STRUCTURAL AND FUNCTIONAL-CHARACTERIZATION OF HUMAN SULFOTRANSFERASES

The human aryl sulfotransferases HAST4 and HAST4v vary by only two ami no acids but exhibit markedly different affinity towards the sulfonate acceptor p-nitrophenol and the sulfonate donor 3'-phosphoadenosine-5' -phosphosulfate (PAPS). To determine the importance of each of these a mino acid differences, chimeric constructs were made of HAST4 and HAST 4v. By attaching the last 120 amino acids of HAST-4v to HAST4 (changin g Thr235 to Asn235) we have been able to produce a protein that has a K-m for PAPS similar to HAST4v. The reverse construct, HAST4v/4 produc es a protein with a K-m for PAPS similar to HAST4. These data suggests that the COOH-terminal of sulfotransferases is involved in co-factor binding. (C) 1998 Elsevier Science Ireland Ltd. All rights reserved.