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흰쥐 간 원형질막 5'-Nucleotidase의 시험관내 활성증가 기전 : Mechanism for Increase in 5'-Nucleotidase Activity of Rat Liver Plasma Membrane npon Aging in vitro
DC Field | Value | Language |
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dc.contributor.author | 정홍근 | - |
dc.contributor.author | 이기영 | - |
dc.date.accessioned | 2009-08-09T14:01:15Z | - |
dc.date.available | 2009-08-09T14:01:15Z | - |
dc.date.issued | 1980-03 | - |
dc.identifier.citation | Seoul J Med, Vol.21 No.1, pp. 1-13 | - |
dc.identifier.issn | 0582-6802 | - |
dc.identifier.uri | https://hdl.handle.net/10371/6646 | - |
dc.description.abstract | 5'-Nucleotidase is one of the marker enzymes for plasma
membrane in subcellular fractionation. In recent years it ia sbown that the enzyme is not only important in its diagnostic value for hepatic meta' static carcillOma. but also responsible for its regulation of blood Sow through hydrolysis of AMP to adenosine. a powerful vasodilator. It was reported as well that its activity of plasma membrane is increased upon aging the membrane. While most enzymes bound to membranes decrease in their activities upon aging the membranes in vitro, 5'nucleotidase activity is increased to the contrary under the same condition. The present investigation was carried out to elucidate the possible mechanism involved in the phenomenon. Plasma membrane was purified from rat liver homogenate by sucrose density gradient and was suspended in isotonic sucrose solution. part of which was sonified and ultracentrifuged to obtain membrane- free supernatant, and both samples were used as enzyme sources. The behaviors of 5'-nucleotidase were observed in the control system consisting of substrate and buffer. and in the activation system consisting of substrate, buffer, sodium deoxycholate, and MnCI•. The results obtained are summarized as follows. 1. From the results showing the increased activities of 5' -nucleotidase of both the plasma membrane suspension and the membrane-free supernatant upon aging the samples, it is concluded that it is independent of the membrane structure but is due to the property of enzyme molecule itself. The 5'nucleotidase activities of both the suspension and the supernatant, measured in the activation system were approximately 100% and 70% respectively higher than those measured in the control system. After incubation of the suspension at 45°C for 1 hour. the 5' -nucleotidase activity was increased by 16% in the control system, while it showed no variation in the activation system. 2. The increase in 5'-nucletidase activity caused with deoxycholate in the absence of Mn* in the assay system was a very slow reaction but the reaction reached immediately to a maximum in the presence of Mn*. 3. Apparent Km values for 5' -riucleotidase measured with the same amount of suspension In the control system and in the activation system were the same, O. 12mM but Vmax for the reaction was about 2-fold greater in the activation system than that measured in the control system. 4. The increase in 5'-nucleotidase activities of the supension and the supernatant was directly dependent on the concentration of deoxycholate in the presence of Mn* in the assay system, while their rates of increase upon aging the enzyme preparation were inversely dependent on the concentration of deoxycholate. 5. The above results may well be explained reasonably by assuming the presence of a regulatory substance. R being associated with the catalytic enzyme molecule, C of 5'-nucleotidase; C, an active form of the enzyme, whereas C.R, a latent form of the enzyme. From the foregoing results it can be inferred that C could be a thermally stable protein, whereas R may be a thermally unstable substance; the latter being slowly denatured upon aging and released from C' R, which leads eventually to the increase in active form. It can also be inferred that R is released from C·R by deoxycholate in the activation system for which the following equdtion could be suggested, Mn* C·R+D=C+R·D(D, the molecule of deoxycholate) | - |
dc.language.iso | ko | - |
dc.publisher | 서울대학교 의과대학 | - |
dc.title | 흰쥐 간 원형질막 5'-Nucleotidase의 시험관내 활성증가 기전 | - |
dc.title.alternative | Mechanism for Increase in 5'-Nucleotidase Activity of Rat Liver Plasma Membrane npon Aging in vitro | - |
dc.type | SNU Journal | - |
dc.contributor.AlternativeAuthor | Chung, Hong Keun | - |
dc.contributor.AlternativeAuthor | Lee, Ki Yung | - |
dc.citation.journaltitle | 서울 의대 잡지 | - |
dc.citation.journaltitle | 서울 의대 학술지 | - |
dc.citation.journaltitle | Seoul Journal of Medicine | - |
dc.citation.endpage | 13 | - |
dc.citation.number | 1 | - |
dc.citation.pages | 1-13 | - |
dc.citation.startpage | 1 | - |
dc.citation.volume | 21 | - |
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