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(一)本報告提供了一個從輔酶Ⅰ,用酶還原法製備還原輔酶Ⅰ的方法。我們所製得的還原輔酶Ⅰ鈉鹽乾粉,可以在低温保存數月而不被氧化。 (二)與心肌製劑中顆粒相結合的輔酶Ⅰ細胞色素還原酶系,和用乙醇抽出的水溶性的輔酶Ⅰ細胞色素還原酶的性質頗不相同。其中比較重要的不同點是對於細胞色素c的親力,前者遠大於後者,其米氏常數僅約為後者的十二分之一。 (三)用一心肌顆粒製劑作為材料,無論用氧或過量之細胞色素c作為氫受體,還原輔酶Ⅰ與琥珀酸同時氧化時的總速度,不等於二者分別氧化時速度之和,而僅等於其中氧化較快者單獨氧化時之速度。但如用[2,6]二氯靛酚作為氫受體時,二者共同氧化時之總速度完全等於二者分別氧化時速度的和。 (四)當用氧或過量之細胞色素c作為氫受體時,琥珀酸與還原輔酶Ⅰ能彼此互相抑制對方氧化的速度。有足夠的實驗材料說明,還原輔酶Ⅰ對於琥珀酸氧化的抑制,不是由於草醯乙酸聚集的緣故。 (五)如果在反應混合物中同時含有琥珀酸脫氫酶的專一抑制劑,丙二酸,則琥珀酸對於還原輔酶Ⅰ氧化作用的抑制即被解除。 (六)根據以上的實驗結果,可以認為,還原輔酶Ⅰ及琥珀酸先通過一個共同的因子與細胞色素c作用。這個共同的因子在一般情形之下,也是這兩個酶系統的速度限制因子。應該指出在我們的實驗中,並未使用任何可能影響酶系統結構的條件,因此我們的結果是在一個比較接近於生理狀態的情形之下獲得的。 (七)應該着重指出,從本報告的結果可以看到,一個用人為的方法從複雜酶系上溶解下來的酶的性質,有時並不能代表這個酶在有組織的酶系統中的真實情况。 (八)我們相信,本報告所說明的兩酶系競爭一個共同因子的一些現象,將为研究複雜酶系之間的相互關係,提供一個新的方法。
(A) The present report provides a method for the preparation of reduced coenzyme I from Coenzyme I by enzymatic reduction. We prepared the reduction of coenzyme Ⅰ sodium salt powder, can be stored at low temperatures for several months without being oxidized. (II) Coenzyme I cytochrome reductase system that binds to particles in a myocardial preparation, and water-soluble coenzyme I cytochrome reductase extracted from ethanol have quite different properties. One of the more important difference is the affinity for cytochrome c, the former is much larger than the latter, the Michaelis constant is only about one-twelfth of the latter. (C) with a myocardial particle preparation as a material, regardless of the use of oxygen or excess of cytochrome c as a hydrogen acceptor, coenzyme Ⅰ and succinic acid oxidation while the total speed, not equal to the speed of the two when the sum of oxidation, and Only equal to the faster oxidation of the oxidation rate alone. However, if [2,6] dichlorophenolindophenol is used as a hydrogen acceptor, the total rate of co-oxidation between the two is exactly the sum of the rates of oxidation of the two. (D) When using oxygen or excess cytochrome c as a hydrogen acceptor, succinic acid and reduced coenzyme I can mutually inhibit each other’s oxidation rate. Sufficient experimental material indicates that the inhibition of succinate oxidation by the reduced coenzyme I is not due to the aggregation of the caulis acetic acid. (E) Suppression of succinate oxidation by reduced coenzyme I is relieved if both the malonate and succinate are included in the reaction mixture as a specific inhibitor of succinate dehydrogenase. (Vi) Based on the above experimental results, it can be considered that the reduction of coenzyme I and succinic acid through a common factor and cytochrome c role. This common factor, in the general case, is also the rate limiting factor for both enzyme systems. It should be noted that in our experiments, we did not use any conditions that could affect the structure of the enzyme system, so our results were obtained in a more physiological condition. (VII) It should be emphasized that from the results of this report, it can be seen that the nature of an enzyme that is artificially solubilized from complex enzyme systems sometimes does not represent the true state of the enzyme in the organized enzyme system . (8) We believe that some of the phenomena that the two enzymes compete for a common factor described in this report will provide a new method for studying the interrelationships among complex enzyme systems.