Progress 11/03/98 to 10/31/03
Outputs
ACETATE BIOSYNTHESIS With regard to the acetate pathway, we have elucidated the structure and function of CO dehydrogenase/acetyl-CoA synthase (CODH/ACS) and the methyltransferase. We have determined which metals are located at the A-cluster of ACS, elucidated the role of the metal centers in ACS, and performed infrared studies of CO binding to CODH/ACS. We also have developed a better understanding of the balance of carbon and electron flow between CODH and ACS, and determined the electronic structure of the A-Cluster of CODH/ACS. We have determined the structure of the radical intermediate in pyruvate ferredoxin oxidoreductase (PFOR). We also completed the crystal structure of the binary complex between MeTr and its substrate, generated mutants of the MeTr, and obtained a crystal structure of one of them. METHANOGENESIS In the methanogenesis project, we have identified intermediates in the methyl-CoM reductase (MCR) reaction mechanism and elucidated several states of
the enzyme-bound cofactor and characterized a state in which the cofactor macrocycle is reduced and another one in which the metal is reduced. We have developed compounds that inhibit methanogenesis at very low (low micromolar) levels and began a collaboration with an Ag Biotech company, PharmAgra, Inc. DEHALOGENATION OF PCBs & RELATED CHLORINATED AROMATICS With regard to the dehalogenase studies, we have heterologously expressed the the B12 and iron-sulfur containing dehalogenase in a soluble form. We also have made major progress in determining the mechanism of regulation of expression of genes involved in PCB metabolism by overexpressing and purifying the DNA binding transcriptional activator CprK and characterizing the mode of DNA binding.
Impacts
Our studies on the Acetate Biosynthesis pathway are having major impact into the fields of enzymology, metallobiochemistry, and anaerobic microbiology in setting paradigms for how methyl transfer reactions and carbon monoxide metabolism reactions occur. The mechanistic studies are very important in solving a long-running controversy about the role of nickel and copper in acetate biosynthesis. These results will impact the bioinorganic community as well as the microbiology community. Our recent results help explain how bacteria make an important biochemical intermediate that is a toxic gas and how they protect their host against the toxic effects. In our Methanogenesis work, we have resolved the controversy about how redox changes in the Ni versus the ligand (an unusual tetrapyrrole called Factor F430) are involved in the mechanism of methane formation. The methanogenesis inhibitors we are developing have the promise of use in animal feed to reduce atmospheric methane
concentrations, which could alleviate the greenhouse effect, and to lower the cost of raising livestock. This work gained significant national attention with articles in most newspapers including USA Today and radio coverage including interviews with Pat Reuter (Viewpoints). In work on anaerobic Dehalogenation, we are uncovering how microbes use toxic halogenatic organics like PCBs in their energy metabolism. One of their primary degradation products is the hydroxylated-PCB. Our results uncover a likely mechanism for their biodegradation and also a potential for detoxification.
Publications
- Seravalli, J., W. Gu, A. Tam, E. Strauss, T.P. Begley, S.P. Cramer, and S.W. Ragsdale. 2003. Functional copper at the acetyl-CoA synthase active site. Proc Natl Acad Sci U S A 100:3689-3694.
- Singh, K., Y.-C. Horng, and S.W. Ragsdale. 2003. Rapid Ligand Exchange in the MCRred1 form of Methyl-Coenzyme M Reductase. J Am Chem Soc 125:2436-2443.
- Dumitru, R., H. Palencia, S.D. Schroeder, B.A. DeMontigny, J.M. Takacs, M.E. Rasche, J.L. Minor, and S.W. Ragsdale. 2003. Targeting Methanopterin Biosynthesis to Inhibit Methanogenesis. Applied and Environmental Microbiology 69:in press.
- Craft, J.L., Y.-C. Horng, S.W. Ragsdale, and T.C. Brunold. 2003. Spectroscopic and Computational Characterization of the Nickel-Containing F430 Cofactor of Methyl-Coenzyme M Reductase. Journal of Biological Inorganic Chemistry:in press.
- Ragsdale, S.W. 2003. Anaerobic one-carbon catalysis, p. 665-695. In I. T. Horvath, E. Iglesia, M. T. Klein, J. A. Lercher, A. J. Russell, and E. I. Stiefel (ed.), Encyclopedia of catalysis, vol. 1. John Wiley and Sons, Inc., New York
- Ragsdale, S.W. 2003. Pyruvate:ferredoxin oxidoreductase and its radical intermediate. Chemical Reviews 103:2333-2346.
