Abstract
Publisher Summary This chapter presents the assay, purification, and properties of tyrosinases from hamster melanoma. Tyrosinases catalyze the conversion of tyrosine to 3, 4-dihydroxyphenylalanine (dopa) and then to melanin. AH2 represents an electron donor. During the purification of the enzyme, after a soluble preparation has been obtained, the most convenient assay involves the oxidation of dopa and the measurement of the initial rate of formation of dopachrome as indicated by the change in absorbancy at 475 mμ. There is a constant rate of formation of dopachrome for the first 2 minutes, but the apparent rate then falls off as dopachrome itself is converted to other compounds. Another important assay is the measurement of tyrosine hydroxylation using 3, 5-3H-L-tyrosine, which leads to the formation of 3HOH. This method is used for measuring the activity of the homogenate, and, because of its increased sensitivity, it is generally the method of choice for the assay of low-activity samples. L-dopa is the best electron donor or cosubstrate for the tyrosine hydroxylation reaction of tyrosinase.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
