Hong V N, Beauregard G, Potier M, Bélisle M, Mameli L, Gatti R, Durand P
Biochim Biophys Acta. 1980 Dec 4;616(2):259-70. doi: 10.1016/0005-2744(80)90143-6.
At least two components of neuraminidase (acylneuraminyl hydrolase, EC 3.2.1.18) can be distinguished in human leucocytes on the basis of pH optimum, thermolability at 30 degrees C and the effect of the detergent octyl-beta-D-glucoside. With 4-methylumbelliferyl-alpha-D-N-acetylneuraminate as substrate, the A component has a pH optimum of 5.0, is labile at 30 degrees C and is unaffected by 0.2 M octyl-beta-glucoside. The B component has a pH optimum of 4.0-4.2, is stable at 30 degrees C but loses most of its activity in the presence of 0.2 M octyl-beta-glucoside. Both A and B components are membrane-bound but only the A component is solubilized by octyl-beta-glucoside in an active form. Molecular weights of neuraminidases by gamma-ray radiation inactivation (a method that does not require solubilization of the enzyme) were found to be 240 000 +/- 19 000 for the B component, 203 000 +/- 17 000 for the A component and 238 000 +/- 8000 for the octyl-beta-glucoside-solubilized A component. Gel filtration of soluble A component on Sephacryl S-300, in the presence of octyl-beta-glucoside, showed a single peak of activity eluted at or near the void volume suggesting that the enzyme is still in an aggregated form. Profound deficiency of neuraminidase activity was found for both A and B components in leucocytes of patients affected with sialidoses type 1 and 2 (less than 15% normal) and intermediate activity in obligate heterozygotes. These results suggest that the A and B components of leucocyte neuraminidase are closely related from the genetic point of view and that rapid diagnosis of sialidoses can be done by fluorimetric assay of neuraminidase in leucocytes.
根据最适pH值、30℃时的热稳定性以及去污剂辛基-β-D-葡萄糖苷的影响，在人白细胞中可区分出神经氨酸酶（酰基神经氨酸水解酶，EC 3.2.1.18）的至少两种组分。以4-甲基伞形酮基-α-D-N-乙酰神经氨酸为底物时，A组分的最适pH值为5.0，在30℃时不稳定，且不受0.2M辛基-β-葡萄糖苷的影响。B组分的最适pH值为4.0 - 4.2，在30℃时稳定，但在0.2M辛基-β-葡萄糖苷存在下大部分活性丧失。A和B组分均与膜结合，但只有A组分能被辛基-β-葡萄糖苷以活性形式溶解。通过γ射线辐射失活法（一种不需要酶溶解的方法）测定的神经氨酸酶分子量，B组分为240 000±19 000，A组分为203 000±17 000，辛基-β-葡萄糖苷溶解的A组分为238 000±8000。在辛基-β-葡萄糖苷存在下，将可溶性A组分在Sephacryl S - 300上进行凝胶过滤，结果显示在空体积或其附近洗脱的单一活性峰，表明该酶仍处于聚集形式。在1型和2型唾液酸沉积症患者的白细胞中，A和B组分的神经氨酸酶活性均严重缺乏（低于正常水平的15%），而杂合子携带者的活性处于中等水平。这些结果表明，从遗传学角度来看，白细胞神经氨酸酶的A和B组分密切相关，并且可以通过荧光法测定白细胞中的神经氨酸酶来快速诊断唾液酸沉积症。
