All sulfotransferases require adenosine 3′,5′-bisphosphate (PAP) or 3′-phospho adenosine 5′-phosphosulfate (PAPS) to catalyze sulfuryl group transfer. Thus, PAP is used as cofactor by phenol sulfotransferase (PST) for moving sulfuryl group from p-nitrophenyl sulfate (pNPS) to other phenols. PST also tightly binds to a variety of nucleotides and we found that sulfuryl group can be released from pNPS in the presence of several nucleotides other than PAP or PAPS. Binding of nucleotides by PST is rather non-selective. We determined binding constants of a variety of nucleotides and examined their potential as cofactors or substrates of phenol sulfotransferase. Structure and functional groups of nucleotides and their requirements for PST binding are examined. We found that even ribose and adenine, two major components of the adenosine nucleotides, tightly bound to PST. Some nucleotides, such as adenosine 2′, 5′bisphosphate and AMP, accept and transfer sulfuryl group analogue to PAP with less efficiency. Other nucleotides, such as ADP, involve in both sulfuryl group transfer and hydrolysis of phospho ester after sutfation. While unable to. hydrolyze pNPS directly, PST was found to hydrolyze PAPS at alkaline pH. Kinetic data and NMR are Used to determine the reaction pathways of PST catalyzed sulfation and hydrolysis. In this presentation, we would like to demonstrate that PST uses a broad range of nucleotides as substrate or cofactor for sulfuryt group transfer. (Supported by Grant NSC 86-2311-B-009-002 of National Science Council, Taian).
|State||Published - 1 Dec 1997|