コルチコイド誘導した鶏血漿中F-GOT系アミノ基転移酵素の酵素作用の性質について : I. F-GOT反応における基質濃度と反応速度との関係

DOI Web Site Web Site PubMed

書誌事項

タイトル別名
  • Thermodynamics of Enzymatic Transamination of Corticoid-Induced Aminotransferases of F-GOT System in Fowl Blood Plasma : I. Relationship between Reaction Velocity and Substrate Concentration in F-GOT Reaction
  • コルチコイド ユウドウシタ ニワトリ ケッショウチュウカ GOTケイ アミノキ

この論文をさがす

抄録

Kinetical analysis on the self-control mechanism of corticoid-induced F-GOTgave the following results.Corticoid-induced F-GOT might be one of K class allosteric enzymes and a typical ex-ample of oligomeric enzyme. This enzyme catalyzes the reaction of the forward directionin the presence of L-aspartate and a-ketoglutarate for the following three reasons:(a) F-GOT, particularly homotropic one showing positive cooperativity, shows asigmoid curve in relation to the initial steady-state velocity (Vi) to substrate concentra-tion ([S]), rather than a rectangular hyperbola to be expected from the Michaelis-Mentenrelationship. Apparently, the allosteric transition is also recognized in a cturve of doublereciprocal (Lineweaver-Burk) plot of Vi vs. [S], (b) F-GOT responds to a positive modula-tor with a change in apparent Km(:[84 ;), but without a change in maximum velocity(V=..). This fact proves it to be K enzyme, and (c) Desensitized allosteric F-GOT whichhas lost its previous sensitivity to modulators shows normal Michaelis-Menten kinetics.In this case, a change in V.... in response to the substrate without a change in Michaelisconstant (Km:[5]..), is recognized. This fact proves the catalytic site to be the V form.Such sites are similar to one another. The following consideraiton is put forth: Funda-mentally, F-GOT at a normal steady-state level may exist in a desensitized form ofallosteric F-GOT which has been released by corticoid treatment during the period ofsecondary adaptable responses.Although an excess in substrate resulted in an inhibition of the enzyme activity, thesigmoidal inhibitory curve showed that the kinetic characteristic was not necessarily thesame among enzymes, including an atypical one. It was considered that each enzymemight have been affected differently with its substrate by virtue of its own characteristics.

収録刊行物

キーワード

詳細情報 詳細情報について

問題の指摘

ページトップへ