Stern M L, Phillips A W, Gottlieb A J
J Bacteriol. 1976 Feb;125(2):719-27. doi: 10.1128/jb.125.2.719-727.1976.
Purified L-asparaginase from Serratia marcescens had an apparent-weight average molecular weight of 171,000 to 180,000 as determined by electrophoresis on polyacrylamide gels and by sedimentation equilibrium at low speed in an analytical ultracentrifuge. A subunit molecular weight of 31,500 +/- 1,500 was estimated for the enzyme after treatment with sodium dodecyl sulfate and urea and electrophoresis on polyacrylamide gels; a similar value was obtained by high-speed sedimentation equilibrium in the presence of guanidine hydrochloride. Our data indicate that the Serratia enzyme could have five or six subunits of 32,000 daltons, compared to four subunits of 32,000 daltons in the Escherichia coli enzyme. The Serratia L-asparaginase also appears to be a larger molecule than the enzyme from Erwinia carotovora, Proteus vulgaris, Acinetobacter glutaminasificans, and Alcaligenes eutrophus. The Serratia enzyme, like that from E. caratovora, was more resistant than the E. coli enzyme to dissociation by sodium dodecyl sulfate. This resistance could be due to the finding that the Serratia enzyme had a relatively high hydrophobicity, similar to the enzyme from E. caratovora, when compared with the hydrophobicity of the E. coli enzyme. The isoelectric point of the Serratia enzyme was approximately 5.2. The influence of certain physical characteristics of the enzyme on the biological properties is discussed.
通过在聚丙烯酰胺凝胶上进行电泳以及在分析超速离心机中进行低速沉降平衡测定，粘质沙雷氏菌纯化的L-天冬酰胺酶的表观重均分子量为171,000至180,000。在用十二烷基硫酸钠和尿素处理并在聚丙烯酰胺凝胶上进行电泳后，估计该酶的亚基分子量为31,500±1,500；在盐酸胍存在下通过高速沉降平衡获得了类似的值。我们的数据表明，与大肠杆菌酶的四个32,000道尔顿的亚基相比，粘质沙雷氏菌酶可能有五个或六个32,000道尔顿的亚基。粘质沙雷氏菌L-天冬酰胺酶似乎也是一个比胡萝卜软腐欧文氏菌、普通变形杆菌、谷氨酰胺不动杆菌和嗜水气单胞菌的酶更大的分子。粘质沙雷氏菌酶与胡萝卜软腐欧文氏菌的酶一样，比大肠杆菌酶更耐十二烷基硫酸钠的解离。这种抗性可能是由于发现粘质沙雷氏菌酶与大肠杆菌酶的疏水性相比具有相对较高的疏水性，类似于胡萝卜软腐欧文氏菌的酶。粘质沙雷氏菌酶的等电点约为5.2。讨论了该酶某些物理特性对生物学性质的影响。
