enhancements of 10(5)-10(8). The efficient hydrolysis of glycosylpyridinium ions by these three inverting glycosidases, the catalytic mechanism of which is unlikely to involve a nucleophile from the enzyme, makes it improbable that the hydrolysis of glycosylpyridinium ions by retaining glycosidases, discovered some years ago, is initiated by addition of a catalytic nucleophilic carboxylate group of the
短小芽孢杆菌的β-
D-木糖苷酶
水解五个β-D-木
吡喃糖基
吡啶鎓离子的kcat值比相同化合物自发
水解的速率大10(8)-10(9)倍。Log(kcat)值与糖苷配基pK(a)的相关性很好[B1g(V)= -0.52,r = 0.99],而log(kcat / Km)的相关性很差[r = 0.77; β1g(V / K)=约-0.6]。Sporotrichum dimorphosporum的(1-> 3)-β-D-
葡聚糖酶
水解4-
溴-2-(β-
D-吡喃葡萄糖基)
异喹啉鎓离子,速率提高10(8)。黑曲霉的淀粉
葡糖苷酶II
水解三个α-
D-吡喃葡萄糖基
吡啶鎓离子,速率提高10(5)-10(8)。这三个反向糖苷酶可有效
水解糖基
吡啶鎓离子,