Histidine biosynthesis

1
Histidine biosynthesis
The main precursors are ribose (from PRPP), ATP
and NH3 from GLN.
Imidazole glycerol phosphate is a key
intermediate.
2
Histidine biosynthesis
First, ATP reacts with PRPP
3
Then the purine ring is opened between N1 and C6.
The PRPP-derived ribose opens.
4
Reaction with NH3 (from GLN) gives imidazole
glycerol phosphate and 5-aminoimidazole
4-carboxamide ribonucleotide.
GLN
GLU
Dehydration, transamination and oxidation
reactions convert imidazole glycerol-P to
histidine.
5
The remains of the ATP precursor is an
intermediate in purine nucleotide biosynthesis.
It is recycled.
IMP
AMP
GMP
6
Aromatic AA biosynthesis
Overview
Phosphoenolpyruvate (PEP) erythrose 4-phosphate
Chorismate
Anthranilate
Prephenate
TYR
PHE
TRP