Tokunaga M, Loranger J M, Wu H C
J Biol Chem. 1984 Mar 25;259(6):3825-30.
Prolipoprotein signal peptidase, a unique endopeptidase which recognizes glycyl glyceride cysteine as a cleavage site, was characterized in an in vitro assay system using purified prolipoprotein as the substrate. This enzyme did not require phospholipids for its catalytic activity and was found to be localized in the inner cytoplasmic membrane of the Escherichia coli cell envelope. Globomycin inhibited this enzyme activity in vitro with a half-maximal inhibiting concentration of 0.76 nM. Nonionic detergent, such as Nikkol or Triton X-100, was required for the in vitro activity. The optimum pH and reaction temperature of prolipoprotein signal peptidase were pH 7.9 and 37-45 degrees C, respectively. Phosphatidylglycerol:prolipoprotein glyceryl transferase (glyceryl transferase) activity was measured using [2-3H]glycerol-labeled JE5505 cell envelope and [35S]cysteine-labeled MM18 cell envelope as the donor and acceptor of glyceryl moiety, respectively. 3H and 35S dual-labeled glyceryl cysteine was identified in the product of this enzymatic reaction. The optimal pH and reaction temperature for glyceryl transferase were pH 7.8 and 37 degrees C, respectively.
前脂蛋白信号肽酶是一种独特的内肽酶，它将甘氨酰甘油半胱氨酸识别为切割位点，该酶在以纯化的前脂蛋白为底物的体外测定系统中得到了表征。这种酶的催化活性不需要磷脂，并且发现它定位于大肠杆菌细胞膜的内膜中。球霉素在体外抑制这种酶的活性，其半数最大抑制浓度为0.76 nM。体外活性需要非离子洗涤剂，如尼康醇或 Triton X-100。前脂蛋白信号肽酶的最适pH值和反应温度分别为pH 7.9和37-45℃。磷脂酰甘油：前脂蛋白甘油基转移酶（甘油基转移酶）活性的测定分别使用[2-3H]甘油标记的JE5505细胞膜和[35S]半胱氨酸标记的MM18细胞膜作为甘油基部分的供体和受体。在该酶促反应的产物中鉴定出3H和35S双标记的甘油半胱氨酸。甘油基转移酶的最佳pH值和反应温度分别为pH 7.8和37℃。
