Cyclopropane ring fission

Rat liver microsomes act on 1,1-dichloro-cis -diphenylcyclopropane to form several products such as 2-chloro-3-oxo-1,3-diphenyl-1-propene. This involves an unusual type of ring fission which is considered to form 2,3-dichloro-1,3-diphenyl-1-propene as the initial product F573 . Methylococcus capsulatus soluble methane monooxygenase (E.C. 1.14.13.25) converts cyclopropylbenzene into benzyl alcohol. 3-Phenylprop-2-en-1-ol is also formed, and this may be an intermediate F278 . 1.6 Reactions...

Hydroxyquinol reductase

Reduction at the same catalytic locus to form 2-amino-5-oxocyclohex-1-enecarboxyl CoA K215 . Desulphovibrio inopinatus enzyme forms, probably, 1,2,4-trihydroxycyclohexa-1,3-diene from hydroxyquinol K483 . trihydroxy-1-tetralone) and 1,3,8-trihydroxynaphthalene to vermelone K703 . Magnaporthe grisea enzyme (vermelone formation) requires NADPH as co-substrate, and is inhibited by tricyclazole. It is an essential step in the formation of a melanin that is required for the initiation of blast...

PHydroxybenzoate 1hydroxylase

Second substrate is 2,3-dihydroxybenzoate H438 . Klebsiella pneumoniae enzyme requires NAD(P)H the activity is rapidly destroyed at 45 G199 . It is also found in Bacillus and Bacterium A489, B161 . (4-hydroxybenzoate 3-monooxygenase, E.C. 1.14.13.2 and 1.14.13.33) -Hydroxybenzoate + O2 0 protocatechuate Corynebacterium cyclohexanicum enzyme is a monomer, molecular weight 47 000, and contains FAD. It requires Mg2+ and NADH or NADPH, and is specific for p -hydroxybenzoate D554 . Moraxella enzyme...

Phenylacetate 4hydroxylase

Diethyldithiocarbamate and a,a-dipyridyl are inhibitors A203 . This activity has been demonstrated in bacteria B950 , Aspergillus niger A3787 , A. fumigatus C484 , Brevibacterium linens D623 and Trichosporon cutaneum E332 . Phenylacetate 0 -hydroxyphenylacetate This activity has been demonstrated in bacteria B950 , Brevibacterium linens D623 , Trichosporon cutaneum E332 and Aspergillus niger A329 . Mandelate 4-monooxygenase (E.C. 1.14.16.6) Pseudomonas convexa enzyme, molecular weight 91 000...

Oxidations and reductions of substituent side chains and nonaromatic ring systems without altering chain length

3.1 Hydroxylation of the carbon side-chain Dopamine-P-hydroxylase (dopamine-b-monooxygenase DBH E.C. 1.14.17.1) Ar.CH2.CH2 NH2 + ascorbate + O20 Ar.CHOH.CH2NH2 + dehydroascorbate Substrates for this enzyme are phenethylamines, including tyramine and dopamine. The physiologically important substrate dopamine yields the neurotransmitter noradrenaline. Human serum enzyme requires ascorbate and is stimulated by fumarate, N-ethylmaleimide and by low concentrations of copper. Two isozymes are found,...

Dihydrochelirubine 12monooxygenase

Thalictrum bulgaricum enzyme, optimum pH 8.5, is a microsomal P450, specific for position 12. It requires oxygen and NAD(P)H K776 . Rat liver mitochondrial enzyme, which requires NADPH, has a molecular weight of 52 000 F686 . Methylococcus capsulatus methane monooxygenase (E.C. 1.14.13.25) hydroxylates benzene and halobenzenes by a NIH shift mechanism (products not stated) F278 . Many other studies have also detected this reaction. Penicillium patulum enzyme acts on m-cresol to form...

