Biosynthesis of Pyridoxal Phosphate Oxidation of thioester-OH group at C2 by NAD+gives 3- hydroxy-4-phosphohydroxy-2-ketobutyrate NAD+ Enz Enz CONH2 -H NADH/H+ H20 En2SH OH OH H OH -OH H -OH OH CH20P032 CH20P032 CH20P032 D-Erythrose Hemithioacetal Thioester 4-phosphate 0c0 NAD+ NADH/H+ H OH C=0 H -OH H -OH CH20P032 CH2OPO32- D-Erythronate 3-Hydroxy-4-phospho- 4-phosphate hydroxy-2-ketobutyrate▪ Oxidation of thioester –OH group at C2 by NAD+ gives 3- hydroxy-4-phosphohydroxy-2-ketobutyrate Biosynthesis of Pyridoxal Phosphate