When transketolase acts on fructose-6-phosphate and glyceraldehyde-3-phosphate,the products are
A) 3-phosphoglycerate and two molecules of glyceraldehyde-3-phosphate.
B) dihydroxyacetone phosphate and glucose-6-phosphate.
C) xylulose-5-phosphate and erythrose-4-phosphate.
D) xylulose-5-phosphate and ribose-5-phosphate.

Question

Quizplus · Accepted Answer

Transketolase catalyzes the transfer of two-carbon units between sugar phosphates. When it acts on fructose-6-phosphate and glyceraldehyde-3-phosphate, the products are xylulose-5-phosphate and erythrose-4-phosphate. This reaction is part of the pentose phosphate pathway, which generates NADPH and ribose-5-phosphate for nucleotide synthesis. Option A is incorrect because it suggests the formation of a glycolytic intermediate, 3-phosphoglycerate, which is not part of the pentose phosphate pathway. Option B is incorrect because it suggests the formation of two glycolytic intermediates, dihydroxyacetone phosphate and glucose-6-phosphate, which are not involved in the pentose phosphate pathway. Option D is incorrect because it suggests the formation of xylulose-5-phosphate and ribose-5-phosphate, which could be products of other reactions in the pentose phosphate pathway, but not the reaction catalyzed by transketolase.

When Transketolase Acts on Fructose-6-Phosphate and Glyceraldehyde-3-Phosphate,the Products Are