Journal article
The catalytic effect of tyrosinase upon oxidation of 2-hydroxyestradiol in presence of catechol
Archives of biochemistry and biophysics, v 232(1), pp 189-196
1984
PMID: 6430238
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Abstract
The hydroxylating activity of mushroom tyrosinase has been utilized for over a decade in the preparation of 2-hydroxyestradiol from estradiol, yet this same enzyme is known to function as an oxidant of
o-dihydric compounds to the corresponding
o-quinones. It was questioned why catechol estrogens do not react further, particularly since the tyrosinase activity (hydroxylating) is exceeded many fold by the diphenol oxidase activity of the enzyme. This report describes that the catechol estrogen will react in presence of enzyme but only if catechol is also present. Diphenol oxidase activity was measured either by the polarographic oxygen-utilization technique or by changes in the absorption spectrum at 206 and 256 nm. The enzyme activity was standardized with catechol (
K
m
= 5.2 × 10
−4
M). The steroid did not react with the enzyme if catechol was absent. With catechol, the steroid reacted rapidly and completely (
K
m
= 4.2 × 10
−4
M). The consumption of oxygen with catechol and 2-hydroxyestradiol was additive and stoichiometric, 1 g-atom oxygen/mol of either substrate. Kinetic analysis shows that catechol functions as an activator of the tyrosinase.
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Details
- Title
- The catalytic effect of tyrosinase upon oxidation of 2-hydroxyestradiol in presence of catechol
- Creators
- Gert M. Jacobsohn - Hahnemann University HospitalMyra K. Jacobsohn - Arcadia University
- Publication Details
- Archives of biochemistry and biophysics, v 232(1), pp 189-196
- Publisher
- Elsevier
- Resource Type
- Journal article
- Language
- English
- Web of Science ID
- WOS:A1984SZ67600020
- Scopus ID
- 2-s2.0-0021129876
- Other Identifier
- 991019330810804721
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- Web of Science research areas
- Biochemistry & Molecular Biology
- Biophysics