Monophenols

Monophenols 2,6-di- / l -butylphenol [128-39-2] C14H22O F, GAS, PO Ethyl Corp. Schnectady Chemicals, Inc. 

Oxidation of monophenols to polyphenols or oxidation of aromatic methyl groups by persulfates (Caro s acxJ)... 

Various phenolic acids have been reported to inhibit IAA oxidase (9, 52,120), and other phenols may act as cofactors of IAA oxidase (144). In general, the cofactors of IAA oxidase are monophenols, whereas the inhibitors of the system are polyphenols, with o-dihy-droxyphenols being the most inhibitory (52, 65). Unsaturated lactones have also been reported to inhibit IAA oxidase (2, 52). 

Polyphenoloxidase (PPO, EC 1.14.18.1) is one of the most studied oxidative enzymes because it is involved in the biosynthesis of melanins in animals and in the browning of plants. The enzyme seems to be almost universally distributed in animals, plants, fungi, and bacteria (Sanchez-Ferrer and others 1995) and catalyzes two different reactions in which molecular oxygen is involved the o-hydroxylation of monophenols to o-diphenols (monophenolase activity) and the subsequent oxidation of 0-diphenols to o-quinones (diphenolase activity). Several studies have reported that this enzyme is involved in the degradation of natural phenols with complex structures, such as anthocyanins in strawberries and flavanols present in tea leaves. Several polyphenols... 

As mentioned previously, PPO shows two catalytic activities the conversion of monophenols into o-diphenols (monophenolase activity) and the oxidation to the corresponding o-quinones (diphenolase activity) (Fig. 4.2) (Sanchez-Ferrer and others, 1995). 

The monophenolase activity of PPO is generally defined as the first step in the melaniza-tion pathway and consists of the o-hydroxylation of the monophenol to odiphenol. This activity distinguishes PPO from other phenol-oxidizing enzymes, such as laccase and peroxidase, and is characterized by the following facts ... 

The close association of the two activities (monophenolase and diphenolase) is borne out by the reciprocal competitive inhibition pattern of monophenolic and diphenolic substrates and by coincidence of the various steps in the catalytic cycle. 

Monophenolase activity shows a characteristic lag period before the maximum velocity of the hydroxylation step is reached. The time required to reach the steady-state rate depends on several factors enzyme source concentration of monophenol ... 

Copper is part of several essential enzymes including tyrosinase (melanin production), dopamine beta-hydroxylase (catecholamine production), copper-zinc superoxide dismutase (free radical detoxification), and cytochrome oxidase and ceruloplasmin (iron conversion) (Aaseth and Norseth 1986). All terrestrial animals contain copper as a constituent of cytochrome c oxidase, monophenol oxidase, plasma monoamine oxidase, and copper protein complexes (Schroeder et al. 1966). Excess copper causes a variety of toxic effects, including altered permeability of cellular membranes. The primary target for free cupric ions in the cellular membranes are thiol groups that reduce cupric (Cu+2) to cuprous (Cu+1) upon simultaneous oxidation to disulfides in the membrane. Cuprous ions are reoxidized to Cu+2 in the presence of molecular oxygen molecular oxygen is thereby converted to the toxic superoxide radical O2, which induces lipoperoxidation (Aaseth and Norseth 1986). 

Noguchi A catalytic process for hydrogenating lignin to a mixture of monophenols. Invented in 1952 at the Noguchi Institute of Japan, but not commercialized because the yields were uneconomic. 

The efficacy of monophenols containing bulky substituents was first described in the patents from Mitsubishi Chemical Corporation [69] (42, Figure 8.17). They report high yields of aldehyde (> 90%) for the hydroformylation of 1-alkenes with high linearities. The l b ratios are generally above twenty using this ligand. 

Synonym(s) Benzenol, hydroxybenzene, monophenol, oxybenzene, phenyl alcohol, phenyl hydrate, phenyl hydroxide, phenylic acid, phenylic alcohol Lewis 1996... 

