OXYGEN TRANSFER AND ELECTRON TRANSPORT BY THE PHENOLASE COMPLEX¹

Melanins: Skin Pigments and Much More—Types, Structural Models, Biological Functions, and Formation Routes

“…All phenolases are mixed oxygenases, as only one atom of the atmospheric oxygen is incorporated to the phenolic substrates [237], but the system shows several forms in different organisms. Phenolases are always copper-proteins able to oxidize phenols (monophenols, o-diphenols, and p-diphenols).…”

Mechanistic studies of tyrosinase suicide inactivation

“…Tyrosinase is unusual in that it exhibits two catalytic functions: (a) oxygenase activity ('cresolase' action) in which monohydric phenols have oxygen substituted at the 2-position giving an ortho-quinone (Scheme 1); 3,4 and (b) oxidase activity ('catecholase' action) 5 in which a catechol is oxidised to an ortho-quinone (Scheme 1). One of the characteristics of in vitro oxidation of tyrosine 4 is a 'lag period'.…”

Tryptophan, Oxygen, and Sleep

“…As I was completing a manuscript and about to mail it to the Journal of Biological Chemistry, Alan Mehler told me that Howard Mason and his associates in Oregon had just demonstrated that a mushroom phenolase complex could catalyze the incorporation of one atom of molecular oxygen into 3,4-dimethylphenol to form 4,5-dimeth ylcatechol. Mason's paper (14), along with my communication to the Journal of the American Chemical Society (15) , appeared in 1955 as "Letters to the Editor." These findings, along with subsequent work by Konrad Bloch and others, established that "oxygen fixation" did indeed occur in biological systems, and the concept of "biological oxygenation" was introduced.…”