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Biomedical subjects

S Ray

Publications and source records attributed to S Ray.

At least 307 records · Page 17Linked to original sources
PubMed1985

L-Threonine dehydrogenase from goat liver. Feedback inhibition by methylglyoxal.

L-Threonine dehydrogenase, which forms aminoacetone from L-threonine and NAD, has been extensively purified from goat liver. A feedback inhibition of this enzyme has been observed with methylglyoxal. Kinetic data and other experiments indicate that methylglyoxal acts at a site other than the active site of the enzyme. The enzyme contains a single subunit of Mr 89,000. The apparent Km values of the enzyme for L-threonine and NAD were found to be 5.5 and 1 mM, respectively.

Alcohol Oxidoreductases↗
PubMed1984

Cis isomer of centchroman--a selective ligand for the microsomal antiestrogen binding site.

Several compounds structurally related to the triarylethylene antiestrogens, but possessing weak estrogen receptor affinities, were assessed for their ability to interact with the microsomal antiestrogen binding site. While all the compounds tested did interact with this site their relative affinities were somewhat lower than that of tamoxifen. One of these, viz., the cis isomer of centchroman, has however emerged as a selective ligand for the antiestrogen binding site since its estrogen receptor affinity is nearly 50,000 times lower on a relative scale.

Animals↗
PubMed1984

Purification and partial characterization of a methylglyoxal reductase from goat liver.

An enzyme which catalyzes the reduction of methylglyoxal to lactaldehyde has been isolated and purified from goat liver to apparent homogeneity. NADH was found to be a better substrate than NADPH for methylglyoxal reduction. Stoichiometrically equivalent amounts of lactaldehyde and NAD are formed from methylglyoxal and NADH. Enzyme activity was located only in the soluble supernatant fractions of liver cells. Of the various carbonyl compounds tested, methylglyoxal was found to be the best substrate. The pH optimum of the enzyme was found to be 6.5, and Km for methylglyoxal was 0.4 mM. The molecular weight of the enzyme was found to be 89000 by gel filtration on a Sephadex G-200 column. Electrophoresis on sodium dodecyl sulfate-polyacrylamide gel revealed that the enzyme is composed of two subunits. The enzyme is highly sensitive to sulfhydryl group reagents. The inactivation by p-chloromercuribenzoate could be substantially protected by methylglyoxal in combination with NADH, indicating a possible involvement of one or more sulfhydryl group(s) at the active site of the enzyme.

Alcohol Oxidoreductases↗
PubMed1984

Oxidation of lactaldehyde by cytosolic aldehyde dehydrogenase and inhibition of cytosolic and mitochondrial aldehyde dehydrogenase by metabolites.

An enzyme fraction which oxidizes lactaldehyde to lactic acid has been purified from goat liver. This enzyme was found to be identical with the cytosolic aldehyde dehydrogenase. Lactaldehyde was found to be primarily oxidized by this enzyme. Almost 90% of the total lactaldehyde-oxidizing activity is located in the cytosol. Methylglyoxal and glyceraldehyde 3-phosphate were found to be strong competitive inhibitors of this enzyme. Aldehyde dehydrogenase from goat liver mitochondria has also been partially purified and found to be strongly inhibited by these metabolites. The inhibitory effects of these metabolites on both these enzymes are highly pH dependent. The inhibitory effects of both the metabolites have been found to be stronger for the cytosolic enzyme at pH values higher than the physiological pH. For the mitochondrial enzyme, the inhibition with methylglyoxal was more pronounced at higher pH values, whereas stronger inhibition was observed with glyceraldehyde 3-phosphate at physiological pH.

Aldehyde Dehydrogenase↗
PubMed1984

Orthopaedic problems associated with survival in campomelic dysplasia.

In the early part of this century sporadic reports of campomelic dysplasia appeared in the literature, along with reports of other entities, under the term "congenital bowing of the long bones." In 1970 Spranger et al. considered campomelic dysplasia a distinct entity. The terms "camptomelic" and "campomelic" have been used interchangeably in the literature since that time. The patient in the present report is a 6 1/2-year-old white girl with classic long-limbed campomelic dysplasia. The patient has had severe respiratory problems throughout her life. As an infant she was treated by a Pavlik harness for subluxation of the hips. She later required two cervical and two thoracic posterior spinal fusions, as well as release of complex foot deformities and osteotomy of the right tibia. Perioperative complications have been significant. Currently, her height and weight are those of a 2 1/2-year-old child, and she has the bone age of a 3 1/2-year-old child. Nevertheless, she is in first grade at a regular school. Certainly, the prognosis for patients with campomelic dysplasia is guarded, but some survivors may be helped by judicious orthopedic care.

Bone Diseases, Developmental↗
PubMed1983

Studies in antifertility agents--Part XLI : Secosteroids--X : Syntheses of various stereoisomers of (+/-) 2,6 beta -diethyl-7 alpha -ethynyl-3-(p-hydroxyphenyl)-trans-bicyclo[4.3.0]nonan-7 beta-ol.

The syntheses of (+/-) 2 alpha,6 beta -diethyl-7 alpha -ethynyl-3 alpha-(p-hydroxyphenyl)-trans- bicyclo[4.3.0]nonan-7 beta-ol (8), (+/-)2 beta,6 beta-diethyl-7 alpha-ethynyl-3 beta-(p-methoxy-phenyl)-trans-bicyclo[4.3.0]nonan-7 beta-ol 12 and (+/-) 2 alpha,6 beta-diethyl-7 alpha-ethynyl-3 beta-(p-hydroxyphenyl)- trans-bicyclo[4.3.0]nonan-7 beta-ol (18) and their derivatives, which are essentially B-seco-steroids having cis-anti-trans, cis-syn-trans and trans-anti-trans geometries have been carried out. A study of their antiimplantation activities (AI) and receptor binding affinities (RBA) show that trans-anti-trans compounds are biologically most potent, followed by the corresponding cis-anti-trans and cis-syn-trans compounds. The most potent compound 18 is active at 1 mg/kg in rats. Introduction of 7 alpha-ethynyl group increases their AI activity; however, no significant effect on their RBA is observed.

