?

Physiological relevance of K M Coordination of metabolism: Glucose  Energy Glucose  Glycogen First step in both = Glc  Glc-6-PO 4 Some tissues store, others need energy Convert Glc  Glycogen only when [Glc] high?

2. V Max Compare rates of reaction at given [S] Some idea of efficacy of enzyme Regulation

3. k Cat Also an idea of rate #molecules converted per second Time per conversion

Enzyme regulation Structurally, how can we regulate enzymes?

Enzyme regulation: Terms Allosteric Homotropic Heterotropic Reversible Irreversible

Competitive inhibition

Allosteric noncompetitive inhibitor

Allosteric competitive inhibitor

Allosteric competitive inhibitor