ISSN:
1573-4919
Keywords:
clam plasma lectin
;
affinity purification
;
galactose
;
combining site
;
steric hindrance
;
hydrophobic region
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Chemistry and Pharmacology
,
Medicine
Notes:
Abstract The marine blood clam species Anadara granosa (L) belong to arcidae, a family with some extraordinary haematological features. The plasma of this species exhibited strong haemagglutinating activities, from which a galactosyl binding lectin, Anadarin P, was purified in a single step affinity chromatography using Sepharose 4B-asialofetuin as an affinity matrix. The purified lectin, eluted with lactose, was found to be homogeneous by alkaline polyacrylamide disc gels, gel-filtration and isoelectric focusing. Native Mr of the lectin was 130,000 having a PI value of 6.82 and was composed of two subunits of Mr 17,000 and Mr 16,000 which were noncovalently bound. The lectin was remarkably thermostable; the agglutinating titre remained unchanged over a wide range of pH (from 5 to 10) but increased with neuraminidase treated rabbit erythrocytes. Anadarin P combining site has been proposed to be small pocket-like structure which recognised only C-3 and C-4 hydroxyl groups of D-galactose. Presence of bulky groups at C-2 and C-6 exert strong steric hindrance as L-arabinose, 2-deoxy-D-galactose and D-xylose are better inhibitors than D-galactose. The lectin fails to differentiate methyl substituted galactosides as both α- and β- methyl galactosides are equally active; but in case of substituted phenyl glycosides, the lectin shows different affinity towards a and (3 anomers. The avidity of the lectin to bind the aromatic aglycons of galactosides suggests the presence of a hydrophobic region in the combining site. Interactions with some dissaccharides indicate the presence of an extended area near the monosaccharide binding site.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00230405
Permalink