Isolation of platelet plasma membrane proteins by affinity chromatography

A general method for the labelling and recovery of platelet membrane proteins is described. This method is based on the principle of labelling cell membrane proteins with reagents containing haptenic groups. The labelled proteins can then be isolated by affinity chromatography, using antibodies against the haptenic groups on the labelling reagents. Two compounds representing different groups of reagents were synthesized and used: 2,4-dinitrophenyl-beta-alanine hydrazide, which is a labelling reagent for glycoproteins, and diazodiiodoarsanilic acid, which binds to externally exposed membrane proteins. 2,4-Dinitrophenyl-beta-alanine hydrazide binds to aldehydes formed from oxidized sialic acid. Three main proteins were isolated using this reagent. Using diazodiiodoarsanilic acid, a protein having a molecular weight of 85,000 was labelled and later isolated in an affinity column with anti-arsanilic acid antibodies.