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Biomedical subjects

S Iwata

Publications and source records attributed to S Iwata.

At least 469 records · Page 26Linked to original sources
PubMed1977

Cataractogenic effects of a boron hydride disulfide compound.

The disulfide form but not the sulfhydryl form of a boron hydride compound was found to be cataractogenic. Apparently this compound attaches to the sulfhydryl group of Na-K ATPase in the lens epithelium inactivating this crucial enzyme. The consequence is that a defect in the cation pump activity arises, leading to a rapid influx of Na ions and loss of K ions and marked increase in hydration. These changes are thought to lead to opacification.

Acute Disease↗
PubMed1977

The mode of hydrolysis of a glycan portion of Micrococcus lysodeikticus cell walls by endo-N-acetylglucosaminidase or endo-N-acetylmuramidase isolated from crude barley beta-amylase.

Micrococcus lysodeikticus cell walls were digested with a pI 6.8 endo-N-acetylglucosaminidase or a pI 9.5 endo-N-acetylmuramidase. The digests were further treated with a N-acetylmuramyl-L-alanine amidase of Flavobacterium L-11 enzyme to remove the peptide portion. The products were fractionated by gel filtration and ion-exchange chromatography, and the glycan portion of fractions were analyzed for their average amino sugar chain lengths. The following results were obtained. 1. The glycan portion of the main products in the pI 6.8 enzyme digest consisted of (-N-acetylmuramic acid-N-acetyl-glucosamine-)2-3. 2. The glycan moiety of the pI 9.5 enzyme digest was mainly composed of (-N-acetylglucosamine-N-acetylmuramic acid-)3-4. 3. The glycosidic linkages around the muramic acid 6-phosphate residues which linked to a special structure through a phosphodiester bond were rather refractory to the glycosidase action of both pI 6.8 and 9.5 enzymes.

Acetylglucosaminidase↗
PubMed1976

Studies of the cell envelope of Vibrio para-haemolyticus A55: isolation and purification of bag-shaped peptidoglycan (murein sacculus).

The peptidoglycan (PG) component of the envelope of Vibrio parahaemolyticus A55 was studied in relation to the salt dependency of the organism. A bag-shaped PG (murein sacculus) was isolated and purified by digestion of freshly harvested intact whole cells with sodium dodecyl sulfate (SDS) and then protease treatment. Whole cells lyze in salt-deficient or hypotonic conditions and this can be measured by turbidometry. Lysis is prevented by addition of 0.35 M NaCl or acidification to below pH 4.5. The isolated PG or murein sacculi did not seem to require salt for structural integrity. The PG obtained by the same method from subcellular fractions, that is, envelope fractions, prepared either with or without NaCl, was extensively fragmented. The main amino acids and amino sugars of the murein sacculus were glucosamine, muramic acid, alanine, glutamic acid, 2, 6-diamnopimelic acid (A2pm) in a molar ratio of 0.4:0.6:1.7:0.9:1.0. A polyglucose, which was only degraded by Pseudomonas isoamylase,and poly-beta-hydroxybutyrate (PHBA) were found in the murein sacculus. The murein sacculus of the organism is discussed in comparison with PG of other gram negative bacteria and marine or halophilic microorganisms.

Alanine↗
PubMed1976

Chemical structure of the peptidoglycan of Vibrio parahaemolyticus A55 with special reference to the extent of interpeptide cross-linking.

The chemical structure of the cell wall peptidoglycan of Vibrio parahaemolyticus A55 was studied. Estimation of cross linkages between peptide subunits in the peptidoglycan by dinitrophenylation showed that about 30% of the total 2,6-diaminopimelic acid (A2pm) residues were involved in cross linkages. The presence of interpeptide bridges was also demonstrated by isolating bisdisaccharide peptide subunit dimers from Chalaropsis muramidase digests of the cell wall peptidoglycan by gel filtration followed by ion-exchange column chromatography, although most of the building blocks obtained were uncross-linked disaccharide peptide monomers. The chain length of a glycan moiety of the peptidoglycan obtained by treatment with the L-11 enzyme and gel filtration of the digest was also studied. The chain length varied from 7 to 44, but 30% of the glycan fragments had muramic acid at the reducing end and a chain length of 28 to 44. In conformity with the above structural study it was demonstrated that a particulate enzyme fraction obtained by differential centrifugation of a sonicated preparation of V. parahaemolyticus catalyzed a penicillin-sensitive transpeptidation reaction, using UDP-MurNAc-14C-pentapeptide and UDP-GlcNAc as substrates.

Amino Acids↗