Chemoenzymatic synthesis of PSGL-1 glycopeptides: Sulfation on tyrosine affects glycosyltransferase-catalyzed synthesis of the O-glycan

PSGL-1 is the primary glycoprotein ligand for P-selectin during the inflamm atory response. Interestingly, the N-terminal sequence, containing both a s ite of tyrosine sulfation and an O-glycan, has been shown to bind to P-sele ctin with an affinity similar to full-length PSGL-1. To further characteriz e this system, the synthesis of glycopeptides from PSGL-1 was undertaken. T he synthesis involved both soIution- and solid-phase synthesis, as well as enzymatic transformations. During the synthesis, notable reactivity differe nces of the glycosyltransferases toward sulfated and unsulfated versions of the same glycopeptides were observed. (C) 2000 Elsevier Science Ltd. All r ights reserved.