- Banerjee, R., and S.W. Ragsdale. 2003. The Many Faces of Vitamin B12: Catalysis by Cobalamin-dependent Enzymes. Ann Rev. Biochem 72:209-247.
- Ragsdale, S.W. 2003. Biochemistry of Methyl-CoM Reductase and Coenzyme F430, p. 205-228. In K. M. Kadish, K. M. Smith, and R. Guilard (ed.), The Porphyrin Handbook, vol. 11. Academic Press, New York
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Progress 10/01/01 to 09/30/02
Outputs
ACETATE BIOSYNTHESIS We determined the structure of CO dehydrogenase/acetyl-CoA synthase (CODH/ACS) at 2.2 angstrom resolution. The structure revealed an unexpected metal, copper, in the active site. A reaction intermediate (acetyl-copper) was also trapped in the crystal structure. Furthermore, the structure revealed how the toxic gas, carbon monoxide, which is generated at the CODH active site, is directed to the ACS active site through a 140 angstrom leak-proof tunnel that is burrowed deep in the protein and connects the CODH and ACS active sites. We demonstrated that a spectroscopically well-studied intermediate (called the "NiFeC species") is a catalytically competent intermediate in the synthesis of acetyl-CoA. This intermediate contains the substrate, CO, bound end-on to one of the metals at the ACS active site. Whether this is an intermediate or an interesting artifact (or perhaps inhibitory state) has been hotly debated among several groups in this field. We
showed that the rates of formation and decay are consistent with its intermediacy and showed that this intermediate fits securely in a kinetic model of the overall reaction. We demonstrated that the ubiquitous coenzyme, Coenzyme A, profoundly influences the rate of electron transfer in the enzyme pyruvate ferredoxin oxidoreductase (PFOR). One of the electron transfer steps occurs 1 million-fold faster in the presence than in the absence of CoA. Nearly all of this rate acceleration derives from the sulfur group of CoA, which makes up only 4% of the total mass of this large cofactor. Our results implicate that a highly reducing radical is formed that contains thiamine pyrophosphate, CoA, and the hydroxyethyl group of pyruvate. We postulated that CoA forms part of a "wire" over which electrons can rapidly transfer from a radical intermediate to an iron-sulfur cluster. We cloned and sequenced PFOR. METHANOGENESIS There has been a long-standing puzzle about how the key enzyme in this
pathway is activated. It was known that the strong reductant Ti(III) citrate can activate the enzyme, but where the electrons go has been a mystery. It was assumed that they went to the nickel, which is at the core of the coenzyme F430 macrocyclic structure. However, collaborative studies between Hoffman and myself have shown over the past few years that the nickel ion stays in the same Ni(I) redox state in the "ready" and "active" state. In a collaborative study with Maroney and Bocian, we showed that the macrocycle itself undergoes reduction by two electrons. DEHALOGENATION OF PCBs & RELATED CHLORINATED AROMATICS We characterized a vitamin B12 and iron-sulfur containing dehalogenase and showed for the first time that it will use a hydroxy-PCB as a substrate. This has been published. We also have begun to unravel the regulation of the PCB utilization pathway. We have characterized the major regulatory protein in this pathway, called cprK.
Impacts
The CODH/ACS crystal structure was covered by perspectives in Science and Chemical and Engineering News and several press releases. This was the first time three transition metals had been found in a protein and, amazingly, these metals are a 6-metal "supercluster". The trapped acetyl-Cu intermediate visualized at 2.2 angstroms resolution validates the proposal of a "bio-organometallic" reaction sequence. The structural information on 140 angstrom tunnel buried in the protein results help explain how bacteria deal with an energy-rich biochemical intermediate that is a toxic gas and how they protect their host against the toxic effects. Demonstration that the carbonylated intermediate is indeed a catalytically important species resolves a hotly debated mechanistic question and makes determination of which metal in this supercluster binds CO all the more important. The studies of electron transfer in PFOR uncovered a new role for Coenzyme A in biochemistry. The nickel
coenzyme F430 had been known to be the most reduced tetrapyrrole in nature. We found that even further reduction is required to activate the cofactor bound to the enzyme methyl-Coenzyme M reductase. PCBs are extremely toxic environmental pollutants. Characterizing how microbes respond to the presence of the chlorinated aromatic is important in understanding this process.
