重组人铜锌SOD的部分理化性质研究

对rhCu,Zn-SOD进行SDS-PAGE测定该SOD的亚基分子质量为19 ku,该酶对热稳定,在pH5左右的活力最高,对乙腈、EDTA等抑制剂敏感,但是对SDS、尿素等变性剂表现出很好的稳定性。对该酶进行光谱分析表明,在265nm和673nm具有吸收峰,原子吸收光谱分析表明每分子SOD含有2个铜原子和2个锌原子,ESR表明铜原子价态为2价。可认为该重组酶与天然Cu,Zn-SOD在理化性质和结构上基本相同。

Reductive amination of ketones with ammonium catalyzed by a newly identified Brevibacterium epidermidis strain for the synthesis of(S)-chiral amines

The asymmetric reductive amination of achiral ketones with ammonia is a particularly attractive reaction for the synthesis of chiral amines.Although several engineered amine dehydrogenases have been developed by protein engineering for the asymmetric reductive amination of ketones,they all display(R)‐stereoselectivity.To date,there is no report of an(S)‐stereoselective biocatalyst for this reaction.Herein,a microorganism named Brevibacterium epidermidis ECU1015 that catalyzes the(S)‐selective reductive amination of ketones with ammonium has been successfully isolated from soil.Using B.epidermidis ECU1015 as the catalyst,the asymmetric reductive amination of a set of phenylacetone derivatives was successfully carried out,yielding the corresponding(S)‐chiral amines with moderate conversion and>99%enantiomeric excess.