Volume 4, Issue 2
June 1982, pages 127-244
pp 127-132 June 1982
A novel polycationic ionen was synthesized and fractionated on carboxymethyl-Sephadex using a salt gradient in 7M urea. A series of oligomers of discrete length were characterised by ultraviolet spectra. The ultraviolet spectra of oligomers revealed a new band centred at 232.5 nm which was probably due to exciton splitting. Thermal denaturation studies indicated both stabilization of the helix conformation and a higher degree of cooperativity in the melting of DNA (oligomers)n complex as compared to native calf thymus DNA. Ionen oligomers exhibited large extrinsic Cotton effect at 232.5 nm which could be attributed to exciton interaction.
pp 133-138 June 1982
The acidic α-mannosidase was purified 4400-fold by affinity chromatography on Concavalin A-Sepharose and heat treatment at 65‡C in the presence of 1 mM zinc ion. The enzyme did not resolve into multiple forms as in the case of enzymes from human liver and human kidney. The pH optimum of the enzyme was 4.2 in citrate-phosphate buffer. The Km value for p-nitrophenyl-α-D-mannose was 1.9 mM. The molecular weight of the enzyme determined by gel filtration was 300,000. The enzyme contained 10.6% neutral sugars.
pp 139-144 June 1982
The content of DNA, RNA and protein in cerebellum at different stages of the life span of rat as well as the ratios of protein to DNA, showed-that in this region extensive cell proliferation occurs between the 1st and 7th day after birth and once again between the ages of 225 and 750 days. The putative DNA degrading enzymes, acid and alkaline DNases, showed a positive correlation with the rapid DNA accretion noticed during developmental stages as well as during old age. From these results, it could be presumed that there was a second bout of glial cell multiplication in aging cerebellum and that DNases must be playing some important role in the process.
pp 145-152 June 1982
The extractability of chlorogenic acid from defatted sunflower seed flour in water and salt solutions at different pH values and also in aqueous organic solvents was determined. It increased with increase in pH and at pH 8 in water nearly 70% chlorogenic acid was removed in a single extraction, while NaCl did not increase the extraction, and, MgCl2 and CaCl2 increased it, especially at higher concentrations. Methanol, ethanol, isopropanol and acetone, at 20% concentration in water, caused the maximum extraction of polyphenol. These organic solvents without added water were poor solvents for the extraction of polyphenol from the flour.
pp 153-157 June 1982
Β-D-Galactosidase (EC 184.108.40.206) fromLactobacillus bulgaricus (1373) was immobilized in a Polyacrylamide gel lattice in the presence of dithiothreitol, glutathione, cysteine, bovine serum albumin, casein, lactose and glucono-δ-lactone. Cysteine, bovine serum albumin, and lactose were found very effective in preserving the activity. With cysteine, bovine serum albumin and lactose, the activity yields were 61, 60 and 66% respectively, as compared to 31% without protective agents. The yield improved upto 85% when all the three protective agents, cysteine, bovine serum albumin and lactose were added during immobilization. The addition of protective agents did not have any effect on optimum pH, optimum temperature, kinetic constants and pH stability when compared with Β-galactosidase immobilized without the use of protective agents; however the heat and storage stabilities were found to increase.
pp 159-166 June 1982
Studies on the influence of heavy water on mitochondrial respiration and oxidative phosphorylation revealed that both isotope and solvent effects, may be responsible for the observed changes. Although the two types of effects could not be totally delineated from each other by the experimental approaches employed, the isotope effect appeared to be primarily responsible for the uncoupling of oxidative phosphorylation, while the inhibition of respiration in the presence of ADP (State 3 respiration) could be a manifestation of the solvent effect.
pp 167-173 June 1982
Activity of fructose-1,6-bisphosphatase (EC 220.127.116.11), one of the key gluconeogenic enzymes, was measured in human fetal brain and liver during development. Fructose-1,6-bisphosphatase was distributed throughout the different regions of the brain. In contrast to the partially purified enzyme from the brain, the liver enzyme was dependent on Mg2+ for maximal activity, EDTA, citrate, oleate and linoleate were stimulatory, whereas 5′-AMP inhibited the activity of the liver enzyme.
pp 175-182 June 1982
The variation in acid phosphatase (EC 18.104.22.168) activity inAntheraea mylitta was similar in all light and dark groups exposed to different photophases (LD =0:24, 24:0, 18:6, 14:10, 10:14 and 12:12 h) maintaining all along a higher activity than its alkaline counterpart. The highest activity was recorded on day 82 in LD group 10:14 h. The non-diapausingPhilosamia ricini larvae registered highest activity in LD group 0:24 h on day 5. Alkaline phosphatase (EC 22.214.171.124) activity was low all through metamorphosis in both the lepidopterans, although significantly elevated activity was observed on day 5 in larvae of allPhilosamia ricini LD regimens and on day 82 inAntherae mylitta. Photoperiodic effect on Phosphorylase (EC 126.96.36.199) activity, glycogen and inorganic phosphates content have also been studied.
