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J Svasti

Publications and source records attributed to J Svasti.

At least 37 records · Page 2Linked to original sources
PubMed1986

Gossypol prevents activation of purified proenzyme of human seminal plasma acidic proteinase.

Gossypol inhibits the potential activity of the proenzyme form of human seminal plasma acidic proteinase, but has no effect on the active enzyme under the conditions tested. Inhibition of proenzyme is rapid and pH-dependent: 50% inhibition can be observed at gossypol concentrations of approx. 1.5 X 10(-5) M. SDS-polyacrylamide gel electrophoresis indicates that treatment of proenzyme with gossypol prevents the formation of active enzyme that normally occurs on acidification. Determination of free amino groups with 1-fluoro-2,4-dinitrobenzene suggests that gossypol reacts with 7.8 out of the 11.0 lysine residues in proenzyme: such a reaction could interfere with the activation process.

Aspartic Acid Endopeptidases↗
PubMed1985

Inhibition of liquefaction and protein degradation in human semen by gossypol.

The liquefaction of freshly ejaculated human semen was delayed by gossypol. Liquefaction is normally accompanied by an autolytic degradation of semen proteins, and prior incubation with gossypol can inhibit factors (presumably proteinases) present in seminal plasma that degrade semen proteins. The possible consequences of this inhibition are discussed in relation to the proposed use of gossypol as a vaginal contraceptive.

Gossypol↗
PubMed1985

Gastricsin in the benign and malignant prostate.

An immunoperoxidase (peroxidase-antiperoxidase) method was used to localise the gastric acid proteinase gastricsin in prostate. The enzyme was present, probably as zymogen, in acinar lining cells in 66 (69%) of 96 cases of benign prostatic enlargement; other normal tissues from male genital tract were negative. It was also present in the tumour cells in 21 (39%) of 54 cases of prostatic adenocarcinoma. The findings support the suggestion that the prostate is the source of the gastricsin of normal seminal fluid. It is not yet clear whether its presence in prostatic carcinomas will be of diagnostic use.

Acid Phosphatase↗
PubMed1984

Effect of vitamin A deficiency on the testis-specific histone TH2B of the rat.

The effect of vitamin A deficiency on rat testis was studied biochemically and histologically. The earliest change in nuclear basic proteins was a decrease and disappearance of the testis-specific protein (TP); the disappearance approximately coincided with cessation of growth. At later stages of deficiency, the testis-specific histone TH2B was markedly reduced and in some cases disappeared, as did the TH1 histone band. Histological studies indicated that the loss of TH2B and TH1 requires a substantial degree of testicular degeneration, because they could still be detected to some extent in testes containing mainly Sertoli cells, reduced numbers of spermatogonia and very few spermatocytes. The effect of retinol in maintaining the germ cells and the testis-specific basic proteins TP and TH2B was very specific, in that it could not be replaced by retinoic acid, which can maintain normal body growth. Prolonged supplementation of vitamin A-deficient animals with retinyl palmitate partially restored the levels of TP, TH2B, and TH1.

Animals↗
PubMed1983

Human testis-specific histone TH2B: fractionation and peptide mapping.

The presence of the nonionic detergent Triton X-100 was shown to improve the resolution of the human TH2B on gel electrophoresis and on gel filtration. Total histones of human testis, including TH2B, were resolved by electrophoresis in 15% polyacrylamide gels containing 0.4% Triton X-100, 1.5 M urea, and 0.9 N acetic acid. Gel filtration on Bio-Gel P-200 in 0.4% Triton X-100, 5.0 M urea, and 0.01 N HCl permitted the purification of human TH2B from human testis and sperm in preparative amounts. The structure of human TH2B so prepared was compared to that of rat TH2B, human H2B, and rat H2B by tryptic peptide mapping. The results showed some similarities between all four proteins, but closer similarity was observed within the germ cell histone (TH2B) group and within the somatic histone (H2B) group than between histones of the same species. In addition, human TH2B and rat TH2B each contained one unique peptide absent from other histones.

Animals↗
PubMed1981

Improved purification and fluorescence changes upon activation of human seminal plasma acidic protease proenzyme.

Modifications have been made to the previous purification procedure so that electrophoretically homogeneous acidic protease (EC 3.4.23.-) proenzyme of specific activity 800 units/mg may be isolated from human seminal plasma with a yield of over 50%. The intrinsic fluorescence of the proenzyme shows maximum excitation and emission wavelengths at 280 and 340 nm, respectively, typical of proteins containing tryptophan. Complete activation causes 30-35% decrease in intrinsic fluorescence, accompanied by a shift in gamma max to the blue of 4-6 nm. Time course studies indicate that acidification of proenzyme to pH 3.1 leads to a sudden large decrease in fluorescence that precedes both the appearance of active enzyme band on sodium dodecyl sulphate (SDS) polyacrylamide gels and the generation of enzyme activity as detected by the turbidimetric milk clotting assay. These results that acidification causes a rapid conformational change which promotes the release of the activation peptide from the proenzyme to yield the active enzyme.