Publications
- Seravalli, J., Kumar, M., and *Ragsdale, S.W. (2002) Rapid Kinetic Studies of Acetyl-CoA Synthesis: Evidence Supporting the Catalytic Intermediacy of a Paramagnetic NiFeC Species in the Autotrophic Wood-Ljungdahl Pathway. Biochemistry 41: 1807-1819.
- Boll, M., Fuchs, G., Meier, C., Trautwein, A., Kasmi, A.E., Ragsdale, S.W., Buchanan, G., and *Lowe, D.J. (2001) Redox centers of 4-hydroxybenzoyl-CoA reductase, a member of the xanthine oxidase family of molybdenum containing enzymes. Journal of Biological Chemistry 276: 47853-62.
- Seravalli, J., Brown, K.L., and *Ragsdale, S.W. (2001) Acetyl-Coenzyme A Synthesis From Unnatural Methylated Corrinoids: Requirement for "Base-Off" Coordination at Cobalt, Journal of the American Chemical Society 123: 1786-1787.
- Murakami, E., Deppenmeier, U., and *Ragsdale, S.W. (2001) Characterization of the Intramolecular Electron Transfer Pathway from 2-Hydroxyphenazine to the Heterodisulfide Reductase from Methanosarcina thermophila. Journal of Biological Chemistry 276: 2432-2439.
- Horng, Y.-C., Becker, D.F., and *Ragsdale, S.W. (2001) Requirement of Coenzyme B for Cleavage of the C-S bond of methyl-SCoM. Biochemistry 40:12875-12885.
- Seravalli, J., and *Ragsdale, S.W. (2000) Channeling of Carbon Monoxide During Anaerobic Carbon Dioxide Fixation Biochemistry 39: 1274-1277.
- Telser, J., Horng, Y.-C., Becker, D., Hoffman, B., and *Ragsdale, S.W. (2000) On the assignment of nickel oxidation states of the Ox1 and Ox2 Forms of Methyl-Coenzyme M Reductase. Journal of the American Chemical Society 122: 182-183.
- Murakami, E., and *Ragsdale, S.W. (2000) Evidence for Intersubunit Communication During Acetyl-CoA Cleavage by the Multienzyme CO Dehydrogenase/Acetyl-CoA Synthase Complex from Methanosarcina thermophila: Evidence that the Beta Subunit Catalyzes C-C and C-S Bond Cleavage. Journal of Biological Chemistry 275: 4699-4707.
- Doukov, T., *Ragsdale, S.W., and Stezowski, J. (2000) Crystal structure of a methyltetrahydrofolate and corrinoid dependent methyltransferase, Structure with Folding and Design, 8: 817-830.
- Ralston, C.Y., Wang, H., Ragsdale, S.W., Dumar, M., Spangler, N.J., Ludden, P.W., Gu, W., Jones, R.M., Patil, D.S., and *Cramer, S.P. (2000) Characterization of heterogeneous nickel sites in CO dehydrogenases from Clostridium thermoaceticum and Rhodospirillum rubrum by nickel L-edge X-ray spectroscopy. Journal of the American Chemical Society 122: 10553-10560.
- Doukov, T. I., Iverson, T., Seravalli, J., Ragsdale, S. W., and *Drennan. C. L. (2002) An Unique Ni-Fe-Cu Center in the Crystal Structure of Bifunctional Carbon Monoxide Dehydrogenase/Acetyl-CoA Synthase. Science 298: 567-572.
- Tang, Q., Carrington, P. E., Horng, Y.-C., Maroney, M. J., *Ragsdale, S. W., and *Bocian. D. F. (2002) X-Ray Absorption and Resonance Raman Studies of Methyl-Coenzyme M Reductase Indicating That Ligand Exchange and Macrocycle Reduction Accompany Reductive Activation. Journal of the American Chemical Society 124: 13242-13256.
- Furdui, C., and *Ragsdale, S.W. (2002) The Roles of Coenzyme A in the Pyruvate:Ferredoxin Oxidoreductase Reaction Mechanism: Rate Enhancement of Electron Transfer from a Radical Intermediate to an Iron-Sulfur Cluster, Biochemistry, 41: 9921-9937.
