Methods for the preparation of 4-bromo-5-[2-(4-hydroxybenzyl)benzyl]-2methoxyphenol and 4-bromo-5-[4-(4-hydroxyphenyl)butyl]-2-methoxyphenol are described.

Tyrosinase, which usually catalyzes the conversion of o-diphenols to o-benzoquinones, catalyzed an unusual oxidative dimerization of 1,2-dehydro-N-acetyldopamine to a benzodioxan derivative. The identity of the product was confirmed by UV, IR spectra, and NMR studies. During the oxidation, generation of a transient reactive intermediate could be witnessed by its characteristic visible absorptio...

Abstraet--Sclerotized oothecae from four species of cockroaches, Periplaneta americana, P. fuliginosa, Blatta orientalis and Blattella germanica, were examined by solid-state 13C-nuclear magnetic resonance and chemical analyses. The oothecae were composed of protein, water, calcium oxalate, diphenolic compounds, lipid, and uric acid. Calcium oxalate was the major soluble component in egg cases ...

Most cloned and/or characterized plant polyphenol oxidases (PPOs) have catechol oxidase activity (i.e., they oxidize o-diphenols to o-quinones) and are localized or predicted to be localized to plastids. As a class, they have broad substrate specificity and are associated with browning of produce and other plant materials. Because PPOs are often induced by wounding or pathogen attack, they are ...

Tyrosinase is a type 3 copper enzyme that catalyzes the ortho-hydroxylation of monophenols to diphenols as well as their subsequent oxidation to quinones, which are precursors for the biosynthesis of melanins. The first plant tyrosinase from walnut leaves (Juglans regia) was purified to homogeneity and crystallized. During the purification, two forms of the enzyme differing only in their C-term...

Extracellular Neurospora laccase (p-diphenol:oxygen oxidoreductase; EC 1.10.3.2) has been purified to apparent homogeneity by classical purification techniques. The enzyme, which consists of mainly one form, has a molecular weight of 64,800 and contains 11% carbohydrate. The ultraviolet, visible, and electron paramagnetic resonance spectra indicate that both type I and type II copper are presen...

Polyphenol oxidase (PPO) (monophenol, o-diphenol: oxygen oxidoreductase; EC 1.14.18.1) is a binuclear copper-cluster-containing monooxygenase ubiquitously present in biological systems (1, 2). PPO may be distinguished from the related oxidase laccase [p-diphenol:oxygen oxidoreductase; EC 1.10.3.2] by its substrate specificity and the type and number of catalytic coppers. PPO catalyzes the oxida...

In order to prepare thermally stable isosorbide-derived thermoplastic polyurethane, the synthesis of two new chiral exo-exo configured diols, prepared from isosorbide, and two types of diphenols (bisphenol A and thiodiphenol) was described. The synthesis conditions were optimized under conventional heating and microwave irradiations. To prove their suitability in polymerization, these monomers ...

Monophenol monooxygenase (monophenol, dihydroxyphenylalanine:oxygen oxidoreductase EC 1.14.18.1) was studied in melanin-positive and melanin-negative mutants of Streptomyces lincolnensis NCIB 9413, varying in the lincomycin synthesizing ability. The activities of laccase and tyrosine phenol lyase (EC 4.1.99.2) are absent in this organism. The monophenol monooxygenase catalyzes hydroxylation of ...