Regional differentiationnext term in previous termbull sperm plasma membranesnext term

previous termBull spermnext term heads and tails have been separated by proteolytic digestion (trypsin) and previous termplasma membranesnext term have been isolated, using discontinuous sucrose density gradient centrifugation. previous termPlasma membranenext term bound Ca2+-ATPase is shown to be associated mostly with the tail previous termmembranes.next term Pyrene excimer fluorescence and diphenylhexatriene fluorescence polarization experiments indicate a more fluid lipid phase in the tail region. Differences in surface charge distribution have been found, using 1-anilinonaphthalene-8-sulfonate and Tb3+ as fluorescent probes.

Purification of a bacterial organophosphate-hydrolysing phosphatase by cibacron 3GA-Sepharose affinity chromatography

A phosphatase catalysing the hydrolysis of organophosphorus pesticides was purified to homogeneity using Cibacron 3GA-Sepharose CL 6B affinity chromatography. The enzyme which is localized in the periplasm of the bacterium Image NC5 was extracted by treating with 0.2M MgCl2, pH 8.4. The enzyme was adsorbed to the Cibacron-Sepharose at pH 7.0 and eluted with Tris-HCl buffer at pH 8.0, with 47 per cent recovery. The enzyme thus obtained was electrophoretically homogeneous. This simple affinity purification procedure enhances the potential for its use in large scale detoxification systems.

Synthetic peptides as chemoattractants for bull spermatozoa structure activity correlations

The ability of various synthetic peptide analogs of. Formyl-Met-Leu-Phe to induce chemotaxis in bull sperm is compared using an inverted capillary assay. The formyl group is essential for chemotactic activity and corresponding t-butyloxycarbonyl tripeptides are inactive. Sequence analogs, Formyl-Met-Phe-Leu, Formyl-Leu-Met-Phe and Formyl-Leu-Phe-Met are active. Replacement of Met and Leu by Pro does not diminish activity. Formyl-Met-Leu-Phe-NH2 is active suggesting that electrostatic interactions involving the carboxyl group may be unimportant in receptor interactions. The studies establish the importance of an amino terminal formyl group and a sequence of at least three hydrophobic residues, for inducing sperm chemotaxis.

Biosynthesis of cytoplasmic subunits of cytochrome C oxidase in rat liver

The biosynthesis of the cytoplasmic subunits of cytochrome oxidase from rat liver has been studied in vitro by translating liver poly (A)-containing RNA in the wheat germ cell-free system and immunoprecipitating the products with anti-cytochrome oxidase antibody. Analysis of the labelled immunoprecipitate on SDS-gels does not reveal the presence of a polyprotein precursor. On the other hand discrete products which are either slightly bigger or closely similar to the mature subunits present in purified cytochrome oxidase have been detected.

A delphi study on health in future India

PIP: A delphi study was conducted to identify or envision health scenarios in India by the year 2000. Questionnaires consisting of 48 questions on 5 areas (diagnosis and therapy; family planning; pharmaceuticals and drugs; biochemical and biomedical research; health services) were mailed to 250 experts in India. 36 responded. Results were compiled and mailed back to the respondents for changes and comments. 17 people responded. Results of the delphi study shows that policy decisions with respect to compulsory family planning as well as health education at secondary school level will precede further breakthroughs in birth control technology. Non operation reversible sterilization procedures, immunological birth control, Ayurvedic medicines for contraception and abortion, and selection of baby's sex are all possible by 2000 thereafter. Complete eradication of infectious diseases, malnutrition and associated diseases is considered unlikely before 2000, as are advances in biomedical research. Changes in health services (e.g., significant increases in hospital beds and doctors, cheap bulk drugs), particularly in rural areas, are imminent, leading to prolonging of life expectancy to 70 years. Genetic engineering may provide significant breakthroughs in the prevention of malignancies and cardiac disorders. The India delphi study is patterned after a similar delphi study conducted in the U.S. by Smith, Kline and French (SKF) Laboratories in 1968. The SKF study was able to predict some breakthroughs with basic research which have been realized.

A novel Z-structure for poly d(GC).poly d(GC)

A novel zig-zag (Z) structure is proposed for poly d(GC).poly d(GC). The proposed model closely resembles the crystal structure of d(CG)3.

Helical conformations of three crystalline pentapeptide fragments of suzukacillin, a membrane channel forming polypeptide

The crystal structures of three pentapeptide fragments of suzukacillin-A have been determined. Boc-Aib-Pro-Val-Aib-Val-OMe (peptide 1–5) adopts a distorted helical conformation, stabilized by three intramolecular hydrogen bonds (two 5→1, one 4→1). Boc-Ala-Aib-Ala-Aib-Aib-OMe (peptide 6–10) and Boc-Leu-Aib-Pro-Val-Aib-OMe (peptide 16–20) adopt 310 helical structures stabilized by three and two 4→1 intramolecular hydrogen bonds, respectively. These structures provide substantial support for a largely helical conformation for the suzukacillin membrane channel.

