system
Medical AI Inquiry: You were designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.
user
Amino acid which contributes to biosynthesis of purine ribonucleotide are all EXCEPT:
assistant
The correct answer is  Ans. (b) HistidineRef: Harper's Biochemistry, 30th ed. pg. 340-42* N1 of purine is derived from amino group of aspartate* N3 & N9 are obtained from amide group of glutamine* C4, C5, & N7 of the purine ring of nucleotides are contributed by glycine.