INFLUENZA-VIRUS SIALIDASE - EFFECT OF CALCIUM ON STEADY-STATE KINETIC-PARAMETERS
INFLUENZA-VIRUS SIALIDASE - EFFECT OF CALCIUM ON STEADY-STATE KINETIC-PARAMETERS
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DOI：
10.1016/0167-4838(91)90526-6
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发表时间：
1991-03-08
期刊：
影响因子：
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通讯作者：
VONITZSTEIN, M
中科院分区：
文献类型：
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作者：
CHONG, AKJ;PEGG, MS;VONITZSTEIN, M
Ca 2+增加流感病毒（A/Tokyo/3/67）唾液酸酶的初始活性速率。 增加离子强度也激活流感病毒唾液酸酶。 当控制离子强度时，观察到较小但仍然显著的Ca 2+效应，V（max）/K（m）从0.8增加。10（5）至1.4。10（5）M ~（-1）s ~（-1），V（max）由6.3 s ~（-1）增加到9.5 s ~（-1）。 竞争性抑制剂2，3-双氧-2-脱氧-N-乙酰神经氨酸的K（i）从2.7降低。10（-6）至1.15。10（-6）M。 结果表明，Ca ~（2+）对V（max）/K（m）有一定的影响，使底物与酶的相互作用速率增加。 Ca 2 +-唾液酸酶复合物的K（d-app）为2 mM。除Mg 2+的行为类似于Ca 2+外，其他一价和二价阳离子对唾液酸酶动力学几乎没有特异性影响。 流感病毒唾液酸酶的一系列亚型的序列分析支持的建议，Ca 2+结合在亚基界面传输的构象变化的酶的活性位点。 Ca 2+激活可能在从宿主细胞表面释放新合成的病毒体期间在开启唾液酸酶活性中具有生理作用。
Ca2+ increases the initial rate of activity of sialidase from influenza virus (A/Tokyo/3/67). Increasing ionic strength also activates influenza virus sialidase. When ionic strength is controlled, smaller but still significant Ca2+ effects are observed, with V(max)/K(m) increased from 0.8 . 10(5) to 1.4 . 10(5) M-1 s-1 and V(max) increased from 6.3 to 9.5 s-1 by saturating Ca2+. The K(i) of the competitive inhibitor 2,3-dehydro-2-deoxy-N-acetylneuraminic acid was decreased from 2.7 . 10(-6) to 1.15 . 10(-6) M after the addition of saturating Ca2+. The data show that Ca2+ exerts a specific effect on V(max)/K(m), leading to an increased rate of interaction of substrate with the enzyme. The K(d-app) for the Ca2+-sialidase complex is 2 mM. Except for Mg2+ which behaves similarly to Ca2+, other mono- and divalent cations have little specific effect on sialidase kinetics. Sequence analysis of a range of subtypes of sialidases from influenza virus supports the proposal that Ca2+ binds at the subunit interface transmitting a conformational change to the enzyme active site. Ca2+ activation may have a physiological role in switching on sialidase activity during the release of newly synthesised virions from the host cell surface.