P450 CYP17A1 Variant with a Disordered Proton Shuttle Assembly Retains Peroxo‐Mediated Lyase Efficiency
| Autor: | Stephen G. Sligar, Ilia G. Denisov, James R. Kincaid, Yilin Liu, Yelena V. Grinkova |
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| Rok vydání: | 2020 |
| Předmět: |
Stereochemistry
Mutant Lyases 010402 general chemistry 01 natural sciences Article Catalysis Hydroxylation chemistry.chemical_compound medicine Humans Threonine Lyase activity Progesterone Bond cleavage 010405 organic chemistry Chemistry Organic Chemistry Steroid 17-alpha-Hydroxylase General Chemistry Lyase 0104 chemical sciences CYP17A1 Pregnenolone Protons medicine.drug |
| Zdroj: | Chemistry |
| ISSN: | 1521-3765 0947-6539 |
| Popis: | Human cytochrome P450 CYP17A1 first catalyzes hydroxylation at the C17 position of either pregnenolone (PREG) or progesterone (PROG), and a subsequent C(17)–C(20) bond scission to produce dehydroepiandrosterone (DHEA) or androstenedione (AD). In the T306A mutant, replacement of the Threonine 306 alcohol functionality, essential for efficient proton delivery in the hydroxylase reaction, has only a small effect on the lyase activity. In this work, resonance Raman spectroscopy is employed to provide crucial structural insight, confirming that this mutant, with its disordered proton shuttle, fails to generate essential hydroxylase pathway intermediates, accounting for the loss in hydroxylase efficiency. Significantly, a corresponding spectroscopic study with the susceptible lyase substrate, 17-OH PREG, not only reveals an initially trapped peroxo-iron intermediate experiencing an H-bond interaction of the 17-OH group with the proximal oxygen of the Fe-O(p)-O(t) fragment, facilitating peroxo- attack on the C(20) carbon, but also unequivocally shows the presence of the subsequent hemiketal intermediate of the lyase reaction. |
| Databáze: | OpenAIRE |
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