Landsiedel R, Pabel U, Engst W, Ploschke J, Seidel A, Glatt H
German Institute of Human Nutrition (DIfE), Department of Toxicology, Potsdam-Rehbruecke, Germany.
Biochem Biophys Res Commun. 1998 Jun 9;247(1):181-5. doi: 10.1006/bbrc.1998.8756.
The benzylic alcohol 1-hydroxyethylpyrene (1-HEP) is activated to a mutagen by sulfotransferases. The sulfuric acid ester formed is difficult to detect, as it is rapidly hydrolysed back to the alcohol. Incubation of the individual enantiomers of 1-HEP with human hydroxysteroid sulfotransferase (hHST) or estrogen sulfotransferase (hEST), expressed in bacteria, led to the formation of the other enantiomer. The rates of sulfation were determined from the initial rates of chiral inversion of the alcohol, knowing that hydrolysis follows an SN1 mechanism and therefore produces racemic alcohol. hEST showed high enantioselectivity for S-1-HEP, whereas hHST strongly preferred the R-enantiomer. The rates of sulfation of the preferred enantiomers were high, similar to those for the prototype substrates of hEST (beta-estradiol) and hHST (dehydroepiandrosterone). Moreover, after a 30-min incubation of S-1-HEP with hEST, 95% of the recovered alcohol showed the R-configuration, indicating that several cycles of sulfation and hydrolysis had led to the depletion of one enantiomer and to the enrichment of the other enantiomer.
苄醇1-羟乙基芘（1-HEP）可被磺基转移酶激活成为诱变剂。所形成的硫酸酯难以检测，因为它会迅速水解回醇类。将1-HEP的各个对映体与在细菌中表达的人羟基类固醇磺基转移酶（hHST）或雌激素磺基转移酶（hEST）一起孵育，会导致形成另一种对映体。已知水解遵循SN1机制，因此会产生外消旋醇，根据醇的手性转化初始速率来确定硫酸化速率。hEST对S-1-HEP表现出高对映选择性，而hHST则强烈偏好R-对映体。优选对映体的硫酸化速率很高，与hEST的原型底物（β-雌二醇）和hHST的原型底物（脱氢表雄酮）的硫酸化速率相似。此外，将S-1-HEP与hEST孵育30分钟后，回收的醇类中有95%呈现R-构型，这表明硫酸化和水解的几个循环导致一种对映体耗竭，另一种对映体富集。
