Synthesis of sulfur isotope-labeled sulfate donor, 3'-phosphoadenosine-5'-phosphosulfate, for studying glycosaminoglycan functions.

The biological activity of glycosaminoglycans (GAGs) depends greatly on the sulfation pattern present within the GAG chain. Chemical biology of GAGs can be further advanced by preparation of sulfur-isotope-enriched sulfated GAGs. 3'-Phosphoadenosine-5'-phosphosulfate (PAPS) serves as a universal sulfate donor in the sulfation of GAGs by sulfotransferases. Therefore, synthesis of PAPS carrying sulfur isotopes is critical in the preparation of labeled GAGs for biochemical studies. Here we describe a robust in vitro enzymatic synthesis of sulfur isotope-enriched PAPS which allows for heavy- or radio-isotope labeling of GAG chains.