Which Calvin cycle enzymes would iodoacetate inhibit?
ribulose 5-phosphate epimerase, fructose 1,6-bisphosphatase, ribose 5-phosphate isomerase, and glyceraldehyde
3-phosphate dehydrogenase
ribulose 5-phosphate kinase, fructose 1,6-bisphosphatase, sedoheptulose 1,7-bisphosphatase, and glyceraldehyde
3-phosphate dehydrogenase
transketolase, ribulose 5-phosphate kinase, sedoheptulose 1,7-bisphosphatase, and ribose 5-phosphate isomerase
fructose 1,6-bisphosphatase, transketolase, ribulose 5-phosphate epimerase, and ribose 5-phosphate isomerase
Why would iodoacetate inhibit these enzymes?
Activation of the enzymes depends on the reduction of disulfide bonds between Cys residues to form free
-SH groups.
HI produced by the reaction of iodoacetate with Cys residues creates an acidic environment that denatures
the enzymes.
Acetylated Cys residues can no longer undergo phosphorylation which the enzymes require for activation.
Acetylated Cys residues cannot undergo oxidation to form the disulfide bonds these enzymes require for activation.
