In step 2 of the citric acid cycle (Figure), cis-aconitate reacts with water to give (2R, 3S)-isocitrate. Does ?OH add from the Re face of the double bond or from the Si face? What about ?H? Does the addition of water occur with syn or anti geometry?

Transcribed Image Text:

O Acetyl CoA adds to H3C SCOA oxaloacetate in an aldol Acetyl CoA reaction to give citrate. HSCOA HO co, .co co2 Oxaloacetate Citrate O Citrate is isomerized by dehydration and rehydration to give isocitrate. O Oxidation of (St-malate gives oxaloacotate, completing the cycie. NADHVH NAD н сот но "O,C. co, "0,C. Co H OH (S)-Malate (L-malate) Isocitrate O Fumarate undergoes conjugate addition of water to its double bond to give (S-malate. NAD* O lsocitrate undorgoes oxidation and decarboxylation to give a-kotoglutarato. NADHH H20 + co2 H. co, "O2C. co, a-Ketoglutarate Fumarate HSCOA Oa-Ketoglutarate is decar- boxylated, oxidized, and converted into the thioester + NAD O Succinate is dehydro genated by FAD to give fumarate. FADH2 NADHVH + Co2 FAD succinyl CoA. CO HSCOA .co, COAS, Succinate GTP GDP Succinyl CoA 6 Succinyl CoA is converted to succinate in a reaction coupled to the phosphorylation of GDP to give GTP. H20 co, "02C. "02C. .co, H OH Н cis-Aconitate (2R,3S)-Isocitrate