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Published August 1, 1956 | public
Journal Article Open

Studies of tyrosinase production by a heterocaryon of Neurospora


The tyrosinase of Neurospora crassa exists in two forms that differ in their thermostability.(1) This difference is inherited in a simple Mendelian way, the stable form of the enzyme being determined by a gene, Ts, and the labile form by its allele, TL. The locus is on the right arm of the mating-type chromosome, 18 map units (uncorrected) distal to adenineless-35203 but proximal to albino-15300. As far as is known at present, the only other property in which the two forms of the enzyme differ is in the activation energy of thermal inactivation, which appears to be higher for the thermolabile form.(2) Measurements of several functional properties, including Michaelis constants for two substrates and relative turnover numbers, have not shown any significant difference between the two enzymes.(2)

Additional Information

Copyright © 1956 by the National Academy of Sciences. Communicated by G. W. Beadle, May 31, 1956. We wish to acknowledge the invaluable assistance of Mrs. Anne Kilim Nazarian. Dr. R. R. Jennings participated in the mapping of the T-locus. We are indebted to Dr. Dan Lewis, of the John Innes Horticultural Institution, for stimulating discussions. Aided by grants from the Nutrition Foundation, Inc., and the Atomic Energy Commission (AT-04-3-41).


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