Alhadeff J A, Holzinger R T
Biochem J. 1982 Jan 1;201(1):95-9. doi: 10.1042/bj2010095.
An atypical thermolabile species of Hex B (hexosaminidase B) has been found in metastatic-tumour sites of human liver which has a thermostability curve similar to that of Hex A (hexosaminidase A), which is present in decreased amounts relative to the Hex A isoenzyme, and which exhibits decreased relative activity at acidic pH values (2.6-3.6) when compared with control-liver Hex B. This atypical Hex B isoenzyme has a normal apparent Michaelis constant (0.6 mM) for 4-methylumbelliferyl 2-deoxy-2-acetamido-beta-D-glucopyranoside. The presence of this atypical Hex B suggests that variant beta-chains are being produced in metastatic-tumour tissue.
在人类肝脏的转移瘤部位发现了一种非典型的热不稳定型己糖胺酶B(Hex B),其热稳定性曲线与己糖胺酶A(Hex A)相似,相对于Hex A同工酶,其含量降低,并且与对照肝脏的Hex B相比,在酸性pH值(2.6 - 3.6)下表现出相对活性降低。这种非典型的Hex B同工酶对4 - 甲基伞形酮基2 - 脱氧 - 2 - 乙酰氨基 - β - D - 吡喃葡萄糖苷具有正常的表观米氏常数(0.6 mM)。这种非典型Hex B的存在表明转移瘤组织中正在产生变异的β链。