The aerobic oxidation of reduced triphosphopyridine nucleotide by a wheat germ enzyme system.
نویسندگان
چکیده
Demonstration of TPNH Oxidase-The rate of decrease in light absorption at 340 rnp, due to TPNH, was used as an assay for the enzyme. The test was run routinely in glycylglycine buffer of pH 7.4. The conditions are given in detail in the legend to Fig. 1. Under these circumstances, the rate of change in optical density was roughly proportional to the amount of enzyme employed, in the range A log IO/I = -0.010 to -0.200 per 5 minutes. Typical results are shown in Curves 1 and 2 of Fig. 1. Curve 3 demonstrates the inhibition of the oxidation by cyanide, and Curve 4 shows the dependence of the reaction on the presence of oxygen. In this latter experiment, the enzyme and its substrate were incubated for 15 minutes in an evacuated Thunberg tube. During this time no oxidation of TPNH occurred. The reaction mixture was then transferred to a Beckman cuvette, whereupon a slow oxidation ensued, owing to the small amount of 02 dissolved in the liquid during the transfer. After air had been bubbled through the medium for 30 seconds, at 21 minutes, the oxidation rate increased to that observed when the test was run without removal of dissolved 02 by evacuation. In general, the O2 dissolved in
منابع مشابه
Studies on an Enzyme System from Wheat Germ Catalyzing the Aerobic Oxidation of Reduced Triphosphopyridine Nucleotide.
متن کامل
The oxidation of reduced pyridine nucleotides by peroxidase.
A soluble enzyme system which catalyzes the aerobic oxidation of reduced pyridine nucleotides in wheat germ has previously been described (1). Peroxidase was shown to be a component of this system. Later, Humphreys (2) demonstrated that Mn+ and an unidentified cofactor were required for aerobic oxidation of TPNH’ in crude preparations of malic enzyme from wheat germ. Although no attempt was mad...
متن کاملA triphosphopyridine nucleotide dependent alcohol dehydrogenase from Leuconostoc mesenteroides.
Ethanol formation during glucose fermentation is a relatively common activity of microorganisms; a few species, including Leuconostoc mesenterodes, produce ethanol as a major fermentation end product. The significant results from experiments with various species on this subject are: (1) at least three different metabolic pathways are available for anaerobic conversion of glucose to ethanol (Kos...
متن کاملAn Alkaline Phosphatase Lacking Wheat Germ Agglutinin Binding Sites Useful Enzyme for Lectin Assays with Comparable Activity to the Calf Enzyme
Despite the availability of various alkaline phosphatase (ALP) isoenzymes, the calf enzyme is being used in current enzyme assays as the detector enzyme. The glycosylation pattern of this enzyme makes it a suitable ligand for binding to wheat germ agglutinin lectin (WGA). As a result of this property, the enzyme can not be used as a conjugate with this lectin, and the calf enzyme conjugates can...
متن کامل3-Methyleneoxindole reductase of peas.
A 100-fold purification of a reduced triphosphopyridine nucleotide/3-methyleneoxindole reductase of peas has been achieved using conventional protein fractionation procedures. Reduced diphosphopyridine nucleotide is 25-fold less effective than reduced triphosphopyridine nucleotide as the reductant. The preparation is free of other reductase activities including those linking the oxidation of re...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
- The Journal of biological chemistry
دوره 194 1 شماره
صفحات -
تاریخ انتشار 1952