Sulfuryl transfer: The catalytic mechanism of human estrogen sulfotransferase

被引:195
作者
Zhang, HP
Varmalova, O
Vargas, FM
Falany, CN
Leyh, TS
机构
[1] Yeshiva Univ Albert Einstein Coll Med, Dept Biochem, Bronx, NY 10461 USA
[2] Univ Alabama, Dept Pharmacol & Toxicol, Birmingham, AL 35294 USA
关键词
D O I
10.1074/jbc.273.18.10888
中图分类号
Q5 [生物化学]; Q7 [分子生物学];
学科分类号
071010 ; 081704 ;
摘要
Estrogen sulfotransferase (EST) catalyzes the transfer of the sulfuryl group from 3'-phosphoadenosine 5'-phosphosulfate (PAPS) to 17 beta-estradiol (E-2), The sulfation of E-2 prevents it from binding to, and thereby activating, the estrogen receptor. The regulation of EST appears to be causally linked to tumorigenesis in the breast and endometrium. In this study, recombinant human EST is characterized, and the catalytic mechanism of the transfer reaction is investigated in ligand binding and initial rate experiments. The native enzyme is a dimer of 35-kDa subunits, The apparent equilibrium constant for transfer to E-2 is (4.5 +/- 0.2) x 10(3) at pH 6.3 and T = 25 +/- 2 degrees C. Initial rate studies provide the kinetic constants for the reaction and suggest a sequential mechanism. E-2 is a partial substrate inhibitor (K-i = 80 +/- 5 nM). The binding of two E-2 per EST subunit suggests that the partial inhibition occurs through binding at an allosteric site. In addition to providing the dissociation constants for the ligand-enzyme complexes, binding studies demonstrate that each substrate binds independently to the enzyme and that both the E.PAP.E2S and E.PAP.E-2 dead-end complexes form. These results strongly suggest a Random Ri Ri mechanism with two dead-end complexes.
引用
收藏
页码:10888 / 10892
页数:5
相关论文
共 27 条
  • [1] BRADFORD MM, 1976, ANAL BIOCHEM, V72, P248, DOI 10.1016/0003-2697(76)90527-3
  • [2] COMPLETE TYROSINE-O-SULFATION OF GASTRIN IN NEONATAL RAT PANCREAS
    BRAND, SJ
    ANDERSEN, BN
    REHFELD, JF
    [J]. NATURE, 1984, 309 (5967) : 456 - 458
  • [3] Cleland W W, 1979, Methods Enzymol, V63, P103
  • [4] Cleland W. W., 1970, ENZYMES, P1
  • [5] DUFFEL MW, 1981, J BIOL CHEM, V256, P1123
  • [6] BACTERIAL EXPRESSION AND CHARACTERIZATION OF A CDNA FOR HUMAN LIVER ESTROGEN SULFOTRANSFERASE
    FALANY, CN
    KRASNYKH, V
    FALANY, JL
    [J]. JOURNAL OF STEROID BIOCHEMISTRY AND MOLECULAR BIOLOGY, 1995, 52 (06) : 529 - 539
  • [7] STEROID SULFATION BY EXPRESSED HUMAN CYTOSOLIC SULFOTRANSFERASES
    FALANY, CN
    WHEELER, J
    OH, TS
    FALANY, JL
    [J]. JOURNAL OF STEROID BIOCHEMISTRY AND MOLECULAR BIOLOGY, 1994, 48 (04) : 369 - 375
  • [8] Falany JL, 1996, CANCER RES, V56, P1551
  • [9] FALANY JL, 1998, IN PRESS ONCOL RES
  • [10] FROMM HJ, 1975, INITIAL RATE ENZYME, P145