北大生化ppt課件-資料下載頁
2025-05-06 12:18本頁面
【正文】 athway converts glucose to specialized products needed by cell biosynthesis: NADPH and Ribose 5phosphate This is primarily an anabolic pathway. To counter the damaging effects of oxygen radicals For Reductive biosynthesis Some biological roles served by PPP Nucleotide biosynthesis PPP in rapidly dividing cells Glucose Glycogen Cyclic ester The Nonoxidative phase of PPP Isomerization amp。 epimerization of Ru5P Carboncarbon bond cleavage and formation TPP TPP 轉(zhuǎn)羥乙醛酶 轉(zhuǎn)二羥丙酮基酶 Ribulose 1,5bisphophate is regenerated also via this pathway in the Calvin cycle. Glycolysis Two other ways of displaying the PPP TPP is involved in the CC cleavage and formation reaction catalyzed by transketolase: transferring two carbons from a ketose to an aldose. Transaldolase catalyzes a reaction in which a threecarbon unit is transferred from a ketose to an aldose without being helped by any cofactor. G6P is partitioned between glycolysis and PPP Summary (1) ? Dglucose is a monly used fuel and versatile precursor in almost all anisms. ? The study of glucose degradation has a rich history in biochemistry (especially for enzymology). ? Glucose is first converted into two threecarbon pyruvates via the tenstep glycolysis pathway without directly consuming O2 and with a production of two ATP molecules by substratelevel phosphorylation. ? Limited amount of energy can be released by oxidizing glucose under anaerobic conditions by fermentation. ? The enzymes participating glycolysis may form multiple enzyme plexes, where substrate is channeled from one enzyme to another. ? The sugar units on glycogen is converted to glucose 1phosphate via phosphorolysis, which is catalyzed by glycogen phosphorylase. ? Glucose 6phosphate can also be oxidized to form ribose 5phosphate and NADPH via the pentose phosphate pathway. Summary (2)
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