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Progress 10/01/00 to 09/30/01
Outputs
Metabolism of Carbon Monoxide and Other Xenobiotics We performed rapid kinetic studies to test whether or not of a previously detected paramagnetic species is an intermediate in the autotrophic Wood-Ljungdahl Pathway. There has been active debate about whether or not this "Paramagnetic NiFeC Species" that is derived from carbon monoxide is an intermediate or not. We have conclusively demonstrates that it is an intermediate. We also described the first example of a purified enzyme that can remove the halogen group from a PCB derivative (the hydroxy-PCB). Methane formation There has been a lot of controversy about the oxidation state of Nickel in the key enzyme in methanogenesis. We have used a number of experimental approaches to demonstrates that it is Ni(I). We also demonstrated that the formation of methane involves an unusual reaction in which the two cofactors, methyl-CoM and Coenzyme B form a linkage, which activates the methyl group, leading to its cleavage and
to methane formation. We also elucidated the electron transfer pathway within one of the key proteins in methanogenesis, called heterodisufide reductase. Enzyme Structure and Function We demonstrated the mechanism of a key methyl transfer reaction from cobalt to nickel in the enzyme acetyl-CoA synthase and explained why the corrinoid protein that is the methyl donor is in an unusual 5-coordinate state. We also characterized the properties of an enzyme that can remove the methyl group from phenyl methyl ethers, which are lignin metabolites and also herbicides like dicamba.
Impacts
Demonstration that the "Paramagnetic NiFeC Species" is an intermediate will have a major impact on the bioinorganic chemistry and mechanistic enzymology community. The description of the metabolism of hydroxy-PCBs by a pure enzyme is important because it could spur development of a biological remediation process involving enzymes. Elucidating the oxidation state of Nickel in the key enzyme in methanogenesis impacts the bioinorganic and mechanistic enzymology community. There has been a lot of controversy about this issue and I think our series of four papers on this topic settle this. There has been active discussion about the importance of coordination chemistry on the mechanism of methyl transfer. This work ties the inorganic model chemistry and the biochemistry together. The impact of the enzymatic removal of the methyl group from phenyl methyl ethers is in the better understanding of how to metabolize lignin and herbicides like dicamba.
Publications
- Naidu, D., and Ragsdale, S.W. (2001) Characterization of a three-component vanillate O-demethylase from Moorella thermoacetica, J Bacteriol. 183, 3276-81.
- Ragsdale, S.W. (2001) One-carbon chemistry: CO2, CO, CH4, formate: 1. Reductive chemistry, p. in press. In J. S. Valentine, I. Bertini, and H. Gray (ed.), Biological Inorganic Chemistry: Structure and Reactivity. University Science Books.
- Seravalli, J., Brown, K.L., and Ragsdale, S.W. (2001) Acetyl-Coenzyme A Synthesis From Unnatural Methylated Corrinoids: Requirement for "Base-Off" Coordination at Cobalt, J Am Chem Soc. 123, 1786-1787.
- Telser, J., Davydov, R., Horng, Y.C., Ragsdale, S.W., and Hoffman, B.M. (2001) Cryoreduction of methyl-coenzyme M reductase: EPR characterization of forms, MCR(ox1) and MCR(red1), J Am Chem Soc. 123, 5853-60.
- Boll, M., Fuchs, G., Meier, C., Trautwein, A., Kasmi, A.E., Ragsdale, S.W., Buchanan, G., and Lowe, D.J. (2001) Redox centers of 4-hydroxybenzoyl-CoA reductase, a member of the xanthine oxidase family of molybdenum containing enzymes, J Biol Chem., in press.
- Horng, Y.-C., Becker, D.F., and Ragsdale, S.W. (2001) Mechanistic Studies of Methane Biogenesis by Methyl-Coenzyme M Reductase: Evidence that Coenzyme B Participates in Cleaving the C-S Bond of Methyl-Coenzyme M, Biochemistry. 40, 12875-85.
- Krasotkina, J., Walters, T., Maruya , K.A., and Ragsdale, S.W. (2001) Characterization of the B12- and Iron-Sulfur Containing Reductive Dehalogenase from Desulfitobacterium chlororespirans, Journal of Biological Chemistry. 276, 40991-7.
