Browsing by Author "GEETHA, M"

Now showing 1 - 3 of 3
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    ANOMER SPECIFICITY OF THE 14-KDA GALACTOSE-BINDING LECTIN - A REAPPRAISAL
    (JOURNAL OF BIOSCIENCES, 1995) APPUKUTTAN, PS; GEETHA, M; ANNAMMA, KI
    A beta-anomer preference among galactosides has been attributed to the S-type 14 kDa galactose binding lectin. Here the anomeric preference of this lectin from bovine brain (BBL) is reexamined using inhibition of lectin-mediated haemagglutination, binding of the lectin to dot-blotted glycoproteins and affinity electrophoresis of the lectin through polysaccharide-containing gels. 1-O-methyl alpha-D-galactoside was 8 times better inhibitor of BBL than the corresponding beta-anomer. The terminal galactose in bovine thyroglobulin (exclusively alpha-linked) were also nearly 8 times more inhibitory than those in asialofetuin (exclusively beta-linked). The terminal alpha-galactose-containing endogenous glycoproteins of bovine brain were nearly 4 times better inhibitors of BBL than laminin. Removal of terminal alpha-galactose units by alpha-galactosidase fully abolished the BBL binding of thyroglobulin and endogenous glycoproteins. BBL was also sugar-specifically retarded by polyacrylamide gel containing guar galactomannan which bears only alpha-linked galactose. Data indicated that alpha-galactosides were sometimes better than their beta-anomers in binding to BBL. The significance of this observation to the physiological role of galactose-binding lectins is discussed.
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    BRAIN 14 KDA LECTIN PREFERS ALPHA-ANOMER OF GALACTOSE
    (JOURNAL OF NEUROCHEMISTRY, 1994) APPUKUTTAN, PS; GEETHA, M; ANNAMMA, KI
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    EPITOPES RECOGNIZED BY SERUM ANTI-ALPHA-GALACTOSIDE ANTIBODY ARE PRESENT ON BRAIN GLYCOPROTEINS IN MAN
    (JOURNAL OF BIOSCIENCES, 1993) JAISON, PL; KANNAN, VM; GEETHA, M; APPUKUTTAN, PS
    Naturally occurring serum IgG against terminal alpha-galactoside epitopes (anti-Gal), present exclusively in man, apes and old world monkeys, was used as probe for these epitopes in human brain. Human brain grey matter soluble glycoproteins enriched in alpha-galactosyl groups by affinity chromatography on jacalin-sepharose, specifically binds to human anti-Gal in immuno dot blots. Anti-Gal recognized exclusively the terminal alpha-galactoside epitope in human brain glycoproteins since binding was abolished by the presence of 1-0-methyl alpha-D-galactopyranoside as well as by pretreatment of glycoproteins with coffee bean alpha-galactosidase. Anti-Gal-peroxidase staining of jacalin-binding human brain glycoproteins in western immuno blots revealed mainly five anti-Gal-binding polypeptides with M(r) (in kDa) of 94, 108, 180, 210 and 230 respectively. Since the presence of anti-Gal in higher animals accompanies suppression of the corresponding epitope in most tissues, apparently to maintain immunological balance, possible implications of the above observation for autoimmunity, tumor metastasis and infection are discussed.