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Human erythrocyte pyruvate kinase was found to be irreversibly inactivated by butanedione in the dark. The second-order rate constants for inactivation at pH 8.0 and 25 degrees C were 2.14 and 2.74 M-1 min-1 in the absence and presence of 50 mM borate, respectively. The pH profile of the inactivation indicated the involvement of a residue with an apparent pK alpha of 8.1-8.3. ADP and phosphoenolpyruvate acted as partial inhibitors of the inactivation process. Certain details of the inactivation, spectral studies, and fluorometric determinations gave evidence for arginine as the only target residue. A total of 23 +/- 3 residues per subunit were modified within the period required for inactivation. In the same period the presence of 4 mM ADP reduced the extent of inactivation by 70% and the number of modified residues to 18 +/- 4. The number of the arginine residues protected by ADP from butanedione modification was 5.0 +/- 1.3 per subunit.

The major glutathione transferases in the rat small-intestine cytosol were isolated and characterized. The enzymes active with 1-chloro-2,4-dinitrobenzene as second substrate were almost quantitatively recovered after affinity chromatography on immobilized S-hexylglutathione. The different basic forms of glutathione transferase, which account for 90% of the activity, were resolved by chromatofocusing. Fractions containing enzymes with lower isoelectric points were not further resolved. The isolated fractions were characterized by their elution position in chromatofocusing, apparent subunit Mr, reactions with specific antibodies, substrate specificities and inhibition characteristics. The major basic forms identified were glutathione transferases 1-1, 4-4 and 7-7. In addition, evidence for the presence of a variant form of subunit 1, as well as trace amounts of subunits 2 and 3, was obtained. A significant amount of transferase 8-8 in the fraction of acidic enzyme forms was demonstrated by immunoblot and Ouchterlony double-diffusion analysis. In the comparison of the occurrence of the different forms of glutathione transferase in liver, lung, kidney and small intestine, it was found that the small intestine is the richest source of glutathione transferase 7-7.

Human plasma cholinesterase was found to be inhibited by 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide in a biphasic manner. The faster phase of the inhibition led to loss of approximately 50% of the activity (measured at pH 7.0, 30 degrees C, using 2.5 mM butyrylthiocholine) and was irreversible. Inhibition in the slower phase was reversible by 0.25 M hydroxylamine. The protective effect of 1 mM propranolol indicated that the target residue in both phases was localized at the active site. Lineweaver-Burk plots for butyrylthiocholine were obtained at different times during the course of inactivation. It was found that for both native and partially inactivated enzymes the plots could be analyzed in terms of two activities showing hyperbolic saturation with the substrate, with Km values of 0.055 +/- 0.015 and 2.0 +/- 0.2 mM. The carbodiimide affected the maximal velocities of the component activities, leaving the Km's unchanged. The low-Km component was lost in the first phase of the inactivation. The loss of the high-Km component paralleled the second phase. It was concluded that the active sites in the tetrameric enzyme form two classes, differing in their affinity for butyrylthiocholine and their susceptibility to inhibition by the active site-directed carbodiimide.

Lymphocyte surface proteins of patients with ataxia-telangiectasia were separated by polyacrylamide gel electrophoresis and compared by autoradiography. The patients lacked one of the two main bands (Band I at the origin). The second main band (Band II) was absent in some cases. All patients had one or two additional bands of smaller molecular weight than Band II except one case who had no band detectable. In the patients, alkaline phosphatase, total ATPase and Mg2+. ATPase were increased but 5'-nucleotidase was normal. The results suggest abnormality in the plasma membranes of the patients' lymphocytes.

The plasma membrane potential of lymphocytes prepared from ataxia telangiectasia (AT) patients and normal subjects was assessed using the optical indicator bis-(3-phenyl-5-oxoisoxazol-4-yl) pentamethineoxonol (oxonol-V). AT lymphocytes had a potential of -46 +/- 9 mV and normal lymphocytes had a potential of -63 +/- 4 mV. The intracellular cation content (Na+ and K+) of AT and normal lymphocytes was similar. AT and normal lymphocytes were both depolarized by extracellular K+ and to a similar extent. This study indicates that one feature characterizing ataxia telangiectasia is a modification of the ability of the lymphocyte cell membrane to sustain a normal membrane potential.

A spectrophotometric method for the determination of arginase (EC 3.5.3.1) is presented. Arginase is coupled to urease and glutamate dehydrogenase and the decrease in absorbance at 340 nm due to the oxidation of NADPH is followed. The method is rapid, is sensitive, is economical and permits continuous monitoring. The initial velocities were directly proportional to the enzyme concentrations between 0.06 and 0.30 units per 0.5 ml. The Lineweaver-Burk plot yielded positive allosteric behavior for the tetrameric enzyme. The K' and the Hill coefficient, n, calculated from Hill plot were found to be 4.7 mM and 1.26 (r = 1.00), respectively. These values are in good agreement with the literature.

The control programs of mosquitoes are physical; chemical, mechanic control, control by sterilization, genetic, public health rules and biological control. Biological control is the most efficient and convenient one because of resistant organisms against insecticides, economic problems and degeneration of the eco-system. This control employs protozoal, fungal, bacterial pathogens, mosquito predator fish, nematoda parasites as bioagents. Safety tests, sensitivity to environmental factors, effectiveness against non-target organisms, production, stability and field trials are all giving promising results.

Human erythrocyte pyruvate kinase (ATP: pyruvate phosphotransferase, E.C.2.7.1.40) is purified 30,000-fold, using a method which includes ammonium sulfate precipitation, Sephadex G-75 filtration, and Blue Dextran-Sepharose 4B chromatography. The enzyme is resolved into two peaks on Blue Dextran-Sepharose 4B. The first peak with sp act of 300 corresponds to the mature form (R4) whereas the second peak with sp act of 180 corresponds to R2R'2. Peaks I and II give one band on 10% polyacrylamide gel without SDS. Peak II gives two bands on 10% SDS gel with molecular weights 60,000 (R') and 57,500 (R). On the other hand, peak I gives only one band on 10% SDS gel having a molecular weight of 57,500. Both the R4 and R2R'2 forms of the enzyme have the same pH optimum of 7.2.