Study on Immobilization of S-Adenosylmethionine Synthetase on Amino Resin

S-Adenosylmethionine(SAM)synthetase was immobilized on amino resin.The optimal immobilization conditions and the properties of the immobilized enzyme were investigated.The optimal immobilization conditions were as follows:the volume fraction of glutaraldehyde was 5%,the dosage of SAM synthetase was 20mg·g-1,the immobilization time was 5h.Under these conditions,the activity of the immobilized SAM synthetase was 476.8U·g-1 with the activity recovery rate of 74.5%.Additionally,compared with the free SAM synthetase,the stability of immobilized SAM synthetase was improved significantly.After incubation at 50 ℃for 5h,the immobilized SAM synthetase maintained 61.2% of the original activity while the free SAM synthetase was completely inactivated.The stability of immobilized SAM synthetase in buffer solution at pH value6.0~6.5,8.0~9.5was also improved.The immobilized SAM synthetase remained 86.3% activity after ten times repeated operations.Moreover,the immobilized SAM synthetase maintained 81.4%of the original activity when it was stored at 4℃for 30 d.The Michaelis constant of the immobilized SAM synthetase was 0.14mmol·L-1(KATPm)and 0.28mmol·L-1(KLm-Met).