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Serious Chemistry | Thread: Bookmark Forum index Next | |
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Posts 58 - 63 of 63 | Subject: Biosynth (homebrewing E) | Page: Previous First All | | |
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| roger2003 (Stranger) 01-12-03 01:23 No 397227 |
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Industrial Biotransformation: ... | Bookmark Reply | |||||
Industrial Biotransformation: http://www.ct.utwente.nl/ipp/docs/Papers http://imb.usal.es/castellano/personales roger2003 |
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| placebo (not quite as irritable lately) 01-24-03 09:23 No 400937  |
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I apoligise if any of this has already been... | Bookmark Reply | |||||
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 production Prof 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. .gif) http://www.biotech.unsw.edu.au/research2 http://www.iupac.org/publications/ci/199 Here is the details from this one... Environmental biotechnology The 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. Intelligence is not the recall of knowledge, but the ability to use it. (Rainman was a retard) |
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| placebo (not quite as irritable lately) 01-24-03 09:40 No 400943 |
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From http://www.swsbm.com/Abstracts/Ephedra-AB.... | Bookmark Reply | |||||
From http://www.swsbm.com/Abstracts/Ephedra-A *****ADVANCES IN BIOCHEMICAL ENGINEERING/BIOTECHNOLOGY***** Rogers PL Shin HS Wang B Biotransformation for L-ephedrine production. In: Adv Biochem Eng Biotechnol (1997) 56:33-59 ISSN: 0724-6145 L-ephedrine is widely used in pharmaceutical preparations as a decongestant and anti-asthmatic compound. One of the key intermediates in its production is L-phenylacetylcarbinol (L-PAC) which can be obtained either from plants (Ephedra sp.), chemical synthesis involving resolution of a racemic mixture, or by biotransformation of benzaldehyde using various yeasts. In the present review, recent significant improvements in the microbial biotransformation are assessed for both fed-batch and continuous processes using free and immobilised yeasts. From previous fed-batch culture data, maximal levels of L-PAC of 10-12 gl-1 were reported with yields of 55-60% theoretical based on benzaldehyde. However, recently concentrations of more than 22 gl-1 have been obtained using a wild-type strain of Candida utilis. This has been achieved through optimal control of yeast metabolism (via microprocessor control of the respiratory quotient, RQ) in order to enhance substrate pyruvate production and induce pyruvate decarboxylase (PDC) activity. Processes involving purified PDC have also been evaluated and it has been demonstrated that L-PAC levels up to 28 gl-1 can be obtained with yields of 90-95% theoretical based on the benzaldehyde added. In the review the advantages and disadvantages of the various strategies for the microbial and enzymatic production of L-PAC are compared. In view of the increasing interest in microbial biotransformations, L- PAC production provides an interesting example of enhancement through on-line control of a process involving both toxic substrate (benzaldehyde) and end-product (L-PAC, benzyl alcohol) inhibition. Registry Numbers: EC 4.1.1.1 (Pyruvate Decarboxylase) 100-52-7 (benzaldehyde) 299-42-3 (Ephedrine) 67-64-1 (Acetone) 90-63-1 (1-hydroxy-1-phenyl-2-propanone) Taken from http://www.ephedra.nu/engels/ Also found same info mirrored here... http://www.r00t-access.org/texts/ephedri First site is interesting site devoted completely to ephedrine. Synthesis of ephedrine ====================== Actively fermenting yeast transforms benzaldehyde into L-phenylacetylcarbinol (L-PAC), which can be reductively aminated to afford ephedrine or phenypropa-nolamine (depending on the amine used) ---------------------------------------- Title: ISOLATION, ANALYSIS, AND SYNTHESIS OF EPHEDRINE AND ITS DERIVATIVES Abstract: A review is given of methods for the isolation, quantitative determination, and modification of the ephedrine alkaloids, and advances in this field of natural compound chemistry. Author: Gazaliev, A. N.; Zhurinov, M. Zh.; Fazylov, S. D.; Balitskii, S. N. Reference: Chem.Nat.Compd.