Guillotin Laure, Kim Hyuna, Traore Yasmina, Moreau Philippe, Lafite Pierre, Coquoin Véronique, Nuccio Sylvie, de Vaumas René, Daniellou Richard
Université d'Orléans, CNRS, ICOA, UMR 7311, Rue de Chartres, BP 6759, 45067 Orléans Cedex 2, France.
Extrasynthese, CS 30062, ZI Lyon Nord, Impasse Jacquard, 69727 Genay Cedex, France.
ACS Omega. 2019 Jan 24;4(1):1916-1922. doi: 10.1021/acsomega.8b03186. eCollection 2019 Jan 31.
α-l-Rhamnosidases are catalysts of industrial tremendous interest, but their uses are still somewhat limited by their poor thermal stabilities and selectivities. The thermophilic Rha from was cloned, and the recombinant protein was easily purified to homogeneity to afford 4.5 mg/L culture of biocatalyst. Michaelis-Menten parameters demonstrated it to be fully specific for α-l-rhamnose. Most significantly, Rha demonstrated to have a stronger preference for α(1 → 2) linkage rather than α(1 → 6) linkage when removing rhamnosyl moiety from natural flavonoids. This selectivity was fully explained by the difference of binding of the corresponding substrates in the active site of the protein.
α-L-鼠李糖苷酶是具有巨大工业应用价值的催化剂，但其热稳定性和选择性较差，在一定程度上限制了它们的应用。克隆了来自嗜热菌的鼠李糖苷酶（Rha），重组蛋白易于纯化至同质，每升培养物可获得4.5毫克生物催化剂。米氏参数表明它对α-L-鼠李糖具有完全特异性。最显著的是，当从天然黄酮类化合物中去除鼠李糖基部分时，Rha对α(1→2)键的偏好强于α(1→6)键。蛋白质活性位点中相应底物结合的差异充分解释了这种选择性。
