Tyrosinase as glycoprotein

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Abstract
Purified tyrosinase T1 was incubated with neuraminidase. The catalytic activity of tyrosinase was essentially retained, after this treatment. The tyrosinase band (Dopa stained) was transformed into a new less anodic form, similar to tyrosinase T2, on disc electrophoresis. The band of protein was also converted to the same position as the Dopa stained. The other hand, the only one PAS stained band of native tyrosinase T1 was splitted into the three slower-moving bands. One was consistent with Dopa and protein stained bands. The other two were much moro slower than the former band and completely free of peptide and enzymic activity. The PAS-densitometric value of native tyrosinase T1 was almost equal to those of three separated bands in total. These results suggest that mammalian tyrosinase is a kind of glycoprotein. Bei Inkubation von gereinigter Tyrosinase T1 mit Neuraminidase blieb die katalytische Aktivität von Tyrosinase im wesentlichen erhalten. In der Disc-Elektrophorese erschien das Tyrosinaseband (bei Dopa-Färbung) als neue, weniger anodische Form, ähnlich der Tyrosinase T2. Andererseits erschien das einzige PAS-gefärbte Band der nativen Tyrosinase T1 in Form von drei langsam wandernden Bändern. Eines davon entsprach Dopa und proteinhaltigen Bändern. Die beiden anderen wanderten wesentlich langsamer und waren frei von Peptiden und enzymatischer Aktivität. Die PAS-Dichtemeßwerte der nativen Tyrosinase T1 waren fast so groß wie die zusammengenommenen Werte der einzelnen Banden. Die Ergebnisse lassen vermuten, daß die Säugetier-Tyrosinase eine Art Glykoprotein darstellt.