By leveraging enzyme evolution technologies, the enantioselectivity of a KetoREDuctase (KRED) towards the nearly spatially symmetrical ketone tetrahydrothiophene-3-one was increased from 63% ee to 99.3% ee. The biocatalytic process gives (R)-tetrahydrothiophene-3-ol in one step from a commodity chemical and supplants the original multistep hazardous processes starting from the chiral pool. The biocatalytic process has been successfully scaled to 100 kg.
Two distantly linked clusters of genes on the Salmonella typhimurium phage P22 chromosome are involved in the control of lysogeny and superinfection immunity. One cluster consists of genes cl, ~2, and ~3, which are primarily responsible for the establishment and maintenance of lysogeny. It has been proposed that the second cluster consists of three loci which are responsible for the synthesis and control of an antirepressor substance which overcomes the repression mediated by the c2 gene product. This paper reports the isolation of mutants in a locus designated "ant" having characteristics expected of antirepressor mutants. Evidence is presented that the other loci in this second immunity region, mnt and &rA, control the expression of the ant gene as repressor and promoter/operator, respectively. The interactions of these three loci with each other and with the other immunity region are discussed.
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