海藻酸钠固定化S-腺苷甲硫氨酸合成酶的制备及其性质研究

Preparation and Properties of Sodium Alginate-Immobilized S-Adenosylmethionine Synthetase

研究了以海藻酸钠包埋法制备固定化S-腺苷甲硫氨酸(SAM)合成酶的条件,并考察了固定化酶的酶学性质。结果表明,最适固定化条件为:海藻酸钠质量分数3%、CaCl2质量分数4%、SAM合成酶加量(以每克海藻酸钠计)75mg、固定化时间30min,在此条件下,固定化酶活力回收率达到42%。固定化酶热稳定性较好,在50℃下保温5h仍保留69%的酶活力,而游离酶则完全失活;固定化酶在碱性条件下的稳定性较好,在pH值7.5～9.0的缓冲溶液中4℃下保温10h仍保留84%以上的酶活力;将固定化酶用于SAM的合成,连续反应5批次后,仍保留82%的酶活力。

The immobilization of S-adenosylmethionine（SAM） synthetase by embedding in sodium alginate was studied and properties of the immobilized enzyme were investigated. The results showed the optimal immo- bilization conditions were as follows：mass fraction of sodium alginate was 3 % ,mass fraction of calcium chloride was 4%,SAM synthetase amount was 75 mg,immobilization time was 30 rain. Under the optimum conditions, the activity recovery rate of the immobilized enzyme reached 42M. The immobilized enzyme showed a good ther- mal stability compared with the free enzyme. After incubated at 50 ＊C for 5 h,the immobilized enzyme main- tained 69 % of the original activity while the free enzyme lost all. The immobilized enzyme showed a good stabil- ity in alkaline solution,it still kept more than 84 - of the original activity when incubated in the buffer solution with pH value of 7. 5-9.0 at 4 ℃ for 10 h. When employed to synthesize SAM,the immobilized enzyme main- tained 82 % of the original activity after consecutive use for 5 times.