|
PTL II is an acidic dimeric glycoprotein with a molecular weight of about 54,000. Subunits can be dissociated in the absence of reducing agents and migrate in SDS-PAGE as a single band. The isoelectric point of this lectin is about pH 5.5.
Like PTL I, this lectin binds preferentially to galactosides, with N-acetylgalactosamine being the most inhibitory monosaccharide. However, in contrast to PTL I, this lectin prefers the beta anomeric configuration. PTL II shows a high affinity toward blood group H structures and the T-antigen. In general, though, PTL II has lower affinities for inhibiting sugars than does PTL I. PTL I and PTL II also differ in their erythrocyte agglutinating properties. Tissue staining results indicate preference for some vascular elements with overall lighter staining than obtained with PTL I. |