Aspartic Acid Endopeptidases↗
PubMed1980

Effect of ligand binding on the conformation of human plasma vitamin D binding protein (group-specific component).

Several techniques have been used to demonstrate that the binding of specific ligands to human plasma vitamin D binding protein induces a change in protein conformation. Apoprotein and holoprotein show circular dichroism spectra of similar form in the peptide region with double minima at 207 and 218 nm. The minimum mean residue ellipticity of apoprotein (20.6 X 10(3) degrees.cm2.dmol-1) is decreased by about 8% after vitamin D3 binding, suggesting a small change in the backbone conformation. Spectrofluorimetric studies showed that 25-hydroxycholecalciferol causes a saturable enhancement of intrinsic fluorescence of human vitamin D binding protein and alters the pH profile of protein fluorescence, suggesting that there are alterations in the local environment of tryptophan residue(s) after ligand binding. Furthermore, in the presence of 25-hydroxycholecalciferol, the rate of chemical modification of the amino groups in human vitamin D binding protein is decreased and the susceptibility of intact vitamin D binding protein to proteolytic degradation is reduced, suggesting that some surface sites in the vitamin D binding protein molecule are less accessible to external agents. In addition, although the absorbance of vitamin made if difficult to interpret the ultraviolet spectra of holoprotein and apoprotein, the presence of vitamin D binding protein appears to stabilize the vitamin in an aqueous environment, a phenomenon that may be of physiological importance.

Carrier Proteins↗
PubMed1979

Improvement in the resolution of human sperm protamines by use of iodoacetamide as alkylating agent.

By use of the neutral alkylating agent iodo [14C1] acetamide instead of ethylene imine or iodoacetate, the resolution of human protamines on gel electrophoresis and ion-exchange chromatography has been improved. Using 20-cm gels, human protamines may be fractionated into seven bands, including the two chromatographically distinct forms of HP1 and a hitherto undetected component HP4. On ion-exchange chromatography, HP2 and the two forms of HP1 may be isolated in sufficient purity for sequence analysis.

Chromatography, Ion Exchange↗
PubMed1977

An addition at the C-terminus of water-buffalo immunoglobin lambda chains.

The amino acid sequence of the C-terminal tryptic peptide of pooled water-buffalo immunoglobulin lambda chains was determined as Thr-Val-Lys-Pro-Ser-Glu-Cys-Pro-Ser. This sequence is closely homologous to equivalent sequences from other species, but shows an additional amino acid on the C-terminal side of the interchain half-cystine residue.

Amino Acid Sequence↗
PubMed1976

The heterogeneity of the protamines from human spermatozoa.

Nuclear basic protein from ejaculated human spermatozoa were labelled with iodo[14C1]acetic acid and fractionated by ion-exchange chromatography into several pools (named A-K). Gel electrophoresis indicated that the minor protamine components, were present in pool D and that, of the major protamine components, component 1 (pools E, F, G, H) was well separated from the unresolved mixture of component 2 and component 3 (pools I, J, K). Pools G and J were free of other contaminants. Pools D, G, and J produced different radioactive peptides on digestion with trypsin and with thermolysin, and also had quite distinct amino acid compositions. This suggests that the heterogeneity of human protamines is caused by differences in amino acid sequence. Major component 1 also seems to be heterogenous, since it was found in two distinct peaks (pools E and G), but post-translational modification as a cause of the two types of component 1 has not been ruled out. Although all the human protamine components are similar to other mammalian protamines in containing half-cysteine and tyrosine, they also have unique common features such as high histidine and high glutamic acid contents.

Amino Acids↗
PubMed1975

Mouse immunoglobulin subclasses: cyanogen bromide fragments and partial sequence of a gamma1 chain.

The purification and characterisation of all the cyanogen bromide fragments of MOPC 21 heavy (gamma1) chain is described. The ten BrCN fragments account for the whole chain. Four of these fragments have been used to establish the sequence of the C-terminal stretch (138 residues) that includes the entire CH3 and a part of the CH2 homology regions. A comparison of this sequence with homologous sequences is presented. Mouse gamma1 and gamma2 proteins differ much more than the gamma subclasses in humans and in other species. The comparison further suggests that the four human gamma subclasses and mouse gamma1 have a common ancestor which differs from the mouse gamma2 ancestor. Unlike other subclasses, mouse gamma1 and gamma2 genes have diverged before speciation.

Amino Acid Sequence↗