Tyrosinases of diverse thermostabilities and their interconversion in Neurospora crassa

• Published in: Biochimica et biophysica acta Vol. 61; no. 1; pp. 108 - 120
• Main Authors: Fox, Allen S., Burnett, Jean B.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 09.07.1962
• Subjects: Catechol Oxidase; Monophenol Monooxygenase; Neurospora - metabolism; Neurospora crassa; OldMedline; Oxidoreductases - metabolism; l-dopa; PVP; NEUROSPORA/metabolism; OXIDASES/metabolism
• ISSN: 0926-6550; 0006-3002; 1878-2256
• DOI: 10.1016/0926-6550(62)90037-3

Continuous-flow paper electrophoresis separates the tyrosinase extracted from homocaryons of Neurospora crassa into 3 components (T 1, T 2, T 3). The Michaelis constants and relative turnover numbers of the 3 components are indistinguishable, but their thermostabilities differ. Further purification by ion-exchange chromatography yields no change in the electrophoretic, thermostability, or enzymic properties of the 3 tyrosinases. During the incubation of unfractionated extracts at low temperatures (5–25°), T 1 and T 2 disappear. The quantitative decrease in T 1 and T 2 is exactly compensated by an increase in T 3, suggesting a conversion of the 2 former into the latter. This conversion apparently requires the presence of an additional, non-dialyzable factor. It is suggested that these interconversions do not involve interstitial changes in primary structure and are under genetic control. The relationship of such a possibility to current theories of information transfer in protein synthesis is discussed.