摘要
丙谷二肽是重要的营养补充剂,α-酰基转移酶(SAET)可催化丙氨酸甲酯与谷氨酰胺合成丙谷二肽。为提高该酶的pH稳定性,本实验以前期获得的SAET-QC01菌株为基础,对该菌株的关键位点A537进行饱和突变,构建了19个突变体。突变体酶学性质表明,有五个突变体的酶活比原始酶提高了10%以上,其中突变酶A537G在pH为5.0~9.0范围内酶活稳定,比原始酶(pH为8.0~8.5)更有利于反应的进行。通过同源建模发现A537位于β-折叠片中,突变后增加了主链-侧链间氢键作用力,周围小于6埃范围内氨基酸作用的数量明显减少,因此提高了其pH稳定性。
Ala-Gln is an important nutritional supplement,andα-acyltransferase(SAET)can catalyze the synthesis of alanine methyl ester and glutamine into Ala-Gln.In order to improve the pH stability of the enzyme,the strain of SAET-QC01 obtained in the previous study was used as a base,saturation and mutations on the key site A537 of SAET-QC01 was performed and 19 mutants were constructed.The enzymatic properties of mutants showed that the enzyme activities of five mutants increased by more than 10%higher compared to the original enzyme,among which the mutant enzyme A537G was stable in the pH range of 5.0~9.0,which was more conducive to the reaction than the original enzyme(pH 8.0~8.5).Homologous modeling showed that A537 was located inβ-sheet.After mutation,the hydrogen bonding force between main chain and side chain increased,and the number of amino acid interactions in the surrounding range of less than 6 angstroms decreased significantly,thus improving its pH stability.
作者
范玉娜
魏金澳
杨静文
张洪斌
胡雪芹
FAN Yuna;WEI Jin’ao;YANG Jingwen;ZHANG Hongbin;HU Xueqin(School of Food and Biological Engineering,Hefei University of Technology,Hefei 230009)
出处
《中国食品添加剂》
CAS
2024年第4期140-146,共7页
China Food Additives
