Question

An actively respiring bacterial culture is briefly incubated with [1-14^C] glucose, and the glycolytic and citric acid cycle intermediates are isolated.
1. Where is the 14^C in each of the intermediates listed below? Consider only the initial incorporation of 14^C, in the first pass of labeled glucose through the pathways.
i. Fructose-1,6-bisphosphate
ii. Glyceraldehyde-3-phosphate
iii. Phosphoenolpyruvate
iv. Acetyl-CoA
v. Citrate
vi. a-ketoglutarate vii. Oxaloacetate

Answer 1

Answer:

i) C-1

ii) C-3

iii) C-3

iv) C-2 (methyl group)

v) C-4

vi) C-4

vii) Equally distributed in C-2 and C-3.

Explanation:

i) In  Fructose-1,6-bisphosphate , initial incorporation of 14^C occurs at C-1

ii) In Glyceraldehyde-3-phosphate, initial incorporation of 14^C occurs at C-3

iii) In Phosphoenolpyruvate, initial incorporation of 14^C occurs at C-3

iv) In Acetyl-CoA, initial incorporation of 14^C occurs at C-2 (methyl group)

v) In Citrate, initial incorporation of 14^C occurs at  C-4

vi) In a-ketoglutarate, initial incorporation of 14^C occurs at C-4

vii) in Oxaloacetate, initial incorporation of 14^C occurs at Equally distributed in C-2 and C-3.