成团泛菌苯丙氨酸氨基变位酶的热稳定性改造

Thermostability modification of Pantoea agglomerans phenylalanine aminomutase

来源于原核生物成团泛菌(Pantoea agglomerans)的苯丙氨酸氨基变位酶(PaPAM)可催化α-苯丙氨酸转变为药用价值更高的(S)-β-苯丙氨酸,然而其酶活较低,热稳定性较差,限制其工业应用。本研究突变苯丙氨酸氨基变位酶酶活中心上方loop环上的氨基酸及与其相互作用位点的氨基酸,降低loop环的柔性,以期稳定酶活中心的结构,提高酶的热稳定性。筛选得到热稳定性显著提高的突变体I91M,50℃保温1h后,剩余酶活达到83%(野生型酶酶活仅剩余30%左右)。该结果有助于苯丙氨酸氨基变位酶的理论研究和工业应用。

Pantoea agglomerans phenylalanine aminomutase(PaPAM)catalyzes the conversion ofα-phenylalanine to more valuable(S)-β-phenylalanine.However,its low enzyme activity and poor thermal stability limit its industrial application.In order to improve its thermostability and enzyme activity,this study reduced the flexibility of loops above the active center of Pa PAM by mutating amino acids on the loops and amino acids at the interaction site to stabilize the active center structure.A mutant I91M with significantly improved thermostability was screened,which had 83%residual enzyme activity after incubating at 50℃for 1 h,while the activity of wild-type enzyme only had 30%remained.These results are helpful for further studies and industrial applications of PaPAM.