918-44-5Relevant articles and documents
Improving the acidic stability of Staphylococcus aureus α-acetolactate decarboxylase in Bacillus subtilis by changing basic residues to acidic residues
Zhang, Xian,Rao, Zhiming,Li, Jingjing,Zhou, Junping,Yang, Taowei,Xu, Meijuan,Bao, Teng,Zhao, Xiaojing
, p. 707 - 717 (2015)
The α-acetolactate decarboxylase (ALDC) can reduce diacetyl fleetly to promote mature beer. A safe strain Bacillus subtilis WB600 for high-yield production of ALDC was constructed with the ALDC gene saald from Staphylococcus aureus L3-15. SDS-PAGE analysis revealed that S. aureus α-acetolactate decarboxylase (SaALDC) was successfully expressed in recombinant B. siutilis strain. The enzyme SaALDC was purified using Ni-affinity chromatography and showed a maximum activity at 45 °C and pH 6.0. The values of K m and V max were 17.7 μM and 2.06 mM min-1, respectively. Due to the unstable property of SaALDC at low pH conditions that needed in brewing process, site-directed mutagenesis was proposed for improving the acidic stability of SaALDC. Homology comparative modeling analysis showed that the mutation (K52D) gave rise to the negative-electrostatic potential on the surface of protein while the numbers of hydrogen bonds between the mutation site (N43D) and the around residues increased. Taken together the effect of mutation N43D-K52D, recombinant SaALDCN43D-K52D showed dramatically improved acidic stability with prolonged half-life of 3.5 h (compared to the WT of 1.5 h) at pH 4.0. In a 5-L fermenter, the recombinant B. subtilis strain that could over-express SaALDCN43D-K52D exhibited a high yield of 135.8 U mL-1 of SaALDC activity, about 320 times higher comparing to 0.42 U mL-1 of S. aureus L3-15. This work proposed a strategy for improving the acidic stability of SaALDC in the B. subtilis host.
An artificial enzymatic reaction cascade for a cell-free bio-system based on glycerol
Gao, Chao,Li, Zhong,Zhang, Lijie,Wang, Chao,Li, Kun,Ma, Cuiqing,Xu, Ping
, p. 804 - 807 (2015/03/04)
Conversion of glycerol into high-value products is of significant importance for sustainability in the biofuel industry. In this study, pyruvic acid, a central intermediate needed for the production of versatile biomolecules, was produced from glycerol without the addition of any cofactors by the cell-free bio-system composed of alditol oxidase, dihydroxy acid dehydratase, and catalase. (3R)-Acetoin was then produced at 85.5% of the theoretical yield from glycerol by α-acetolactate synthase and α-acetolactate decarboxylase. Since other biomolecules can also be produced from pyruvic acid, the cell-free bio-system might serve as a versatile bio-production platform, and support the viability of the biofuel economy. This journal is
REACTION OF 1,2,4-TRIMETHYLBENZENE WITH PERACETIC ACID
Kharchuk, V. G.,Kolenko, I. P.,Petrov, L. A.,Gus'kova, L. M.
, p. 2071 - 2078 (2007/10/02)
The oxidation of 1,2,4-trimethylbenzene with peracetic acid leads to the formation of trimethylphenols and hydroquinones, which undergo transformations to the corresponding benzoquinones and products from oxidative cleavage of the ring.The controlling stage of the process is the electrophilic hydroxylation of 1,2,4-trimethylbenzene.