Microsomal 11-Alpha-hydroxylation of progesterone in Aspergillius ochraceus: Part I: Characterization of the hydroxylase system

Microsomes (105,000xg sediment) prepared from induced cells of A.ochraceus was found to hydroxylate progesterone to 11-Alpha-hydroxyprogesterone (11a-OHP) in high yields (85-�90% in 30 min.) in the presence of NADPH and O2. The pH optimum for the hydroxylase was found to be 7.7. However, for the isolation of active microsomes grinding of the mycelium should be carried out at pH 8.3. Metyrapone, carbon monoxide, SKF-525A, p-CMB and N-methyl maleimide inhibited the hydroxylase activity indicating the involvement of cytochrome P-450 system. The inhibition of the hydroxylase by cytochrome Image and the presence of high levels of NADPH-cytochrome Image reductase in induced microsomes suggest that the reductase could be one of the components in the hydroxylase system.

Interaction of manganese(II) with valinomycin: Observation of mixed complexes

The interaction of antibiotic valinomycin with manganese (II) has been studied using circular dichroism, electron spin resonance and infrared techniques. Results show that Mn(II) forms complexes with valinomycin in both 2:1 (valinomycin-ion-valinomycin sandwich) and 1:1 (equimolar) stoichiometries. The 1:1 type observed here is very different from the well known K+-valinomycin bracelet conformation.

A 13C-NMR study of non-planar distortions in amides

The technique of 13C-NMR spectroscopy of oriented systems to problems of biological importance has been suggested and used to investigate non-planar distortions in substituted amides—models for peptides. The studies in conjunction with the proton magnetic resonance data on 5N-[13C]methyl[13C]formamide oriented in a nematic solvent provide all the direct dipolar couplings between the interacting nuclei in the system. When the 13C- and the 1H-NMR experiments are performed under non-identical conditions, 22 different direct dipolar couplings are obtained. It is demostrated that they can be used to determine unambiguously non-planar distortions around the nitrogen atom together with other geometrical data and the molecular order.

A hexokinase effect in the inhibition of oxidative phosphorylation in heart muscle mitochondria by Adriamycin

The inhibitory action of the anticancer antibiotic, Adriamycin, on succinate-dependent oxidative phosphorylation in heart mitochondria was markedly potentiated by the presence of hexokinase in the reaction medium. This 'hexokinase effect' was not observed in the oxidation of NAD+-linked substrates, or when liver or kidney mitochondria were used in place of heart mitochondria. These results offer a biochemical explanation for the extreme cardiac toxicity of the drug.

Effect of deprivation of vitamin A on the basic proteins of the nuclei of rat testes

The relative concentrations of the major histones, namely, H1, TH1, H2A, H2B, H3 and H4 are not significantly changed in the testes of the vitamin A-deficient rats, as compared to those in the normal controls. But the testis-specific protein, TP, which is synthesized at the mid-spermatid stage, is markedly reduced in the testes of the deficient rats. On supplementation of the deficient rats with retinyl acetate for 28 days, there was a 50% recovery in the relative concentration of the TP with respect to the total amounts of H1 and TH1.

Omega-hydroxylation of acyclic monoterpene alcohols by rat lung microsomes

Rat lung microsomes were shown to ω-hydroxylate acyclic monoterpene alcohols in the presence of NADPH and O2. NADH could neither support hydroxylation efficiently nor did it show synergistic effect. The hydroxylase activity was greater in microsomes prepared from β-naphthoflavone (BNF)-treated rats than from phenobarbital (PB)-treated or control microsomal preparations. Hydroxylation was specific to the C-8 position in geraniol and has a pH optimum of 7.8. The inhibition of the hydroxylase activity by SKF-525A, CO, N-ethylmaleimide, ellipticine, α-naphthoflavone, cyt. Image and p-CMB indicated the involvement of the cyt. P-450 system. However, NaN3 stimulated the hydroxylase activity to a significant level. Rat kidney microsomes were also capable of ω-hydroxylating geraniol although the activity was lower than that observed with lungs.

Regional differentiation in bull sperm plasma-membranes

Bull sperm heads and tails have been separated by proteolytic digestion (trypsin) and plasma membranes have been isolated, using discontinuous sucrose density gradient centrifugation. Plasma membrane bound Ca2+-ATPase is shown to be associated mostly with the tail membranes. Pyrene excimer fluorescence and diphenylhexatriene fluorescence polarization experiments indicate a more fluid lipid phase in the tail region. Differences in surface charge distribution have been found, using 1-anilinonaphthalene-8-sulfonate and Tb3+ as fluorescent probes.

Adriamycin affects plasma membrane redox functions

Adriamycin (Doxorubicin) stimulates NADH oxidase activity in liver plasma membrane, but does not cause NADH oxidase activity to appear where it is not initially present, as in erythrocyte membrane. NADH dehydrogenase from rat liver and erythrocyte plasma membranes shows similar adriamycin effects with other electron acceptors. Both NADH ferricyanide reductase and vanadate-stimulated NADH oxidation are inhibited by adriamycin, as is a cyanide insensitive ascorbate oxidase activity, whereas NADH cytochrome c reductase is not affected. The effects may contribute to the growth inhibitory (control) and/or deleterious effects of adriamycin. It is clear that adriamycin effects on the plasma membrane dehydrogenase involve more than a simple catalysis of superoxide formation.