Peters G, Saborowski R, Mentlein R, Buchholz F
Institut für Meereskunde, Abteilung Zoologie, Kiel, Germany.
Comp Biochem Physiol B Biochem Mol Biol. 1998 Aug;120(4):743-51. doi: 10.1016/s0305-0491(98)10073-1.
Two forms of the chitinolytic enzyme N-acetyl-beta-D-glucosaminidase (NAGase, EC 3.2.1.52) have been isolated from the Antarctic krill, Euphausia superba, in order to study their potential role in temperature adaptation processes. A chromatographic protocol was developed that allowed complete separation of the two enzyme forms, named NAGase B and NAGase C. The latter was purified to homogeneity with 600-fold enrichment and a yield of 17%. The molecular mass was 150 kDa. NAGase B showed characteristics of a glycoprotein due to affinity towards concanavalin A sepharose, while NAGase C did not. Highly specific polyclonal antibodies to NAGase C [anti-(E. superba-NAGase C)-IgG] showed only negligible cross-reactivity with NAGase B isoforms. A comparison with the Northern krill, Meganyctiphanes norvegica, revealed a corresponding chromatographic pattern with two main activity peaks, for differentiation named NAGase II and NAGase III. Application of the antibody on M. norvegica revealed a high specificity toward NAGase III and a low cross-reactivity with NAGase II. First indication is given that the two forms are no isoenzymes in a strict sense but instead may have different functions in the metabolism of krill.
为了研究几丁质分解酶N-乙酰-β-D-氨基葡萄糖苷酶（NAGase，EC 3.2.1.52）的两种形式在温度适应过程中的潜在作用，已从南极磷虾（Euphausia superba）中分离出这两种形式。开发了一种色谱方法，可将这两种酶形式（分别命名为NAGase B和NAGase C）完全分离。后者被纯化至同质，富集了600倍，产率为17%。分子量为150 kDa。由于对伴刀豆球蛋白A琼脂糖有亲和力，NAGase B表现出糖蛋白的特征，而NAGase C则没有。针对NAGase C的高度特异性多克隆抗体[抗-（E. superba-NAGase C）-IgG]与NAGase B同工型的交叉反应性可忽略不计。与北方磷虾（Meganyctiphanes norvegica）的比较显示，有一个相应的色谱模式，有两个主要活性峰，分别命名为NAGase II和NAGase III。将该抗体应用于北方磷虾，显示对NAGase III具有高度特异性，与NAGase II的交叉反应性较低。初步迹象表明，这两种形式严格意义上不是同工酶，而是可能在磷虾的代谢中具有不同功能。
