OCR Text |
Show W Enzyme; New 'Pathway5! occurring with the Krebs cycle." Dr. Plaut kn received an annual grant for his research project since 1952, at first from the National Headt Institute, Insti-tute, and presently from the National Institute of Arthritis and Metabolic Diseases. The grant was recently renewed for another five-year period. The project, titled Pathways and Compounds of Intermediary Metabolism," covers a great many other projects, according to Dr. Plaut, of which the research re-search concerned with DPN is-ocitrate is-ocitrate hehydrobenase is just one. IN ORDER to demonstrate the suspected key role of the enzyme en-zyme in the Krebs cycle oxidation oxida-tion the investigators wanted to learn if it is active enough to account ac-count for the over-all oxidation process. The activity of the enzyme en-zyme seemed to be low, .explained .explain-ed Dr. Plaut; in fact, too low, to account totally for the over-all process. "When we looked into the mechanism of action of the enzyme, en-zyme, the reason for its apparent appar-ent low activity was discovered," he said. "Previous research had missed an additional co-factor which enhances the activity markedly. This co-factor is adenosine aden-osine diphosphate, or ADP. The enhancement of activity by ADP of isocitrate dehydrogenase is enough to account for its participation parti-cipation in the over-all oxidation r 1 tit SUM '! , ctaff Writer A factor & re inn)8"4 f.L major kffoodituffs to S including $l La today by m Sr W. E. Medicines Metabolic Dis-x Dis-x y'Z meeting of trie TO Dr. Plaut. lSU are turned ;pch can take the ;JrprocesS by which ; led into useful en- i are involved. iXorcitncacidcycle 's which acte on the li other metabolic re-'dW re-'dW a major portion ts'' jfctirffe. This en- 0PN-linked envyme, isocitrate dehydrogenase, in the metabolic process, heart muscle was examined ex-amined specilically the mitra-chrondria mitra-chrondria of these cells. Mitro-chrondria Mitro-chrondria are small particles within each cell. They are the "powerhouse" or structures of the cell that provide it with energy en-ergy Mitochandria actually the structures of the cell that provide pro-vide it with energy. Mitochondria actually contain the oxidative machinery of the Krebs cycle. In their research, Dr. Plaut explained that he and his colleagues col-leagues found that TPN-linked enzyme exists principally in that part of the cell not concerned con-cerned in the Krebs cycle, while the DPN-linked enzyme is found exclusively in the mitochondria. mi-tochondria. "It would be desirable that the enzymes be in the same part of the cell where the oxidation process takes place," explained Dr. Plaut. "Therefore, it would seem that the DPN-linked enzyme, en-zyme, isocitrate dehydrogenase, is the enzyme concerned with this oxidation process rather than the TPN-linked enzyme," he said. ffl ilVj2elforPrimarytyi?s, ."ictivities such as: (I) all kinds; (2) synthesis s- Ib compounds from m to form starches, rains and nucleic acids; cjort of materials; and I r;i conduction and im- f incurrence of the Krebs requires the presence of i (ozymes and coen- W t fa) DPN, according to fetal. Krebs cycle is present in s ol practically all tis-U tis-U ( the body. It involves the Mfdown of such majoi n j & as fatty acids, carbo-,m carbo-,m s, and amino acids to dioxide and water. The sf-ta involves many steps, A step is dependent on jH , race of its appropriate fej KEY STEP in the cycle ry ( nidation of isocitrate via Is syne isocitrate dehydro-tE dehydro-tE t" explained Dr. Plaut. ok Edition results in the re-k re-k i energy. Dr. Plaut said i enzymes are known to ' J it this process; one re 'ie presence of the coen- iphosphopyridine nucleo-V,and nucleo-V,and the other' dip j nucleotide, or ' ; is the smaller, non- 3 part of an enzyme). sent research conducted me ('Pint and his colleagues i(j:K3nine the role of the MS |