- Murakami, E., Deppenmeier, U., and Ragsdale, S.W. (2001) Characterization of the Intramolecular Electron Transfer Pathway from 2-Hydroxyphenazine to the Heterodisulfide Reductase from Methanosarcina thermophila, Journal of Biological Chemistry. 276, 2432-2439.
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Progress 10/01/99 to 09/30/00
Outputs
There are three subprojects covered under this project. In the project dealing with how bacteria make acetic acid, we determined the crystal structure of a key enzyme in the Wood-Ljungdahl pathway of autotrophic CO2 fixation - the methyltransferase. This is a new member of the TIM barrel structural family. The work represents the first structure of a pterin-dependent methyltransferase. We also determined that the role of pyruvate ferredoxin oxidoreductase is not only to link glycolysis to the Wood-Ljungdahl pathway, but also to drive the reverse reaction - the synthesis of pyruvate from acetyl-CoA and CO2. Thus it is a player in cell carbon synthesis from CO2. In studies of the central enzyme of this pathway, we found that CO is produced from CO2 at the active site of the CO dehydrogenase subunit and then is "channeled" to the active site of the acetyl-CoA synthase subunit. This channel sequesters the CO from the solvent, which enhances the efficiency of the enzyme,
retaining this high energy compound, and protects the host organism from the highly toxic effects of this gas. In the project dealing with how bacteria make methane, we determined that the central enzyme in the conversion of acetate to methane requires an association between the two integral subunits - CO dehydrogenase and acetyl-CoA synthase. Our results indicate that this association allows control of electron and carbon flow between the two subunits. In studies of the final step of methane formation, which is catalyzed by methyl-Coenzyme M reductase, we found that one form of the enzyme that had been called "the oxidized enzyme" actually has its Nickel active site in a reduced Ni(I) state. This finding significantly alters our view of the catalytic mechanism of this enzyme. In a third project, dealing with how bacteria can degrade environmentally hazardous chlorinated aromatics, we have isolated the enzyme responsible for catalyzing the dehalogenation reaction and studied its
properties.
Impacts
Nature cycles tremendous amounts of carbon through the anaerobic pathways of acetic acid and methane formation. CO2 fixation associated with these processes dwarfs the chemical industries production of CO2 or the suggested schemes for burying or sequestering CO2. The acetic acid that is produced is an important biochemical feedstock and is an important competitor for the formation of methane, which is a greenhouse gas. Our results provide new insight into how these processes occur. Our studies are uncovering possible ways to control the natural flux between methane and acetic acid production. Control of these processes might offer a way to control greenhouse gas emissions. The understanding of how bacterial enzymes remove the chloride group might help us design ways to detoxify PCBs and other environmentally hazardous halogenated aromatics.
Publications
- Furdui, C., and S.W. Ragsdale. 2000. The role of pyruvate: ferredoxin oxidoreductase in pyruvate synthesis during autotrophic growth by the Wood-Ljungdahl pathway. J Biol Chem 275:28494-28499.
- Doukov, T., J. Seravalli, J. Stezowski, and S.W. Ragsdale. 2000. Crystal structure of a methyltetrahydrofolate and corrinoid dependent methyltransferase. Structure 8:817-830.
- Murakami, E., and S.W. Ragsdale. 2000. Evidence for Intersubunit Communication During Acetyl-CoA Cleavage by the Multienzyme CO Dehydrogenase/Acetyl-CoA Synthase Complex from Methanosarcina thermophila: Evidence that the Beta Subunit Catalyzes C-C and C-S Bond Cleavage. Journal of Biological Chemistry 275:4699-4707.
- Ragsdale, S.W. 2000. Anaerobic one-carbon catalysis, In I. T. Horvath, E. Iglesia, M. T. Klein, J. A. Lercher, A. J. Russell, and E. I. Stiefel (ed.), Encyclopedia of catalysis. John Wiley and Sons, Inc., New York
- Ragsdale, S.W. 2000. Nickel Containing CO Dehydrogenases and Hydrogenases. In N. Scrutton (ed.), Enzyme-catalyzed electron-radical transfer, vol. 36. Plenum Press, New York
- Seravalli, J., and S.W. Ragsdale. 2000. Channeling of Carbon Monoxide during Anaerobic Carbon Dioxide Fixation. Biochemistry 39:1274-1277.
