Purification and kinetic characterization of a phenol-sulfating form of phenol sulfotransferase from human brain.

The identification of three forms of phenol sulfotransferase (PST) in human brain and the subsequent purification and kinetic characterization of a phenol-sulfating form of the enzyme are described. Two forms of PST which were capable of conjugating phenol and a third form which sulfated dopamine were resolved from one another using DEAE-cellulose chromatography. One of the phenol-sulfating forms (P1-PST) was subsequently purified on Affi-Gel blue and Sephacryl S-200, giving a final purification of almost 390-fold, with an overall yield of approximately 5%. The purified enzyme was sensitive to NaCl and showed an optimum for phenol conjugation at pH 8.5. Kinetic analysis demonstrated that sulfation by P1-PST proceeds via a sequential ordered, bi-substrate reaction mechanism, where 3'-phosphoadenosine-5'-phosphosulfate (PAPS) is the leading substrate. The true Km and Kia values for PAPS were both 0.35 microM, while the true Km value for phenol was 2.8 microM.