[Heterogeneity of tyrosinases isolated from rat skin, normal human skin, and human melanoma tumors].
An electrophoretically homogeneous preparation of tyrosinase (Mr = 61 kDa) was isolated from rat skin. The purification procedure which consisted in chromatographic separation of Triton X-100-solubilized proteins included four main steps, namely: gel filtration, anion-exchange chromatography and two consecutive affinity chromatography steps. Isoelectrofocusing revealed the presence of 9 isoforms possessing an L-DOPA oxidase activity, of which proteins with pI of 4.26 and 4.33 were the major ones. The specific activity of the preparation was 43 nmol/min/mg of protein. Human skin epidermis was practically devoid of the L-DOPA-oxidase activity which was due not only to the absence of tyrosinase but also to the presence of a large amount of a 66 kDa protein able to inhibit the oxidation of L-DOPA to DOPA-chrom. The tyrosinase preparation from human melanoma consisted, predominantly, of two isoforms (48 and 69 kDa) which upon isoelectrofocusing displayed a high heterogeneity at pH around 3-5. The specific activity of the melanoma preparation markedly exceeded that of normal skin tyrosinase and was equal to 290 nmol/min/mg of protein.
V A
VA
Sukhanov
V L
VL
D'iakov
V V
VV
Lalaev
A V
AV
Iakh''iaev
D000818:Animals; D015153:Blotting, Western; D002853:Chromatography, Liquid; D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D007525:Isoelectric Focusing; D007527:Isoenzymes / Q000302:isolation & purification* / Q000378:metabolism; D007700:Kinetics; D007980:Levodopa / Q000378:metabolism; D008545:Melanoma / Q000201:enzymology*; D014442:Monophenol Monooxygenase / Q000302:isolation & purification* / Q000378:metabolism; D010084:Oxidation-Reduction; D051381:Rats; D012867:Skin / Q000201:enzymology*; D012878:Skin Neoplasms / Q000201:enzymology*
D007527:Isoenzymes; D007980:Levodopa; D014442:Monophenol Monooxygenase
Geterogennost' preparatov tirozinazy, vydelennykh iz kozhi krys, kozyi i melanomnykh opukholeĭ cheloveka.