Besides the drugs discussed above, other phenyl-containing xenobiotics are also substrates of the epoxide-dihydrodiol pathway. Thus, a number of isomeric dichlorobiphenyls (10.23, m = 2, n = 0, or m = n = 1) were metabolized by rat liver microsomes to stable monophenols and dihydrodiols [84], Like for benzene, the second step in this pathway can be assumed to be a de-... 

Synonyms AI3-01814 AIDS-352 Baker s P and S liquid and ointment Benzenol BRN 0969616 Carbolic acid Carbolic oil Caswell No. 649 CCRIS 504 CRS EINECS 203-632-7 EPA pesticide chemical code 064001 FEMA No. 3223 Fenosmolin Fenosmoline Hydroxy-benzene IPH Izal Monohydroxybenzene Monophenol NA 2821 NCI-C50124 NSC 36808 Oxybenzene Phenic acid Phenic alcohol Phenol alcohol Phenyl hydrate Phenyl hydroxide Phenylic acid Phenylic alcohol RCRA waste number U188 UN 1671 UN 2312 UN 2821. 

The hemocyanlns which cooperatively bind dioxygen are found in two invertebrate phyla arthropod and mollusc. The mollusc hemocyanlns additionally exhibit catalase activity. Tyrosinase, which also reversibly binds dioxygen and dlsmutates peroxide, is a monooxygenase, using the dloxygen to hydroxylate monophenols to ortho-diphenols and to further oxidize this product to the quinone. Finally, the multicopper oxidases (laccase, ceruloplasmin and ascorbate oxidase) also contain coupled binuclear copper sites in combination with other copper centers and these catalyze the four electron reduction of dloxygen to water. 

Our earlier research on the coupled binuclear copper proteins generated a series of protein derivatives in which the active site was systematically varied and subjected to a variety of spectroscopic probes. These studies developed a Spectroscopically Effective Model for the oxyhemocyanin active slte.(l) The coupled binuclear copper active site in tyrosinase was farther shown to be extremely similar to that of the hemocyanlns with differences in reactivity correlating to active site accessibility, and to the monophenol coordinating directly to the copper(II) of the oxytyroslnase site.(2) These studies have been presented in a number of reviews.(3) In the first part of this chapter, we summarize some of our more recent results related to the unique spectral features of oxyhemocyanin, and use... 

These copper ion-dependent enzymes [EC 1.10.3.1] (also referred to as diphenol oxidases, O-diphenolase, phe-nolases, polyphenol oxidases, or tyrosinases) catalyze the reaction of two catechol molecules with dioxygen to produce two 1,2-benzoquinone and two water. A variety of substituted catechols can act as substrates. Many of the enzymes listed under this classification also catalyze a monophenol monooxygenase activity [/.c., EC 1.14.18.1]. See also Monophenol Monooxygenase Tyrosine Monooxygenase... 

This copper-dependent enzyme [EC 1.14.18.1] (also known as tyrosinase, phenolase, monophenol oxidase, and cresolase) catalyzes the reaction of L-tyrosine with L-dopa and dioxygen to produce L-dopa, dopaquinone, and water. This classification actually represents a set of copper proteins that also catalyze the reaction of catechol oxidase [EC 1.10.3.1] if only 1,2-benzenediols are available as substrates. 

MONOPHENOL MONOOXYGENASE NITRITE REDUCTASE PHOTOSYSTEM I QUERCETIN 2,3-DIOXYGENASE SUPEROXIDE DISMUTASES COPROPORPHYRINOGEN OXIDASE... 

ACTIN REGULATORY PROTEINS MONOMOLECULARITY Monomolecular surface coverage, BIOMINERALIZATION MONOPHENOL MONOOXYGENASE... 

MONOPHENOL MONOOXYGENASE NITRIC OXIDE SYNTHASE PEPTIDYL GLYCINE a-AMIDATING MONOOXYGENASE... 

Monophenol +V2O2 o-diphenol o-Diphenol +V2O2 o-quinone + H2O... 

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