Trihydroxytoluene oxygenase

This reaction has also been observed in Pseudomonas A2697 , Sporotrichum B124 , Trichosporon B368, D232 , Arthrobacter H270 , Aspergillus H236 , Bradyrhizobium J484 and Streptomyces H347 . Burkholderia enzyme is apparently a dimmer the molecular weight was found to be 67 000 or 78 000 by different methods. It contains two Fe mol and is stimulated by Fe2+ and ascorbate. The product is 2,4-dihydroxy-5-methyl-cis, cis -muconic semialdehyde. Other catechols are also substrates J903 ....

Tryptophan 5hydroxylase

Mechanistic studies using beef liver enzyme and substrate specifically labelled with deuterium in the methylene group indicate that side-chain migration occurs with retention of configuration at the methylene group B904 . Studies using an enzyme with unspecified origin, but presumably mammalian, have shown that the phenolic hydroxyl group is not exchanged during the reaction. This indicates that, although still possible, an intermediate with a peroxide 1,4-bridge is most unlikely A844 ....

Pvp

* with whole microorganisms A3974 . * with whole microorganisms A3974 . 2.2.1. Tyrosinase and unspecified types. Apple enzyme is composed of isozymes, molecular weights 46000, 120000, 460 000 and 800000. They are considered to be polymers of a common monomer A1133 . Amasya apple enzyme contains three isozymes, with optima at pH 6.6 9.0, dependent on the substrate substrates are catechol, 4-methylcatechol, pyrogallol and l-dopa H567 . Four Arachis peroxidase isozymes, which additionally exhibit...

Hydroxy2naphthoate 12dioxygenase

1-Hydroxy-2-naphthoate 1,2-dioxygenase Nocardioides enzyme, monomeric molecular weight 45 000 and native molecular weight 270 000, contains one mol Fe2 + mol, which is essential for activity. The product is 4-(o -carboxyphenyl)-2-oxobutyrate J598 . Coccus enzyme requires oxygen and is activated by Fe2+ E730 . Rat liver converts thyroxine into diiodotyrosine the reaction requires oxygen C809 . It is also catalyzed by human thyroid peroxidase D553 . Pseudomonas cruciviae degrades diphenyl ether...

Rcho 0 Rcooh

Pig brain contains an enzyme that oxidizes the physiologically important aldehydes 5-hydro-xyindole-3-acetaldehyde, 4-hydroxy-3-methoxy-and 3,4-dihydroxyphenylacetaldehydes, d-3,4-dihydroxyphenylglycollaldehyde as well as d- and l -p -hydroxyphenylglycollaldehyde A1287 . Rat liver enzyme is found in mitochondria (three isozymes, pI 5.4, 5.6 and 6.9) and cytosol (five isozymes, pI 5.8, 6.05, 6.15, 6.6 and 7.4). All of them oxidize p -nitrobenzaldehyde and 3,4-dihydroxyphenylacetaldehyde B659 ....

Catechol 23dioxygenase

A. calcoaceticus enzyme, molecular weight 81 000-85 000 (using different measuring techniques), is composed of two monomers and contains two mol Fe mol. Additional substrates (poor) are 3- and 4-methylcatechol and 3-iso-propylcatechol, but a number of other catechols are not substrates. It has a broad optimum at pH 7-9, which coincides with its stability range. Its amino acid composition has been determined methionine is the amino terminal residue A2640 . Rhizobium leguminosarum enzyme is a...

Phenol 2monooxygenase

Oestrone is a substrate in rat and hamster A2408, C896, G625 . A human enzyme hydroxylates 17p-oestradiol at the 7a-position A2465 . The same reaction is observed in rat A1487, A2192 . Oestrone is a substrate in rat and hamster A2408, C896, G625 . A human enzyme hydroxylates 17b-oestradiol at the 7b-position A2465 . This activity is found in Neurospora, with 17b-oestradiol as substrate A944 . Rat liver micromes hydroxylate 17b-oestradiol and oestriol at the 14a-position H342 . A...

