Catalase activation volume

For blood heparinized venous blood is centrifuged and the upper layer is removed. Wash the erythrocyte sediment three times with 0.9% (w/v) NaCl solution. Haemolyse the washed red cells by adding 4 parts (v/v) of distilled water per volume of packed cells to give a stock haemolysate solution (approx. 5% (w/v)). For assay, dilute the stock solution 1 500 with the phosphate buffer immediately before the assay is to be carried out and determine the haemoglobin content of the solution by the method of Drabkin. The catalase activity is expressed per unit of haemoglobin. 

Figure SJ Activity of the various states of the [NiFe] hydrogenase from A. vinosum as determined with a Pt electrode at 30°C.The reaction was performed in SOmM Tris/HCI (pH 8.0) in a volume of 2 ml. Oxygen was scavenged by adding glucose (90 mM) and glucose oxidase (2.5 mg/ml). Hydrogen peroxide was removed by catalase. When the system was anaerobic, an aliquot of H2-saturated water was added, and a little later enzyme (S-IOnM) was injected. Benzyl viologen (4.2mM) was used as electron acceptor.

By analogy with the mechanism of the catalase reaction, the probable mechanism of the peroxidase reaction is considered (Figure 8.12). Note that a proton transferred to the active site of the biomimetic electrode can be replaced by H+ from the reaction mixture volume. The mechanisms of catalase and peroxidase reactions provide an insight into the ways of their realization in the electrochemical mode. The ratio of products synthesized in both reactions (02 and CH3CHO) depends on the ratio of the H202 and CH3CHO interaction rates with the surface intermediate. 

This material, described by Nakahara and Fukuoka (Nl), is present only in cancer gastric juice. Upon intraperitoneal injection into mice, it depresses the catalase titer of the liver, kidney, and blood. The relationship of this material to mucopolysaccharides and mucoproteins of gastric juice is not well known. Toxohormone— like material obtained from normal stomach which is biologically inactive, however—was found to have lower polarographic activity than that from stomachs with gastric cancer (M18). Separation of materials with toxohormone activity by continuous electrophoresis on paper curtain and column chromatography is discussed in the following review in this volume. 

All tubes contained the following components (in /nmoles unless stated otherwise) potassium phosphate, pH 6.5, 100 ascorbate, 6.0 fumarate, 50 tyramine-/3/3 -3H, 2.0, specific activity 1.15 X 10 CPM//nmole catalase, 300 units, dopamine /3-hydroxylase (4), Final volume, 0.68 ml. at 25°C. Octopamine determined by a minor modification of a published procedure (17). A 0.05 ml. sample of water was obtained by lyophilization and dissolved in 10 ml. of Bray s scintillation mixture. Radioactivity determined in a Packard liquid scintillation spectrometer total counts collected were sufficient to yield a 5% coefficient of variation. The expected tritium release was calculated from the octopamine formed, assuming that the amount of tritium was the same in both /3 positions of the tyramine. The results for the amount of tritium released have been corrected for the amount of exchangeable tritium initially present in the tyramine. 

The new catalase unit was first used by Hennichs (175), working in von Euler s laboratory. He carried out the activity test in 50 ml. of solution, and the Eat.f. has been linked to that volume ever since, so that ... 

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