Wannet W J, Op den Camp H J, Wisselink H W, van der Drift C, Van Griensven L J, Vogels G D
Department of Microbiology, Faculty of Science, University of Nijmegen, Netherlands.
Biochim Biophys Acta. 1998 Sep 16;1425(1):177-88. doi: 10.1016/s0304-4165(98)00066-x.
Trehalose phosphorylase (EC 2.4.1.64) from Agaricus bisporus was purified for the first time from a fungus. This enzyme appears to play a key role in trehalose metabolism in A. bisporus since no trehalase or trehalose synthase activities could be detected in this fungus. Trehalose phosphorylase catalyzes the reversible reaction of degradation (phosphorolysis) and synthesis of trehalose. The native enzyme has a molecular weight of 240 kDa and consists of four identical 61-kDa subunits. The isoelectric point of the enzyme was pH 4.8. The optimum temperature for both enzyme reactions was 30 degrees C. The optimum pH ranges for trehalose degradation and synthesis were 6.0-7.5 and 6.0-7.0, respectively. Trehalose degradation was inhibited by ATP and trehalose analogs, whereas the synthetic activity was inhibited by P(i) (K(i)=2.0 mM). The enzyme was highly specific towards trehalose, P(i), glucose and alpha-glucose-1-phosphate. The stoichiometry of the reaction between trehalose, P(i), glucose and alpha-glucose-1-phosphate was 1:1:1:1 (molar ratio). The K(m) values were 61, 4.7, 24 and 6.3 mM for trehalose, P(i), glucose and alpha-glucose-1-phosphate, respectively. Under physiological conditions, A. bisporus trehalose phosphorylase probably performs both synthesis and degradation of trehalose.
首次从双孢蘑菇中纯化得到了海藻糖磷酸化酶（EC 2.4.1.64），该酶来自一种真菌。由于在这种真菌中未检测到海藻糖酶或海藻糖合酶活性，所以这种酶似乎在双孢蘑菇的海藻糖代谢中起关键作用。海藻糖磷酸化酶催化海藻糖降解（磷酸解）和合成的可逆反应。天然酶的分子量为240 kDa，由四个相同的61-kDa亚基组成。该酶的等电点为pH 4.8。两种酶反应的最适温度均为30℃。海藻糖降解和合成的最适pH范围分别为6.0 - 7.5和6.0 - 7.0。海藻糖降解受到ATP和海藻糖类似物的抑制，而合成活性受到无机磷酸（K(i)=2.0 mM）的抑制。该酶对海藻糖、无机磷酸（P(i)）、葡萄糖和α-葡萄糖-1-磷酸具有高度特异性。海藻糖、无机磷酸（P(i)）、葡萄糖和α-葡萄糖-1-磷酸之间反应的化学计量比为1:1:1:1（摩尔比）。海藻糖、无机磷酸（P(i)）、葡萄糖和α-葡萄糖-1-磷酸的K(m)值分别为61、4.7、24和6.3 mM。在生理条件下，双孢蘑菇海藻糖磷酸化酶可能同时进行海藻糖的合成和降解。
