Harpers

PO5CH 2OHHOHHHOHOHα-D-Ribose 5-phosphate(I)ATP1Mg 2+PAMPPRPPSYNTHASEO5CH 2HO4 1H HH 3 2 O P O POH OHPRPP(II)P OGlutamine GlutamateH 2 O2PPiPRPP GLUTAMYLAMIDOTRANSFERASECH 2OHHOHHHOHGlycine7NH + 3H 2 C 5O C 49 O–P+NH 335-Phospho-β-D-ribosylamine(III)OOH 2CH 2 C 5O7NH + 3C 4NHMg 2 +H HATP ADP + PH HiOH OHGlycinamideribosyl-5-phosphate(IV)N 5 ,N 10 -Methenyl-H 4 folate H 4 folate4FORMYLTRANSFERASEHNH2C578 CH4C 9O NH OR-5- PFormylglycinamideribosyl-5-phosphate(V)Aspartate– OOC+HC NH 3CH 2VI SYNTHETASE5GlnATPMg 2+GluCOO –CHHC– OOCFumarate9– OOCHCH2 C– OOCOCN 6 5C1H3 4H2NCNNCHR-5- PAminoimidazole succinylcarboxamide ribosyl-5-phosphate(IX)H 2 O– OOC8IX SYNTHETASEOC– O 6 543H2NNNCHR-5- PAminoimidazolecarboxylate ribosyl-5-phosphate(VIII)ATP, Mg 2+CO H 2 O Ring closureN2H7HCN6H 72C58 CHCH4C 3 C 9VII CARBOXYLASE H 2 N N VII SYNTHETASEHN NH OR-5- PR-5- PAminoimidazoleFormylglycinamidineribosyl-5-phosphateribosyl-5-phosphate(VII)(VI)ADENYLOSUCCINASEH2 NOCH2NCCNCHNR-5- PN 10 -Formyl-H 4 folate H 4 folate10FORMYLTRANSFERASEOH 2 NCHOCNHCCNCHNR-5- PH 2 O11Ring closureIMP CYCLOHYDROLASEHNHCOCNCCNCHNR-5- PAminoimidazole carboxamideribosyl-5-phosphate(X)Formimidoimidazole carboxamideribosyl-5-phosphate(XI)Inosine monophosphate (IMP)(XII)Figure 34–2. Purine biosynthesis from ribose 5-phosphate and ATP. See text for explanations. (P , PO 3 2– or PO 2 – .)