Huseby N E
Biochim Biophys Acta. 1978 Feb 10;522(2):354-62. doi: 10.1016/0005-2744(78)90069-4.
A study of the multiple forms of gamma-glutamyltransferase ((gamma-glutamyl)-peptide:amino acid gamma-glutamyltransferase, EC 2.3.2.2) in normal human liver, bile and serum are reported. An amphiphilic form of the enzyme was demonstrated in all three samples. When solubilized with detergent, estimated values for Stoke's radius of 48 A and sedimentation coefficient of 5 S were obtained for this form. A hydrophilic form was also present in serum and bile, which showed identical properties to the enzyme form obtained after papain-treatment of the three samples. The Stoke's radius was found to be 37 A, and the sedimentation coefficient 5 S. It was concluded that the heterogeneity of enzyme activity found both on gel filtration and on electrophoresis was due to aggregates of the amphiphilic form with lipids and other proteins, and could not be ascribed to the presence of isoenzymes.
本文报道了对正常人肝脏、胆汁和血清中γ-谷氨酰转移酶（（γ-谷氨酰）肽：氨基酸γ-谷氨酰转移酶，EC 2.3.2.2）多种形式的研究。在所有三个样本中均证实了该酶的一种两亲形式。用去污剂溶解后，该形式的斯托克斯半径估计值为48 Å，沉降系数为5 S。血清和胆汁中还存在一种亲水形式，其性质与用木瓜蛋白酶处理这三个样本后得到的酶形式相同。发现斯托克斯半径为37 Å，沉降系数为5 S。得出的结论是，在凝胶过滤和电泳中发现的酶活性异质性是由于两亲形式与脂质和其他蛋白质的聚集，而不能归因于同工酶的存在。