MHydroxybenzyl alcohol 6hydroxylase

M -Hydroxybenzyl alcohol 6-hydroxylase Penicilliun patulum microsomal enzyme, optimum pH 7.5, requires NADPH in the formation of gentisyl alcohol. It is suggested that the enzyme is m -cresol 2-hydroxylase A2314 . 2, 3-dihydroxybenzoate (pyrocatechuate) Rat liver enzyme is considered to act via a free radical that non-specifically causes hydroxylation of salicylate rather than by the action of a hydroxylase J754 . Rat liver enzyme is considered to act via a free radical that non-specifically...

LDopachrome tautomerase

D-dopachrome into 5,6-dihydroxyindole. The enzyme source is not clear from Chemical Abstracts it is claimed to be a rat enzyme, but it may be the same as that described in another publication, found in human lymphocytes. The latter is a macrophage migration inhibition factor in addition to its tautomerase activity J475, J514 . L-Dopachrome tautomerase (E C. 5.3.3.12) Mouse melanoma enzyme forms 5,6-dihydroxyindole-2-carboxylate as the initial product. The apoenzyme is activated by Zn2 + , but...

Anthranilate 5hydroxylase

Purified enzyme also catalyzes the formation of pyrocatechuate, which suggests that it also shows anthranilate 2,3-hydroxylase (deaminating) activity (E.C. 1.14.13.35) it is claimed that both activities reside on the same molecule. Cu2+ and p -chloromercuribenzoate are inhibitory D231 . This reaction is also observed in rat liver and brain A3653, F676 . This reaction is observed in rat liver A3653, D296 . Indole 4-hydroxylase is found in pumpkin A3530 . A similar reaction occurs...

Oxidations and reductions involving the aromatic nucleus and nonorganic substituents

2.1 Hydroxylation of the aromatic nucleus 2.1.1 Hydroxylations associated with physiologically important amino acids and hormones Phenylalanine hydroxylase (phenylalanine 4-monooxygenase E.C. 1.14.16.1) This vertebrate enzyme degrades dietary phenylalanine in excess of requirements for protein and hormone formation. In a group of closely associated inherited diseases in man (e.g. phenylketonuria, hyperphenylalaninaemia) that result in moderate to severe mental retardation, this enzyme is either...

Formation and degradation of sidechains

Human bone marrow supplemented with S-adenosylmethionine converts benzene into toluene, which in turn yields o -, m - and p -xylenes F853 . This may account for the apparent hydroxymethylation of benzene (Sloane, N.H., Biochim. Biophys. Acta (1965), 107, 599 Sloane, N.H., Heinemann, M., Biochim. Biophys. Acta (1970), 201, 384). Rat is able to incorporate a methyl group at positions 7 and 12 of benzanthracene and possibly its metabolites. Incorporation was not observed with a range of...

Benzophenone synthase

Absent, there must be a suspicion that the preparations were all contaminated with this enzyme. Benzophenone synthase (E.C. 2.3.1.151) Centaurium erythraea enzyme, optimum pH 7.5, acts on m -hydroxybenzoyl CoA and malonyl CoA to form 2,3',4,6-tetrahydroxybenzophenone J35 . Aspergillus parasiticus converts hexanoate or pentanoate into norsolorinate, a polyphenolic anthraquinone, which is a postulated precursor of aflatoxin Bi. With pentanoate, an additional reaction product with a 5-oxopentane...

Rcocooh 0 Rcho

The reaction has been found in Bragyrhizobium elkanii J189 , E. coli H348 and Azospirillum lipoferum F49 . Enterobacter cloacae enzyme has been reviewed K792 . Indole-3-pyruvate ferredoxin oxidoreductase Pyrococcus furiosus enzyme is a tetramer composed of two pairs of subunits, molecular weights 23 000 and 66 000, optimum pH 8.5-10.5, with one thiamine, a cluster of 4 4Fe-4S 2 + '1 + and one 3Fe-4S 0,1+ units, and a requirement for CoA. The products from indole-3-pyruvate, phenylpyruvate and p...

