Nucleotide binding and sulfation catalyzed by phenol sulfotransferase

Abstract

The sulfation of a nucleotide is an indispensable step for the sulfuryl group transfer in a biological system. The product and cosubstrate of sulfotransferase in physiological condition are adenosine 3',5'-bisphosphate (PAP) and 3'-phospho adenosine 5'-phosphosulfate (PAPS), respectively. We find that ribose and adenine, two major parts of the adenosine nucleotide, bind tightly to phenol sulfotransferase (PST) separately, and various nucleotides also bind tightly to PST. We determine the dissociation constants of a variety of nucleotides and examine their potential as cofactors or cosubstrates of PST. Using 4-nitrophenyl sulfate as the sulfuryl group donor, three nucleotides, adenosine 5'-monophosphate (AMP), adenosine 2',5'-bisphosphate (2',5'-PAP), and adenosine 2':3' cyclic phosphate 5'-phosphate (2':3'-cyclic PAP), are shown here for the first time to be sulfated at 5'-phopho position by a PST catalyzed reaction. Spectrophotometry, HPLC, and P-31 NMR are used to determine the activity of PST and identify the sulfated nucleotides. The V-max of PST and K-m of these nucleotides are determined when they are used as cofactors or cosubstrates for the sulfuryl group transfer. The existence and possible physiological significance of these newly reported binding and sulfation of nucleotides by PST in biology is yet to be discovered. (C) 2000 Academic Press.