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Biomedical subjects

N Sharon

Publications and source records attributed to N Sharon.

At least 253 records · Page 14Linked to original sources
PubMed1973

The purification, composition and specificity of wheat-germ agglutinin.

1. The purification of wheat-germ agglutinin from commercial wheat germ is described. By ion-exchange chromatography three active proteins (isolectins) were separated, one of which was examined in detail. 2. The amino acid composition is unusual, as 20% of residues are half-cystine and 21% are glycine. Unlike most lectins and contrary to previous reports, this protein is not a glycoprotein. 3. The efficiency of various saccharides as inhibitors of the agglutination reaction was investigated and from this the specificity of the binding site was inferred. Of monosaccharides, only derivatives of glucose with a 2-acetamido group and a free 3-hydroxyl group are effective inhibitors, and glycosides of either anomeric configuration are bound. Oligosaccharides are much more powerful inhibitors of agglutination than are monosaccharides. 4. It is proposed that the binding site consists of three or four subsites with differing specificities, in a cleft in the molecule resembling that proposed for hen's-egg-white lysozyme.

Amino Acids↗
PubMed1972

Role of the penicillin-sensitive transpeptidation reaction in attachment of newly synthesized peptidoglycan to cell walls of Micrococcus luteus.

Cell-wall preparations of Micrococcus luteus (lysodeikticus) catalyze in vitro peptidoglycan synthesis from UDP N-acetyl-D-glucosamine, UDP N-acetylmuramic acid-pentapeptide, and glycine. Newly synthesized peptidoglycan is partially cross-linked by a transpeptidation reaction with concomitant release of C-terminal D-alanine. Penicillin not only strongly inhibits release of D-alanine (98% at 1 mug/ml), but also markedly inhibits incorporation of acetylglucosamine and N-acetylmuramic acid-pentapeptide into the preformed cell-wall peptidoglycan. The simplest explanation for the results is that incorporation of newly synthesized strands of peptidoglycan and their attachment to "older" cell-wall peptidoglycan proceeds mainly by transpeptidation and that transglycosylation is responsible only for part of the elongation of the pre-existing peptidoglycan. Another possibility is that incorporation occurs by transglycosylation, but it cannot continue without concurrent formation of peptide cross-bridges.

Amino Acids↗
PubMed1972

Responses of lymphocytic choriomeningitis carrier mice to X-ray-induced lymphoma.

The data presented in this paper define the interrelationship between two endogenous diseases in the same host. The Haas strain of germfree mice with congenitally acquired persistent lymphocytic choriomeningitis (LCM) virus infection developed the X-ray-induced lymphatic leukemia independent of LCM viremia. The immunoproliferative LCM-related lesions appeared after age 7 months, and the radiogenic lymphatic leukemia appeared earlier or during the same age period. Both diseases evolved with distinctive lesions at the appropriate time, with no evidence of interference nor of synergism between the two syndromes. The Haas strain of mice showed an unusual sensitivity to X rays which was associated with depletion of blood components and coincident death. The sensitivity of the mice to X rays might be a characteristic of the Haas mouse or the result of an LCM virus-induced alteration in hematopoiesis.

Animals↗