Sulfoquinovose (6-deoxy-6-sulfo-D-glucopyranose), formed by the hydrolysis of the plant sulfolipid, is a major component of the biological sulfur cycle. However, pathways for its catabolism are poorly delineated. We examined the hypothesis that mineralization of sulfoquinovose to inorganic sulfate is initiated by reactions of the glycolytic and/or Entner-Doudoroff pathways in bacteria. Metabolites of [U-13 C]sulfoquinovose were identified by 13 C-nuclear magnetic resonance (NMR) in strains of Klebsiella and Agrobacterium previously isolated for their ability to utilize sulfoquinovose as a sole source of carbon and energy for growth, and cell extracts were analyzed for enzymes diagnostic for the respective pathways. Klebsiella sp. strain ABR11 grew rapidly on sulfoquinovose, with major accumulations of sulfopropandiol (2,3-dihydroxypropanesulfonate) but no detectable release of sulfate. Later, when sulfoquinovose was exhausted and growth was very slow, sulfopropandiol disappeared and inorganic sulfate and small amounts of sulfolactate (2-hydroxy-3-sulfopropionate) were formed. In Agrobacterium sp. strain ABR2, growth and sulfoquinovose disappearance were again coincident, though slower than that in Klebsiella sp. Release of sulfate was still late but was faster than that in Klebsiella sp., and no metabolites were detected by 13 C-NMR. Extracts of both strains grown on sulfoquinovose contained phosphofructokinase activities that remained unchanged when fructose 6-phosphate was replaced in the assay mixture with either glucose 6-phosphate or sulfoquinovose. The results were consistent with the operation of the Embden-Meyerhoff-Parnas (glycolysis) pathway for catabolism of sulfoquinovose. Extracts of Klebsiella but not Agrobacterium also contained an NAD ؉ -dependent sulfoquinovose dehydrogenase activity, indicating that the Entner-Doudoroff pathway might also contribute to catabolism of sulfoquinovose.
A template-based mnemonic has been developed for the enzyme monoamine oxidase from Aspergillus niger and has been used to successfully identify the alkaloid (+/-)-crispine A as a target for chemo-enzymatic deracemisation yielding the biologically active (R)-enantiomer in 97% e.e.
Recent reports show that contrary to common perception, branched alkyl sulfate surfactants are readily biodegradable in standard biodegradability tests. We report here the isolation of bacteria capable of biodegrading 2-butyloctyl sulfate and the identification of novel enzymes that initiate the process. Enrichment culturing from activated sewage sludge yielded several strains capable of growth on 2-butyloctyl sulfate. Of these, two were selected for further study and identified as members of the genus Pseudomonas. Strain AE-A was able to utilize either sodium dodecyl sulfate (SDS) or 2-butyloctyl sulfate as a carbon and energy source for growth, but strain AE-D utilized only the latter. Depending on growth conditions, strain AE-A produced up to three alkylsulfatases, as shown by polyacrylamide gel electrophoresis zymography. Growth on either SDS or 2-butyloctyl sulfate or in nutrient broth produced an apparently constitutive, nonspecific primary alkylsulfatase, AP1, weakly active on SDS and on 2-butyloctyl sulfate. Growth on 2-butyloctyl sulfate produced a second enzyme, AP2, active on 2-butyloctyl sulfate but not on SDS, and growth on SDS produced a third enzyme, AP3, active on SDS but not on 2-butyloctyl sulfate. In contrast, strain AE-D, when grown on 2-butyloctyl sulfate (no growth on SDS), produced a single enzyme, DP1, active on 2-butyloctyl sulfate but not on SDS. DP1 was not produced in broth cultures. DP1 was induced when residual 2-butyloctyl sulfate was present in the growth medium, but the enzyme disappeared when the substrate was exhausted. Gas chromatographic analysis of products of incubating 2-butyloctyl sulfate with DP1 in gels revealed the formation of 2-butyloctanol, showing the enzyme to be a true sulfatase. In contrast, Pseudomonas sp. strain C12B, well known for its ability to degrade linear SDS, was unable to grow on 2-butyloctyl sulfate, and its alkylsulfatases responsible for initiating the degradation of SDS by releasing the parent alcohol exhibited no hydrolytic activity on 2-butyloctyl sulfate. DP1 and the analogous AP2 are thus new alkylsulfatase enzymes with novel specificity toward 2-butyloctyl sulfate.Synthetic surfactants are components of a variety of household and industrial detergent formulations. Other industrial applications include paints, textiles and fabrics, oil-spill dispersants, concrete, paper, lubricants, and many others (14,15,26). In 1990, world production of synthetic surfactants was 7 megatonnes (Mt) per annum, of which 5.3 Mt came from the United States, the European Union, and Japan (12). Of this part, 1.74 Mt per annum was anionic surfactant, a significant quantity which reflects the high demand for this type of surfactant. The anionic surfactant group embraces a range of compounds distinguished on the basis of chemical structure and includes primary alkyl sulfates, such as sodium dodecyl sulfate (SDS), and linear secondary alkyl sulfates, such as dodecyl 2-sulfate. Synthetic primary alkyl sulfates are based on feedstocks derived from long-chain olefins by us...
Five bacterial strains capable of using sulphoquinovose (6-deoxy-6-sulpho-D-glucopyranose) as a sole source of carbon have been isolated and partially characterized.
Previously, we reported a general method for the chemo-enzymatic deracemization of primary, 1 secondary 2 and tertiary 3 amines in high yield and enantiomeric excess. The deracemization process involves a two-step, one-pot reaction and employs an enantioselective amine oxidase (MAO-N) in combination with a nonselective chemical reducing agent (Figure 11.1). We have further demonstrated the utility of this variant enzyme by way of the asymmetric synthesis of the natural product (þ)-crispine A in 97 % ee. 4 The previously reported MAO-N-D5 variant, which contains five important mutations (Ile246Met/Asn336Ser/Met348Lys/ Thr384Asn/Asp385Ser) was used; its preparation has been described previously. 5,6 R 3 R 4 N R 3 R 4 N R 3 R 4 N + NH 3 :BH 3 enantio selective amine oxidase R 1 R 2 R 1 R 2 R 1 R 2 (S) (R) Figure 11.1 Enzymatic deracemization of racemic amines via a two-step, one-pot process utilizing an enantioselective amine oxidase in combination with ammonia-borane. Practical Methods for Biocatalysis and BiotransformationsEdited
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