- Telser, J., Y.-C. Horng, D. Becker, B. Hoffman, and S.W. Ragsdale. 2000. On the assignment of nickel oxidation states of the Ox1 and Ox2 Forms of Methyl-Coenzyme M Reductase. Journal of the American Chemical Society 122:182-183.
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Progress 10/01/98 to 09/30/99
Outputs
Some of the major progress has been in our studies of anaerobic CO2 fixation by acetic acid producing microbes. We discovered that nitrogen oxides regulate the expression of genes encoding the key enzymes in this pathway. The NO's repress these genes while CO2 derepresses. We also characterized a radical intermediate in the mechanism of the enzyme that oxidizes pyruvate, pyruvate:ferredoxin oxidoreductase. A major focus was on characterizing how methyl groups are transferred in the CO2 fixation pathway. The microbes use vitamin B12, which undergoes methylation at cobalt and then subsequent demethylation. This reaction involves a nucleophilic attack by a metal center acting as a nucleophile (Co(I)) on an electrophile (the N-5 methyl group of CH3-H4folate). We have been focusing on how the nucleophile is generated and how the electrophile is activated. One of the unsolved questions is how the methyl group of CH3-H4folate, which is quite stable in solution, is activated
in this class of enzymes. We found that the heteroatom (nitrogen 5 of the pterin ring) adjacent to the methyl group undergoes protonation. This makes the methyl group more electrophilic and activates it toward nucleophilic attack by cobalt. Another question is how the nucleophile, Co(I) of the B12-containing methyl acceptor protein, is activated and maintained in the active state. We found that the iron-sulfur cluster, which is a component of the other subunit of the protein, is required for activation of cobalt. Electrons are transferred to cobalt through this cluster.
Impacts
Besides being harmful to humans, nitrogen oxides decrease the activity of anaerobic microbes in the soil, in rice paddies, and in the rumen. We found at least one mechanism is by repressing gene expression. Methyl group transfers are important in many biochemical reactions. We have shown that proton and electron transfer reactions play key roles in controlling these methyl transfer reactions.
Publications
- Arendsen, S., Soliman, M., and Ragsdale, S.W. 1999. Nitrate-Dependent Regulation Of Acetate Biosynthesis And Nitrate Respiration by Clostridium thermoaceticum. J. Bacteriol. 181: 1489-1495.
- Bouchev, V.F., Furdui, C.M., Menon, S., Muthukumaran, R.B., Ragsdale, S.W., and McCracken, J. 1999. ENDOR studies of pyruvate: ferredoxin oxidoreductase reaction intermediates. J. Am. Chem. Soc. 121: 3724-3729.
- Seravalli, J., Zhao, S.Y., and Ragsdale, S.W. 1999. Mechanism of Transfer of the Methyl Group from (6S)-Methyltetrahydrofolate to the Corrinoid/Iron-Sulfur Protein Catalyzed by the Methyltransferase from Clostridium thermoaceticum: A Key Step in the Wood-Ljungdahl Pathway of Acetyl-CoA Synthesis. Biochemistry: 38, 5728-5735.
- Seravalli, J., Shoemaker, R.K., Sudbeck, M.J., and Ragsdale, S.W. 1999. Binding of (6R,S)-Methyltetrahydrofolate to Methyltransferase from Clostridium thermoaceticum: Role of Protonation of Methyltetrahydrofolate in the Mechanism of Methyl Transfer. Biochemistry: 38, 5736-5745.
- Menon, S., and Ragsdale, S.W. 1999. The role of an iron-sulfur cluster in an enzymatic methylation reaction: methylation of CO dehydrogenase/acetyl-CoA synthase by the methylated corrinoid iron-sulfur protein. J. Biol. Chem: 274: 11513-8.
- Fonticilla-Camps, J.-C., and Ragsdale, S.W. 1999. Nickel-iron-sulfur active sites: hydrogenase and CO dehydrogenase, in press. In R. Cammack and A. G. Sykes (ed.), Advances in Inorganic Chemistry. Academic Press, Inc., San Diego.
- Ragsdale, S.W. 1999. The Acetogenic Corrinoid Proteins, p. in press. In R. Banerjee (ed.), Vitamin B12, vol. 1. John Wiley and Sons, New York.
- Ragsdale, S.W. 1999. Biocatalytic One Carbon Conversion. Invited article for Encyclopedia of Catalysis, John Wiley and Sons, Inc, New York, Edited by Horvath, I.T, in press.
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