<prompt> Amino acid which contributes to biosynthesis of purine ribonucleotide are all EXCEPT:AspartateHistidineGlutamateGlycine  <response>: Ans. b HistidineRef: Harpers 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. 