MARIKAR, YZACHARIAH, BBASU, D2012-12-042012-12-041992INDIAN JOURNAL OF BIOCHEMISTRY & BIOPHYSICS. 29; 3; 255-261https://dspace.sctimst.ac.in/handle/123456789/241Neuronal and glial surface glycoproteins have been isolated from human foetal brains by affinity chromatography on 8 M urea or 6 M guanidine-treated Con A-Sepharose 4B at 4-degrees-C and three groups of glycoproteins of molecular mass 65-73 kDa, 52-63 kDa and 43-48 kDa have been identified on SDS/PAGE. These glycoproteins exhibited anomalous behaviour on SDS/PAGE, indicating the existence of a gradation of mutually interconvertible protein-SDS aggregates in dynamic equilibrium with one another. Deglycosylation and deacylation did not alter the SDS/PAGE multiple band pattern. Purified glycoproteins contained 160 +/- 90-mu-g carbohydrate/mg protein, and a sialic acid content of 25 +/- 5 nmole/mg protein. The N-terminals were blocked. The glycoproteins moved preferentially on acid/urea/PAGE. Sepharose 6B gel filtration in the absence of lipid and detergents resolved the glycoproteins into an excluded peak I and a low molecular mass peak II. Peaks I and II were non-interconvertible on Sepharose 6B gel filtration or on reversed phase HPLC in an isopropanol/water/TFA gradient system. Both peaks rendered a single fast moving band of identical mobility on acid/urea/PAGE, suggesting that peak I was possibly a micellar aggregate of the monomeric peak II. The glycoproteins were refractory to digestion by trypsin or pronase and reacted identically towards various lectins. Attempts to raise antibodies in rabbit against the isolated glycoproteins were unsuccessful. The physicochemical properties apparently reflect an inherent tendency of these glycoproteins to form self aggregates, a characteristic of amphipathic membrane proteins.Biochemistry