(Engl.Transl.), 25, 3, 1989, 261-271 ---------------------------------------- Title: The biosynthesis of ephedrine Abstract: It is shown by 13C nuclear magnetic resonance spectroscopy that the labelled C2 fragment of <2,3-13C2>pyruvic acid is transferred intact into the C-methyl group and the adjacent carbon atom of the Ephedra alkaloids, norephedrine, ephedrine, norpseudoephedrine, and pseudoephedrine, in growing plants of Ephedra gerardiana.This finding serves to identify pyruvate as the elusive precursor of the aliphatic C2 terminus of the skeleton of the alkaloids.In earlier experiments with 14C-labelled substrates, label from <3-14C>pyruvic acid was incorporated mainly, but not exclusively, into the C-methyl group of ephedrine, and label from <2-14C>pyruvate was incorporated similarly into the carbon atom adjacent to the C-methyl group.A C6-C1 unit related to benzaldehyde or benzoic acid has long been known to generate the benzylic fragment of the carbon skeleton of the Ephedra alkaloids.It is likely that the carbon skeleton of ephedrine is generated from pyruvate and either benzaldehyde or benzoic acid, by a reaction analogous to the formation of acetoin or diacetyl from pyruvate and acetaldehyde or acetic acid, respectively.Key words: biosynthesis of ephedrine, Ephedra alkaloids, 13C NMR spectra, ephedrine, biosynthesis of pyruvic acid, incorporation into ephedrine 13C NMR spectra. Grue-Sorensen et al, Can.J.Chem., EN, 67, 1989, 998-1009 ---------------------------------------- Stereoselectrive Syntheses of Ephedrine and Related 2-Aminoalcohols of High Optical Purity from Protected Cyanohydrins Abstract: Ephedrine and related optically active b-aminoalcohols can be prepared by zinc borohydride reduction of aryl O-protected magnesium imines and aryl a-hydroxyimimes which in turn are readily available from optically active cyanohydrins. Jackson et al, Tetrahedron Lett., 31, 10, 1990, 1447-1450 ---------------------------------------- Title: SYNTHESIS OF EPHEDRINE (DIALKYL PHOSPHOROTHIOATE)S. CRYSTALLOGRAPHIC STRUCTURE OF EPHEDRINE (DIETHYL PHOSPHOROTHIOATE) Abstract: The synthesis of ephedrine (dialkyl phosphorothioate)s has been effected.The method of their preparation and their properties are described.The IR and PMR spectra of ephedrine (dialkyl phosphorothioate)s and some results of an x-ray structural investigation of the spatial structure of ephedrine (diethylphosphorothioate) are given. ---------------------------------------- Methods for Biocatalyst Screening [url]http://www.google.com/search?q=cach Again, sorry if some is redundant, I tried to check everything back thru this thread, but it's a bit of a mission. It seems as though the limited amount of info on the net regarding this matter is mostly the same stuff. Intelligence is not the recall of knowledge, but the ability to use it. (Rainman was a retard) |
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| Organikum (Hive Addict) 01-24-03 19:44 No 401069  |
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The most effective way to L-PAC | Bookmark Reply | |||||
The most effective way to do this biotransformation is: benzaldehyde + acetaldehyde + molasses + brewers wort + some salts whereby: benzaldehyde from toluene and/or benzylalcohol acetaldehyde from ethylalcohol Yields up to 70% on benzaldehyde. But who minds if less, as the benzaldehyde not converted to L-PAC gets converted to benzylalcohol which can be oxidized to benzaldehyde again quite easily. Without acetaldehyde yields are cut by half. Java has linked to the post with the writeup, if some is interested in the details. To the writeup is to add that it is not necessary to distill the L-PAC as written, but the extract from the fermentation broth can be reductive animated as is. No strong vacuum pump necessary! Tested with Al/Hg reductive alkylation. The method is unbeaten by now (except by pure separated enzymes, >90% but extreme expensive). Great work Placebo! Quite comprehensive, real good work. ORG |
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| placebo (not quite as irritable lately) 01-24-03 22:26 No 401090 |
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Re: I will be happy if I would get the L-PAC... | Bookmark Reply | |||||
Intelligence is not the recall of knowledge, but the ability to use it. (Rainman was a retard) |
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| Organikum (Hive Addict) 01-25-03 01:24 No 401113 |
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What Rhodium sent me | Bookmark Reply | |||||
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