从麦芽根中分离得到了5′-磷酸二酯酶,采用戊二醛为交联剂,将该酶固定到壳聚糖上,用于酵母RNA的催化水解,以制备5′-核苷酸.研究了酶固定化反应的影响因素,在最适条件下,酶活回收率可达53.6%.进一步研究了固定化5′-磷酸二酯酶的酶学性质,测得固定化酶的米氏常数Km为15.38 mg/mL(以RNA为底物),固定化酶催化水解RNA的最适温度为75℃,最适pH值为5.5,实验发现固定化5′-磷酸二酯酶具有更好的耐热性和更高的纯度.%5′-phosphodiesterase (5′-PDE) was separated from barley roots and the immobilization of this enzyme on chitosan was studied using glutaric dialdehyde as a cross-linking agent. The immobilized enzyme can be applied to the hydrolysis of yeast RNA to yield 5′-nucleotides. The results showed that an enzyme recovery of 53.6 % was achieved when the reaction took place at the optimum condition. Further studies indicated that Michaelis constant (Km) for the immobilized 5′-PDE was 15.38 mg/mL with yeast RNA as the substrate, and the immobilized enzyme had an optimum pH 5.5, and optimum temperature 75℃ for the hydrolysis of RNA. The results also showed that the immobilized enzyme was purer, and had a better thermostability than the free 5′-PDE.
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