Exposure to LD 10:14, 14:10 and 18:6 h provoked early diapause termination inAntheraea mylitta. The non-diapausingPhilosamia ricini was unaffected in moth emergence but the emerged adults of LD 24:0 and 0:24 h groups were unhealthy, small and did not mate or oviposit.
pp 183-190 June 1982
The addition of the carcinogen, N-methyl N’-nitro N-nitrosoguanidine, to a cell-free system consisting of purified polysome and ‘pH 5 enzyme’ fraction resulted in a marked inhibition of incorporation of (14C)-leucine into polypeptides. The extent of inhibition was remarkably high if the cell-free system contained limiting amount of ‘pH 5 enzyme’ fraction. Under this condition, the rate of inhibition was dependent on the concentration of carcinogen. Some component present in the ‘pH 5 enzyme’ fraction was inferred to be the susceptible factor, since the inhibition at low concentration of carcinogen could be reversed by increasing the amount of this fraction in the polysomal system. It was ascertained that tRNA was the primary target of carcinogenic action. Evidence suggested that functions attributed to tRNA such as aminoacylation and ribosomal transfer were both affected in a characteristic way by the action of the carcinogenic N-nitroso compound.
pp 191-195 June 1982
The kinetic properties of rat liver nuclear lysozyme, earlier purified to homogeneity in our laboratory, have been studied. The enzyme was found to be maximally active in the pH range 4.2 to 5.4 in 0.02 M buffer. Its Km was found to be 333 mg/litre. It was heat sensitive even in the acidic pH range. The enzyme exhibited tissue specific differences when compared with the rat kidney nuclear lysozyme.
pp 197-208 June 1982
The major protein from glanded cottonseed has been isolated in a homogeneous form. Its S20 w value at 1 protein concentration is 6S in 1 M NaCl solution. It contains 1 carbohydrate and is free from phosphorus, gossypol (bound or free) and nucleic acid impurities. It consists of atleast seven non-identical subunits. The protein has an ultraviolet absorption maximum at 278 nm and fluorescence excitation and emission maxima at 280 nm and 325 nm respectively. Optical rotatory dispersion and circular dichroism measurements indicate that the protein consists predominantly of Β-structure and random coil. The observed near-ultraviolet circular dichroic bands can be attributed to tyrosine, phenylalanine and tryptophan residues of the protein.
pp 209-218 June 1982
Conformational energy calculations were carried out on penicillin α-and Β-sulfoxides and δ2- and δ3-cephalosporins, in order to identify the structural features governing their biological activity.
Results on penicillin Β-sulfoxide indicated that in its favoured conformation, the orientation of the aminoacyl group was different from the one required for biological activity. Penicillin α sulfoxide, like penicillin sulfide, favoured two conformations of nearly equal energies, but separated by a much higher energy barrier. The reduced activity of the sulfoxides despite the nonplanarity of their lactam peptide indicated that the orientations of the aminoacyl and carboxyl groups might also govern biological activity.
δ3-cephalosporins favoured two conformations of nearly equal energies, whereas δ2-cephalosporins favoured only one conformation. The lactam peptide was moderately nonplanÄr in the former, but nearly planar in the latter. The differences in the.preferred orientations of the carboxyl group between penicillins and cephalosporins were correlated with the resistance of cephalosporins to penicillinases.
pp 219-225 June 1982
Carboxin prevents the growth of yeast by inhibiting protein synthesis; the resumption of growth in the presence of this chemical appears to be primarily due to a cellular alteration affecting carboxin entry into the cells.
pp 227-237 June 1982
The kinetics of estrogen-induced accumulation of riboflavin-carrier protein in the plasma was investigated in immature male rats using a specific and sensitive homologous radio-immunoassay procedure developed for this purpose. Following a single injection of the steroid hormone, plasma riboflavin-carrier protein levels increased markedly after an initial lag period of approximately 24 h, reaching peak levels around 96 h and declining thereafter. A 1.5 fold amplification of the inductive response was evident on secondary stimulation with the hormone. The magnitude of the response was dependent on hormonal dose, whereas the initial lag phase and the time of peak riboflavin-carrier protein induction were unaltered within the range of the steroid doses (0.1–10 mg/ kg body wt.) tested. Simultaneous administration of progesterone did not affect either the kinetics or the maximum level of the protein induced. The hormonal specificity of this induction was further adduced by the effect of administration of antiestrogens viz., En and Zu chlomiphene citrates, which effectively curtailed hormonal induction of the protein. That the induction involvedde novo-protein synthesis was evident from the complete inhibition obtained upon administration of cycloheximide. Passive immunoneutralization of endogenous riboflavin-carrier protein with antiserum to the homologous protein terminated pregnancy in rats confirming the earlier results with antiserum to chicken riboflavin-carrier protein.
pp 239-244 June 1982
Analysis of ribosomes and the post ribosomal supernatant fraction of actively growing cells ofThermomyces lanuginosus showed the presence of free 5 S RNA in the supernatant fraction. This 5 S RNA was identical to the ribosomal 5 S RNA in its electrophoretic mobility on 10% Polyacrylamide gel and in its base composition. 5 S RNA from both the sources gave evidence for the presence of diphosphate at the 5’ end. Most of the 5 S RNA that appeared in the cytoplasm was that transported from the nucleus during the isolation. This could be prevented by the use of a hexylene glycol-HEPES buffer.
Volume 44 | Issue 5
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