Biochemical changes in some acrosomal enzymes of spermatozoa during maturation

Goat spermatozoal hyaluronidase and acrosin show significantly increased activities during transition from caput to cauda epididymis. The activity of alkaline phosphatase decreases during spermatozoal transport through epididymis.

Aminopeptidase in human seminal plasma

Aminopeptidase of seminal plasma was studied in normozoospermic, oligozoospermic, obstructive and non-obstructive azoospermic men. Significantly higher activity was observed in non-obstructive azoospermic patients than that of other three groups. L-Alanine beta-naphthylamide hydrochloride was found to have highest hydrolysis rate in comparison to various other aminoacyl beta-naphthylamide hydrochlorides which were used for determining substrate specificity. 50% inhibitions of the enzyme activity by EDTA and 1,10-phenanthroline were obtained at 5.77 X 10(-3) M and 3.13 X 10(-6) M concentrations respectively. A single band for aminopeptidase in the activity - gel electrophoresis was obtained for all the categories of seminal plasma and the enzyme exhibited the characteristics of metalloprotein.

Enzymic activities in the seminal plasma of normospermic, oligospermic and infertile azoospermic men

Activities of seminal plasma alpha-D-glucosidase, beta-D-galactosidase, alpha-amylase, chymotrypsin-like enzyme and RNAase were studied in normo spermic, oligospermic and non-obstructive azoospermic men. No significant change in the activities of the aforesaid enzymes were found amongst the three catagories, classified according to sperm density.

Correlation between rate constant for reduction and redox potential as a basis for systematic investigation of reaction mechanisms of electron transfer proteins

Rate constants for the reduction of approximately 40 electron transfer proteins by photoreduced flavins have been determined by laser flash photolysis techniques. The data for a series of 12 homologous cytochromes and 10 homologous high redox potential ferredoxins (HiPIPs) are in excellent agreement with semi-empirical equations relating rate constant and thermodynamic redox potential that have proven applicable to nonbiological electron transfer systems. These correlations allow the establishment of relative reactivities within structurally homologous classes of biological oxidation-reduction proteins, including cytochromes and HiPIPs, and a variety of nonhomologous heme-, iron-sulfur-, copper-, and flavin-containing proteins. A qualitative correspondence is shown to exist between such relative reactivity and the extent of solvent exposure of the redox centers in a particular structural class. The implications of these results are considered, and it is concluded that free energy relationships provide a sound basis for systematic analysis of reaction mechanisms of electron transfer proteins.

Lysis of nitrofurantoin-resistant strain of Vibrio el tor

Both nitrofurantoin-sensitive and nitrofurantoin-resistant strains of Vibrio el tor were found to lyze in the presence of Tris-EDTA at alkaline pH. The rate of lysis was appreciably enhanced by lysozyme. The amounts of intracellular components, viz. proteins and carbohydrates, released from the nitrofurantoin-sensitive strain by Tris-EDTA treatment, were significantly lower than those from the nitrofurantoin-resistant strain. Differences in periplasmic proteins released from Tris-EDTA treated cells of nitrofurantoin-resistant and -sensitive strains were revealed by gel electrophoresis.

Effect of dieldrin on rat liver plasma membrane enzymes

Dieldrin, an organochlorine insecticide, when administered orally to male albino rats at a dose of 5 mg/kg body weight/day for 15 days inhibits the enzyme Mg2+ -ATPase and stimulates the activity of 5'-nucleotidase and NADH-dehydrogenase in liver plasma membrane. L-ascorbic acid supplementation offers some protection in relation to the inhibition of Mg2+ -ATPase.

Studies on L-ascorbic acid metabolism in rats under chronic toxicity due to organophosphorus insecticides: effects of supplementation of L-ascorbic acid in high doses

The effects of chronic administration of two organophosphorus insecticides, parathion and malathion on the growth rate, ascorbic acid metabolism and some other nutritional and physiological parameters in rats were studied. Both parathion and malathion toxicity retarded the growth rate of rats. Inhibition of brain acetylcholinesterase was taken as an index of organophosphorus insecticide toxicity. Haemoglobin concentration of blood and organ weights were not affected under the toxic conditions. Parathion and malathion administration stimulated the activity of L-gulonolactone oxidase along with a simultaneous increase in the tissue storage and urinary excretion of vitamin C. The activities of other enzymes of ascorbic acid metabolism, dehydroascorbatase, uronolactonase, and L-gulonate dehydrogenase and decarboxylase were altered under the experimental conditions. Only minor histological changes of the liver and kidney tissues were noted under parathion and malathion toxicities. Excess intake of vitamin C under the toxic conditions was found to be very effective in counteracting the growth retardation and also the alterations produced by parathion and malathion both at the enzymatic and histological levels.

Modification of Drill Point for Reducing Thrust

A considerable amount of thrust force during drilling is due to the cutting action at the chisel edge of drills. This is in turn due to large values of negative rake angle along with a very small cutting velocity in the zone of chisel edge. The authors have developed a grinding technique for modifying the chisel edge into a pair of auxiliary cutting edges with positive rake angle by generating two slots at the chisel point in a manner similar to Zhirov-point drills. Analytical expressions have been developed for analyzing the geometry of modified chisel edge. Experimental investigations have indicated that during drilling of cast iron such modifications result in the reduction of thrust force by about 50 percent. However, there is an optimum orientation angle and setting angle which should be chosen during grinding of drills in order to get the maximum benefit in regards to the reduction of thrust force.