Labeling of platelet surface glycoproteins with biotin derivatives

We describe a non-radioactive method for the labeling of platelet surface proteins, consisting of platelet protein biotinylation by means of N-hydroxysuccinimido-biotin (NHS-B) and biotin-hydrazide (H-B); NHS-B labels proteins amino residues while H-B binds to periodate-modified sialoglycoproteins. Washed platelets were biotinylated and protein bands were detected after SDS-electrophoresis and western-blot using avidin-peroxidase and luminol as substrate to enhance the signal which was then detected by X-ray film. Biotin-labeled platelet proteins were also immunoprecipitated with monoclonal antibodies against glycoproteins Ib and the IIb-IIIa complex. The use of periodate induced biotinylation is the method of choice for labeling platelet surface glycoproteins while NHS-B also labels internal proteins. The sensitivity of this new procedure is similar to that obtained with radiolabeling techniques; biotinylation does not interfere with the antigenic properties of Ib and IIb-IIIa glycoproteins.