Slomiany B L, Liau Y H, Zalesna G, Slomiany A
Dental Research Center, New Jersey Dental School, University of Medicine and Dentistry of New Jersey, Newark 07103-2425.
Alcohol Clin Exp Res. 1988 Dec;12(6):774-9. doi: 10.1111/j.1530-0277.1988.tb01344.x.
In vitro sulfation of mucus glycoprotein by sulfotransferase from rat submandibular salivary gland and the effect of ethanol on this enzyme activity was investigated. Subcellular fractionation studies revealed that the enzyme which catalyzes the transfer of sulfate ester group from 3'-phosphoadenosine-5'-phosphosulfate to submandibular gland mucus glycoprotein is associated with Golgi-rich membrane fraction. The sulfotransferase enzyme exhibited optimum activity at pH 6.8 in the presence of 0.5% Triton X-100, 4 mM MgCl2, and 25 mM NaF. The enzyme was equally capable of sulfation of the desulfated intact as well as proteolytically degraded desulfated glycoprotein preparations, whereas the acceptor capacity of the intact mucus glycoprotein was 70% lower. The submandibular gland sulfotransferase activity was inhibited by ethanol. The rate of inhibition of mucus glycoprotein sulfation was proportional to the concentration of ethanol up to 0.4 M, at which concentration a 39% reduction in the sulfotransferase activity occurred. The apparent Km value of the enzyme for salivary mucus glycoprotein was 11.1 microM, and the Kl in the presence of ethanol was 0.93 M. The synthesized 35S-labeled glycoprotein gave on CsCl equilibrium density gradient centrifugation 35S-labeled peak which coincided with that of the glycoprotein. Alkaline borohydride treatment of this glycoprotein led to the liberation of the label into the acidic oligosaccharide alditol fraction. As the inhibition by ethanol of sulfotransferase enzyme occurred below its isosmotic concentration to plasma, the observed effect could also be detrimental to salivary mucus glycoprotein sulfation in vivo.
研究了大鼠下颌下唾液腺硫酸转移酶对黏液糖蛋白的体外硫酸化作用以及乙醇对该酶活性的影响。亚细胞分级分离研究表明，催化硫酸酯基团从3'-磷酸腺苷-5'-磷酸硫酸转移至下颌下腺黏液糖蛋白的酶与富含高尔基体的膜部分相关。硫酸转移酶在pH 6.8、存在0.5% Triton X-100、4 mM MgCl2和25 mM NaF的条件下表现出最佳活性。该酶对脱硫酸化的完整糖蛋白制剂以及经蛋白水解降解的脱硫酸化糖蛋白制剂同样具有硫酸化能力，而完整黏液糖蛋白的受体能力则低70%。下颌下腺硫酸转移酶活性受到乙醇的抑制。黏液糖蛋白硫酸化的抑制速率与乙醇浓度成正比，直至0.4 M，在此浓度下硫酸转移酶活性降低39%。该酶对唾液黏液糖蛋白的表观Km值为11.1 microM，在存在乙醇的情况下Kl为0.93 M。合成的35S标记糖蛋白在CsCl平衡密度梯度离心中产生的35S标记峰与糖蛋白的峰重合。用碱性硼氢化钠处理该糖蛋白导致标记物释放到酸性低聚糖糖醇部分。由于乙醇对硫酸转移酶的抑制发生在其与血浆等渗浓度以下，因此观察到的效应在体内也可能对唾液黏液糖蛋白的硫酸化产生不利影响。
