Question

1.

A) Which of the 20 amino acids must be obtained from dietary sources? Please note for your own knowledge the amino acids that are synthesized via intermediates from glycolysis, the citric acid cycle, and the pentose phosphate shunt.

B) Why is it that multiple biosynthetic reactions leading to amino acids require vitamin B6 = pyridoxal phosphate (PLP)? In other words, enzymes with PLP can do what types of chemistry?

C) The synthesis of the purine ring as part of a nucleotide monophosphate is astounding from the multiple sources accounting for the individual atoms in the two rings. How are the levels of AMP and GMP regulated? And why is this important from the point-of-view of the energetics of the cell?

Answer 1

1.Esential amino acid :-

Tryptophan, Isoleusine , Lysin , Serine , Methionine, Tyrosin , Aspartic acid , Glutamic Acid , Glutamine, Asparagine , Arginin , Alanine , Leucine , Glycine, Cysteine, Phenylalanine, Proline, Valine , Threonine, Histidine.

Glycolysis- serine , cysteine, glycine, alanine

Citric acid cycle :- Glutamine, Glutamic Acid , Arginine, Histidine , Proline , Asparagine , Aspartic Acid , Phenylalanine, Tyrosine, Isoleucine , Valine , Methionine.

Pentose phosphate Shunt :- Phenylalanine, Tyrosine, Tryptophan

2.i. Transamination (PLP as coenzyme)

ii. Decarboxylation (PLP as coenzyme)

iii. Cysteine and Methionine metabolism

iv. Production of niacin from tryptophan.

3.Purine biosynthesis is regulated in branch pathways fron IMP to AMP andGMP , Excess ATP Leads to accelarated synthesis of GMP and excess GTP leads to accelarate synthesis of AMP .