2.4.2 Enzyme Regulation

Question 1

Isozyme (with LDH and CO1/COX2 examples)

Answer 1

-Enzymes differing in amino acid sequence that facilitate the same reaction
-Lactate Dehydrogenase (5 types with different subunits represented by H and M and can be separated via gel electrophoresis indicating differences in charges/active site side chains)
H subunit predominates in heart facilitates lactate converted backwards to pyruvate
M in skeletal muscle and facilitates transport of lactate to liver for gluconeogenesis

-COX1 and COX2 isozymes for arachidonic acid to prostaglandin (inflammation and pain) Aspirin and Ibuprofen inhibit both isozymes causing GI SEs, active sites differ Ile to Val in COX2 so target COX2 to avoid GI SEs for more targeted drug(Celebrex, Vioxx)

Question 2

Protease production

Answer 2

1) Prepro-enzyme (translated from leader sequence on mRNA for location) inactive, transported to right location to form
2) Pro-enzyme (zymogen), leader sequence cleaved to form
2) Mature Protease, other region of the protease cleavd to active form

example: Trypsinogen secreted from pancreas, transported to small intestine where leader sequence is cleaved by enteropeptidase to form active Trypsin

Question 3

Protease production

Answer 3

1) Prepro-enzyme (translated from leader sequence on mRNA for location) inactive, transported to right location to form
2) Pro-enzyme (zymogen), leader sequence cleaved to form
2) Mature Protease, other region of the protease cleaved to active form

example: Trypsinogen secreted from pancreas, transported to small intestine where leader sequence is cleaved by enteropeptidase to form active Trypsin