Animals↗
PubMed1983

Antifertility agents. 38. Effect of the side chain and its position on the activity of 3,4-diarylchromans.

In a study of the effect of the substituent on the receptor binding affinity (RBA), estrogenicity, and antiimplantation (AI) activity in trans-3,4-diarylchromans, it has been found that demethylation of trans-2, 2-dimethyl-3-phenyl-4-[p-(beta-pyrrolidinoethoxy)phenyl]-7-methoxychroman (centchroman, 1) to the corresponding 7-hydroxy compound (7) results in a 20-fold increase in RBA (112%) without any appreciable change in AI activity. On the other hand, absence of the pyrrolidinoethyl group from the 4-phenyl residue (6) leads to a drop in both RBA and AI activity. A chain length of two to three carbon atoms and a pyrrolidino ring appear to be necessary for activity in these compounds. It has been found that while the trans isomers with the tertiary aminoalkoxy side chain in the para position of the 4-phenyl radical were the most active, in the corresponding cis-chromans and chromenes, analogues with this chain in the meta position were most active; the ortho substituted compounds of all these series were inactive. In 3-phenyl-substituted compounds, the trans isomer carrying the p-hydroxy substituent (33) was found to be the most active; the corresponding pyrrolidinoethyl ether (13) showed a lower order of activity. The implication of these observations on the mapping of the different subsites on the receptor has been discussed.

Animals↗
PubMed1982

Purification and characterization of NAD and NADP-linked alpha-ketoaldehyde dehydrogenases involved in catalyzing the oxidation of methylglyoxal to pyruvate.

Two alpha-ketoaldehyde dehydrogenases, one catalyzing the oxidation of methylglyoxal to pyruvate with NAD and the other with NADP, were isolated from goat liver and happened to be co-purified. Both the enzymes had been extensively purified to the point where only these two enzymes were present. By affinity chromatography on a thiol-Sepharose column, the two enzymes were separated. Molecular weight of both the enzymes was found to be 42,000 by gel filtration in a Sephadex G-200 column. Electrophoresis on sodium dodecyl sulfate-polyacrylamide gel revealed that the enzymes are composed of single subunits. Interaction with mercurials indicated the presence of SH group(s) in the active site of the NAD-linked enzyme only.

Aldehyde Oxidoreductases↗
PubMed1982

On the interaction of nucleotides and glycolytic intermediates with NAD-linked alpha-ketoaldehyde dehydrogenase.

The effect of different nucleotides and glycolytic intermediates was tested on the NAD-linked and NADP-linked alpha-ketoaldehyde dehydrogenases involved in the oxidation of methylglyoxal to pyruvate. ATP, GTP, and ADP strongly inhibit the NAD-linked enzyme whereas activity of the NADP-linked enzyme remained unaltered. NADP at a concentration much below its catalytic concentration strongly inhibited the NAD-linked enzyme. This NADP inhibition decreased with decreasing of the pH of the incubation medium. Fructose 1,6-bisphosphate stimulated and glyceraldehyde 3-phosphate inhibited the activity of the NAD-linked enzyme whereas dihydroxyacetone phosphate inhibited NADP-linked activity. The stimulatory effect of fructose 1,6-bisphosphate diminished with lowering of the pH value. The various effects by several key metabolites of the glycolytic pathway indicate a possible physiological role for these enzymes.

Adenosine Diphosphate↗
PubMed1982

The effect of a purified guar degrading enzyme on chick growth.

Guar gum, a galactomannan, is growth depressing when fed to chicks. As part of the continuing studies on the mode of action of this and other gums in the intestine, a mannanase has been isolated which degrades guar gum. A commercial hemicellulase was separated into several protein fractions by chromatography on DEAE-cellulose. Only one of these proteins effectively reduced the viscosity of a guar gum solution. Activity towards pectin, rye water extract, and barley water extract was not present in the fraction which degraded guar gum but was found in other fractions at lower concentrations. Graded levels of this purified guar-degrading enzyme were incorporated into chick diets having 2% guar gum. This purified enzyme was effective at levels as low as .6 mg protein/kg diet in preventing growth depression caused by the guar gum and thus permitting growth equivalent to controls. Purity of this mannanase was confirmed by chromatography on QAE-Sephadex at pH 6.0 and by slab-gel electrophoresis at pH 8.4.

Animals↗
PubMed1981

Isolation of methylglyoxal synthase from goat liver.

An enzyme fraction which specifically catalyzes the formation of methylglyoxal from dihydroxyacetone phosphate has been isolated and partially purified from goat liver. The enzyme fraction appears to be substantially free from glyoxalase I, reduced glutathione, and triosephosphate isomerase. Approximately equimolar quantities of methylglyoxal and inorganic phosphate were obtained from dihydroxyacetone phosphate. Formation of methylglyoxal was confirmed by colorimetric and enzymatic estimations as well as by paper chromatography and its spectrum. Glyceraldehyde-3-phosphate, fructose 1,6-bisphosphate, dihydroxyacetone, and glyceraldehyde, failed to act as substrates. The enzyme is inhibited by some phosphorylated compounds and inorganic phosphates.

Animals↗