Barash V, Riskin A, Shafrir E, Waddell I D, Burchell A
Department of Biochemistry, Hadassah University Hospital, Jerusalem, Israel.
Biochim Biophys Acta. 1991 Jan 23;1073(1):161-7. doi: 10.1016/0304-4165(91)90197-o.
The existence of the enzyme glucose-6-phosphatase (G6Pase) in early and term human placenta was investigated by comparing the characteristics of placental microsomal glucose 6-phosphate (G6P) hydrolytic activity and liver G6Pase. Placental microsomes exhibited similar apparent Km values for G6P and beta-glycerophosphate in intact and deoxycholate-treated microsomes, heat stability at acidic pH, low latency of mannose 6-phosphate hydrolysis, very low activity of pyrophosphate: glucose phosphotransferase, and undetectable [U-14C]G6P transport into the placental microsomes, all of which indicated that specific G6Pase activity does not exist in placenta. Immunological evidence of the absence of both 36.5 kDa and T2 proteins, which represent the G6Pase catalytic protein and the phosphate/pyrophosphate transporter protein, respectively, confirmed that early and term human placenta are devoid of the multicomponent G6Pase enzyme.
通过比较胎盘微粒体葡萄糖6-磷酸（G6P）水解活性和肝脏葡萄糖-6-磷酸酶（G6Pase）的特性，研究了早期和足月人胎盘中G6Pase酶的存在情况。完整的和经脱氧胆酸盐处理的胎盘微粒体对G6P和β-甘油磷酸表现出相似的表观Km值，在酸性pH下具有热稳定性，甘露糖6-磷酸水解的潜伏性低，焦磷酸：葡萄糖磷酸转移酶的活性非常低，并且未检测到[U-14C]G6P转运到胎盘微粒体中，所有这些都表明胎盘中不存在特异性G6Pase活性。分别代表G6Pase催化蛋白和磷酸盐/焦磷酸盐转运蛋白的36.5 kDa和T2蛋白均不存在的免疫学证据证实，早期和足月人胎盘缺乏多组分G6Pase酶。