RCH30 rch2oh

Rat liver enzyme oxidizes 7-methyl- and 7,12-dimethylbenzanthracene, incorporating oxygen from molecular oxygen, but not from water A339 . A Pseudomonas putida enzyme, which acts on 4-hydroxy-3-methylbenzoate is a 2-protein system, molecular weight 115 000, that appears to be composed of a flavin-containing hydroxylase and an electron-transfer system that uses NADH. It is claimed to be an unusual type of mixed-function oxidase F223 . The electron transfer system appears to be a flavocytochrome...

Rchohcooh 0 Rcocooh

Rhodotorula graminis l-( )-mandelate dehydrogenase is a tetramer, monomeric molecular weight 59 100, that contains one mol each of haem and FMN per subunit. The optimum pH is 7.9, and pI 4.4. It acts on mandelate and a series of nuclear-substituted analogues H90 and is stereospecific G904 . Both d- and l-dehydrogenases are inducible. l-Dehydrogenase, optimum pH 7.0, requires dichlorophenolindophenol as reductant, and may be membrane-bound activity is enhanced by phenazine methosulphate....

Tyramine 3hydroxylase

Ascorbate activates, and diethyldithiocarbamate is inhibitory A541 . Berberis stolonifera phenoloxidase, molecular weight 60 000 and optimum pH 6.0, oxidizes both l-tyrosine and tyramine, as well as some phenolic tetrahydroisoquinoline natural products. Both ascorbate and oxygen are required for activity F855 . Horseradish peroxidase and peroxide act on mixtures of dopa and phenols the phenols accelerate the oxidation of dopa, although when the phenol used is...

Peptide tryptophan 23dioxygenase

Wheat germ optimum pH about 8 and rat liver enzymes act on tryptophan residues in polypeptides such as pepsin and trypsin, converting them into kynurenine residues K823 . Indole 2,3-dioxygenase E.C. 1.13.11.17 In rat, indole is converted into N-formylanthranilate, which is the expected initial product of indole ring fission, as well as anthranilate D158 . Jasminum grandiflorum leaf enzyme, optimum pH 4.8, forms anthranilate from the substrate. Other substrates are 5-hydroxy- and 5-bromoindole....

Hydroxylation by monophenol monooxygenase

A manner similar to beef brain enzyme see below A3017 . Beef corpus striatum enzyme molecular weight about 60 000 is activated by incubation with ATP and cyclic AMP-dependent protein kinase, which yields a phosphorylated hydroxylase containing one mol of phosphate B413 . Caudate nucleus enzyme is activated by phosphatidylserine and other polyanions, which reduce Km for the pterin cofactor. Phosphatidylserine raises the optimum pH from about 6 by 1 unit, whereas the effect of heparin is...

RNO20 rnh2

This reaction often, if not always, involves the formation of intermediate nitroxides and hydroxylamines, although in many studies these intermediates were not detectable. Human placenta reduces p -nitrobenzoate to p-aminobenzoate. Fractionation indicates that Reduction of nitro compounds to anilines the active enzymes are haemoglobin or methae-moglobin. Studies with pure proteins found that the reaction can be catalyzed by haem-containing proteins such as methaemoglobin, metmyoglobin and cytochrome c, with NADPH as reducing agent. Placental reduction and the haem-model system haematin, NADPH, FMN and p -nitrobenzoate are inhibited by carbon monoxide A621 . Formation of p -aminobenzoate from p -nitrobenzoate is observed in conventional rats, but is, relatively, very low in germ-free animals. Studies with microorganisms have found reduction by the gut flora Lactobacillus plantarum, Bacteroides fragilis, Peptostreptococcus productus, Clostridium, Proteus mirabilis, S. faecalis and E....