Lecture 9

Hydrolases Transferases Oxidoreductases Lyases Ligases Isomerases

catalyze hydrolysis reactions

move a group, such as an amino group

promote oxidation/reduction reactions

remove a group, but not by hydrolysis

create new bonds

inter-convert isomers

Trivial names formed from the substrate, then the type of reaction, along with the ending: –ase

Enzymes that have evolved slightly different amino acid sequences Act on the same substrate, but may be secreted from different types of tissues function best at different pHs

5 isoforms

the protein portion of an enzyme Not functional because it lacks a cofactor

a non-functional form of an enzyme can be converted into a functional form, often by hydrolysis of a group(s)

an inorganic species that is required for the function of an enzyme

an organic cofactor called a prosthetic group if it is tightly bound Many coenzymes are vitamins

Enzyme Activity is determined by an assay instead indicates how much of the enzyme is functioning in the sample Measured as U or IU of enzyme

enzymes detected in serum

trauma cell death caused by a disease

enzyme that phosphorylates creatine into creatine phosphate (CP)

CK-MM: found in skeletal muscles CK-MB: found mostly in the heart CK-BB: found mostly in the brain and smooth muscle

enzyme that promotes the oxidation of lactate to pyruvate

Mostly found in bone, kidneys and intestines Promotes dephosphorylation under alkaline (basic) conditions

bone calcification Elevated ALKP in several bone diseases and during healing of broken bones

Children, growth spurts

largest amount is in the prostate Promotes de-phosphorylation under acid conditions