| Autor: |
V A, Sukhanov, V L, D'iakov, V V, Lalaev, A V, Iakh'iaev |
| Rok vydání: |
1991 |
| Předmět: |
|
| Zdroj: |
Biokhimiia (Moscow, Russia). 56(6) |
| ISSN: |
0320-9725 |
| Popis: |
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. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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