Monooxygenase, catalysis

Klinman, J.P., Krueger, M., Brenner, M. and Edmondson, D.E. (1984) Evidence for two copper atoms/subunit in dopamine beta-monooxygenase catalysis. The Journal of Biological Chemistry, 259, 3399-402. 

A. G. Katopodis, K. Wimalasena, J. Lee, and S. W. May, Mechanistic studies on non-heme monooxygenase catalysis Epoxidation, aldehyde formation, and demethylation by the omega-hydroxylation system of Pseudomonas oleo-vorans, J. Am. Chem. Soc., 206 7928 (1984). 

P450 monooxygenase catalysis that was available at the time of the previous edition of this volume. 

Brazeau BJ, Lipscomh JD. 2003. Key amino acid residues in the regulation of soluble methane monooxygenase catalysis hy component B. Biochemistry 42 5618-5631. 

All characterized BVMOs contain a flavin cofactor that is crucial for catalysis while NADH or NADPH is needed as electron donor. An interesting observation is the fact that most reported BVMOs are soluble proteins. This is in contrast to many other monooxygenase systems that often are found to be membrane-bound or membrane-associated. In 1997, Willetts concluded from careful inspection of... 

Schmid, A., Hofstetter, K., Feiten, H.J., Holhnann, R, Witholt, B. (2001) Integrated Biocatalytic Synthesis on Gram Scale The Highly Enantio Selective Preparation of Chiral Oxiranes with Styrene Monooxygenase. Advanced Synthesis Catalysis, 343(6-7), I il-l il. 

Other non-heme enzymes that use dioxygen are 4-methoxy-benzoate O-demethylase, extradiol catechol dioxygenases, the oxidoreductase isopenicillin N synthase, and a-keto acid-dependent enzymes (28). Moreover, the BH4-dependent glyceryl-ether monooxygenase (GEM) also appears to be dependent on nonheme iron for catalysis (see also Section I.E). 

Although flavoprotein monooxygenases form a separate class, formally they can be considered to react according to Equation (4) as far as the redox states involved in catalysis are concerned. 

Pyridine nucleotide-dependent flavoenzyme catalyzed reactions are known for the external monooxygenase and the disulfide oxidoreductases However, no evidence for the direct participation of the flavin semiquinone as an intermediate in catalysis has been found in these systems. In contrast, flavin semiquinones are necessary intermediates in those pyridine nucleotide-dependent enzymes in which electron transfer from the flavin involves an obligate 1-electron acceptor such as a heme or an iron-sulfur center. Examples of such enzymes include NADPH-cytochrome P4S0 reductase, NADH-cytochrome bs reductase, ferredoxin — NADP reductase, adrenodoxin reductase as well as more complex enzymes such as the mitochondrial NADH dehydrogenase and xanthine dehydrogenase. 

The most widespread efforts made towards the achievement of selective oxidation of alkanes are targeted on methane, a principal constituent of natural gas f 6-8]. Activation of the very stable C-H bond of methane is a particularly demanding problem. One example in which this has been achieved on industrial scales is the Degussa process [9], Methane is coupled to ammonia by heterogeneous catalysis in order to produce HCN, an important fundamental material for industrial chemistry. An unsolved problem is the selective oxidation of methane to methanol a reaction that would convert the methane gas into a transportable liquid. In nature, monooxygenases have evolved. These are able to activate molecular oxygen and to... 

How can a simple cofactor, such as heme, give rise to a wide spectrum of protein functionalities While the Fe(III)/Fe(II) couple has a standard redox potential of 0.77 V, when complexed with a protoporphyrin to form free heme, it may decrease to —0.115 V [3-5]. When heme is introduced into a protein matrix, redox potential shows an impressive variation of around 1 V. The electrochemical data for structurally characterized heme proteins involved in electron transfer and redox catalysis has been compiled at the Heme Protein Database (HPD, http //heme.chem. columbia.edu/heme) [6]. The database comprises not only peroxidases but also catalases, oxidases, monooxygenases, and cytochromes. From b-type heme with histidine-tyrosine ligation (E° = 0.55 V) to c-type heme with histidine-methionine... 

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