Plasma anti-alpha-galactoside antibody binds to serine- and threonine-rich peptide sequence of apo(a) subunit in Lp(a)

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dc.contributor.authorGeetha, M
dc.contributor.authorKalaivani, V
dc.contributor.authorSabarinath, PS
dc.contributor.authorAppukuttan, PS
dc.date.accessioned2017-03-10T03:28:04Z
dc.date.available2017-03-10T03:28:04Z
dc.date.issued2014
dc.description.abstractLipoprotein(a) immune complexes [Lp(a) IC] of varying particle density obtained by ultracentrifugation of plasma from normal healthy donors were markedly dominated by IgG. Lp(a) and immunoglobulins were liberated from plasma Lp(a) IC by treatment with melibiose, a sugar specific for circulating anti-alpha-galactoside antibody (anti-Gal). Upon incubation with plasma lipoprotein fraction anti-Gal but not the alpha-glucoside-specific antibody from human plasma formed de novo IC with Lp(a). Binding of Lp(a) sugar-reversibly enhanced the fluorescence of FITC-labeled anti-Gal as did binding of alpha-galactoside-containing glycoproteins. This effect apparently due to conformational shift in the Fc region of the antibody was also produced by apo(a) subunit separated from Lp(a) and de-O-glycosylated apo(a) but not by any other plasma lipoproteins or by Lp(a) pre-incubated with the O-glycan-specific lectin jacalin. O-Glycans and their terminal sialic acid moieties in apo(a) of circulating Lp(a)-anti-Gal IC, in contrast to those in pure Lp(a), were inaccessible to jacalin and anion exchange resin, respectively. Unlike other plasma lipoproteins, Lp(a) inhibited Griffonia simplicifolia isolectin B4 which also accommodates serine- and threonine-rich peptide sequence (STPS) as surrogate ligand to alpha-galactosides at its binding site. Results suggest that anti-Gal recognizes STPS in the O-glycan-rich regions of apo(a) subunit in Lp(a) which contains no alpha-linked galactose.
dc.identifier.citation31 ,4;289-298en_US
dc.identifier.uri10.1007/s10719-014-9521-2
dc.identifier.urihttps://dspace.sctimst.ac.in/handle/123456789/10237
dc.publisherGLYCOCONJUGATE JOURNAL
dc.subjectBiochemistry & Molecular Biology
dc.titlePlasma anti-alpha-galactoside antibody binds to serine- and threonine-rich peptide sequence of apo(a) subunit in Lp(a)
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