I apologise if any of this has already been posted....
Here is the relevant bits from the SchmidetalEnzymes2002.pdf in the above post... The flavoenzyme tryptophan 7-halogenase has been evaluated for selective chlorination of tryptophan and indole derivatives. The reaction is thought to proceed via the formation of an epoxide and ring-opening to a chlorohydrin followed by dehydration. Glaxo Wellcome Research and Development reported on the use of nucleoside oxidase. The enzyme was found to have a very broad substrate spectrum towards unnatural nucleosides.
Immobilization of the oxidase directly from crude extracts onto Eupergit-C resulted in stabilization of its activity, which also allowed reuse of the enzyme and an easy scale-up of the reaction. An interesting carbon–carbon bond formation reaction was reported for the preparation of (R)-phenylacetylcarbinol by carboligation of pyruvate and benzaldehyde using various pyruvate decarboxylases. Continuous production of (R)-phenylacetylcarbinol from acetaldehyde and benzaldehyde could be achieved using a mutant of pyruvate decarboxylase from Zymomonas mobilis in an enzyme membrane reactor (EMR) with space-time yields of 81g L–1 d–1.
Widespread application of enzymes in the chemical industry will depend on the ability to couple enzymatic and chemical steps. Chemoenzymatic reaction sequences profit from the high technical development level of both chemical and enzymatic reactions. DSM uses well-established amidase catalysis to produce enantiopure Cá-tetrasubstituted á-amino acids containing terminal double bonds that react to cyclic oligopeptides by Grubbs olefin metathesis. Lonza uses a sequence of nitrile hydratase catalysis, chemical hydrogenation, and amidase-catalyzed reactions to obtain enantiopure pipecolic and piperazine carboxylic acids from aromatic nitrile precursors. Making biocatalysis compatible with chemical multistep synthesis is one of the important future challenges for this new technology.
Conclusions
Today, applications of enzymes in the chemical industry are already well established and, given the current developments, the number of biocatalytic processes will continue to increase rapidly. The first hurdle, confidence in the new technology, has been taken and as more and more processes, technology and infrastructure are implemented, efforts in biocatalytic research and development will also increase. This will allow the discovery and application of new enzymes and biological counterparts for traditional chemical reactions and will facilitate the integration of enzymatic steps in chemical multistep syntheses.
Biotransformation processes for L-PAC productionProf Peter Rogers
Biotransformation processes involving both yeast (Candida utilis) and pyruvate decarboxylase (PDC) are being evaluated for the production of L-phenylacetylcarbinol (L-PAC) from substrates benzaldehyde and pyruvate. L-PAC is an intermediate in the production of the decongestant and antiasthmatic pharmaceuticals, ephedrine and pseudoephedrine. Kinetic models for the process are under development together with a computer-based optimal substrate feeding profile for benzaldehyde.
Funding sources: Commercial (ICI 1994-6; other 1997-9)
Student involvement: One Postdoctoral Research Fellow and two PhD students, MAppSc and Honours students
Recent publications:
Shin, H.S. and Rogers, P.L. (1996) Production of L-PAC from benzaldehyde using partially purified pyruvate decarboxylase (PDC). Biotechnol. Bioeng. 49, 52-62.
Shin, H.S. and Rogers, P.L. (1996) Kinetic evaluation of biotransformation of benzaldehyde to L-PAC by immobilized pyruvate decarboxylase. Biotechnol. Bioeng. 49, 429-436.
Rogers, P.L., Shin, H.S. and Wang, B. (1997) Biotransformation for L-ephredrine production. Adv. Biochem. Eng. 56, 33-60.
Liew, M.K.H., Fane, A.G. and Rogers, P.L. (1997) Fouling effects of yeast culture with antifoam agents on microfilters. Biotechnol. Bioeng. 53, 10-16.
Liew, M.K.H., Fane, A.G. and Rogers, P.L. (1997) Fouling of microfiltration membranes by broth-free antifoam agents. Biotechnol. Bioeng. 56, 89-98.
http://www.biotech.unsw.edu.au/research2.htm
http://www.iupac.org/publications/ci/1997/november/review.pdf
Here is the details from this one...
Environmental biotechnologyThe November issue also contains selected proceedings of an International Conference on Environmental Biotechnology ‘96 held in Palmerston North, New Zealand, 1–4 September 1996. The published conference papers offer a wide-ranging analysis of the potential of biotechnology to waste treatment, specific perspectives on environmental damage and remediation, industrial research on pollutant mitigation, research into the area of upflow anaerobic sludge blanket reactors, the biological treatment of food industry wastes and two examples of cleaner technology for developments from the pharmaceutical and paper industries. The cleaner technology examples included production of phenylacetylcarbinol (PAC) and production of phenylacetylcarbinol by yeast through productivity improvements and waste minimisation. LPhenylacetylcarbinol is a precursor for the synthesis of L-ephedrine and D-pseudoephedrine, two pharmaceuticals with nasal decongestant properties. LPhenylacetylcarbinol is generated biologically through the pyruvate decarboxylase-mediated condensation of added benzaldehyde with acetaldehyde generated metabolically from feed stock sugars via pyruvate. Some of the added benzaldehyde is converted through the action of alcohol dehydrogenase(s) to benzyl alcohol, an undesired by-product.
L-Phenylacetylcarbinol extracted from the fermentation broth is converted chemically by hydroamination in the presence of methylamine and hydrogen to L-ephedrine, and then by isomerization to D-pseudoephedrine. Bruce Anderson and colleagues at the Royal Melbourne Institute of Technology present a dual approach strategy to enhance the ratio of product to by-product generated and to minimize the waste treatment burden of the spent fermentation broth. He explains that benzaldehyde delivery to the fermentation has been modified to ensure that sufficient raw material is available, together with pyruvate, during peak periods of pyruvate decarboxylase activity, and that benzaldehyde is less available during periods of high alcohol dehydrogenase activity. The inorganic content of the spent fermentation broth has been reduced substantially by the partial substitution of raw sugar for molasses in the medium, with a reduction of molasses content by 60% resulting in an increase of phenylacetylcarbinol production.
Further work on the optimization of the concentration of carbohydrate, nitrogen and phosphate in the fermentation has been conducted and has led, he claims, to further productivity increases, together with reduced waste generation, resulting in an L-phenylacetylcarbinol process which is considerably ‘cleaner’ than the parent process.
Taken from some guy's resume I found in a search engine...
Head, Food & Fermentation Technology Division.The project dealt with the biotransformation of benzaldehyde to L- phenyl acetyl carbinol (synthon for various drugs) using yeast isolate. Various aspects like standardization of the method of analysis, purification and identification of product & byproducts of the biotransformation using various techniques were standardised. Using yeast isolate, various process parameters for increasing yield of the product and reusability of the biocatalyst were studied. A novel immobilization method for the aforesaid biotransformation was standardised and the process parameters using immobilized cell system studied. The mass transfer coefficient, power consumption and hold up in a stirred tank reactor with a dual impeller system were studied for the growth and biotransformation medium and were compared with those for air-water system.
After establishing the correlation between these operating parameters, a scaling up of this biotransformation to 5 L was achieved in a systematic manner. Work was also carried out on the synthesis of various chiral compounds using a combination of chemical synthesis and biotransformation using Rhizopus arrhizus.
to be continued.
