Tyrosinase is a type 3 copper enzyme that catalyzes theortho-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-termini [jrPPO1(Asp101–Pro444) andjrPPO1(Asp101–Arg445)] were obtained. The most abundant formjrPPO1(Asp101–Arg445), as described in Zekiriet al.[Phytochemistry(2014),101, 5–15], was crystallized, resulting in crystals that belonged to space groupC121, with unit-cell parametersa= 115.56,b= 91.90,c= 86.87 Å, α = 90, β = 130.186, γ = 90°, and diffracted to 2.39 Å resolution. Crystals were only obtained from solutions containing at least 30% polyethylene glycol 5000 monomethyl ether in a close-to-neutral pH range.
Comparison of crystal structures of human type 3 3α-hydroxysteroid dehydrogenase reveals an “induced-fit” mechanism and a conserved basic motif involved in the binding of androgen