Transcript Lecture 10 - Sites@UCI

Lecture 10
Web: pollev.com/ucibio
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Km, Vmax, V0 – What do they all mean?
Parameters for enzyme action
Rates and regulation!
1. Km
[S] at which rate is ½ of VMax
NOT
________ of enzyme for substrate
High Km = ?
Physiological relevance of KM
Coordination of metabolism:
Glucose  Energy
Glucose  Glycogen
First step in both = Glc  Glc-6-PO4
Some tissues store, others need energy
Convert Glc  Glycogen only when [Glc] high?
2. VMax
Compare rates of reaction at given [S]
Some idea of efficacy of enzyme
Regulation
3. kCat
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
http://upload.wikimedia.org/wikipedia/commons/thumb/f/fb/Comp_inhib.svg/800px-Comp_inhib.svg.png
Allosteric noncompetitive inhibitor
http://upload.wikimedia.org/wikipedia/commons/thumb/5/55/Non-competitive_inhibition.svg/536px-Non-competitive_inhibition.svg.png
Allosteric competitive inhibitor
http://upload.wikimedia.org/wikipedia/commons/thumb/0/0f/Allosteric_comp_inhib_1.svg/800px-Allosteric_comp_inhib_1.svg.png
Allosteric competitive inhibitor
http://upload.wikimedia.org/wikipedia/commons/thumb/a/a2/Allosteric_comp_inhib_2.svg/800px-Allosteric_comp_inhib_2.svg.png