| [PMID]: | 28701464 |
| [Au] Autor: | Johnson KM; Phan TTN; Albertolle ME; Guengerich FP |
| [Ad] Endereço: | From the Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0146. |
| [Ti] Título: | Human mitochondrial cytochrome P450 27C1 is localized in skin and preferentially desaturates -retinol to 3,4-dehydroretinol. |
| [So] Source: | J Biol Chem;292(33):13672-13687, 2017 Aug 18. |
| [Is] ISSN: | 1083-351X |
| [Cp] País de publicação: | United States |
| [La] Idioma: | eng |
| [Ab] Resumo: | Recently, zebrafish and human cytochrome P450 (P450) 27C1 enzymes have been shown to be retinoid 3,4-desaturases. The enzyme is unusual among mammalian P450s in that the predominant oxidation is a desaturation and in that hydroxylation represents only a minor pathway. We show by proteomic analysis that P450 27C1 is localized to human skin, with two proteins of different sizes present, one being a cleavage product of the full-length form. P450 27C1 oxidized all- -retinol to 3,4-dehydroretinol, 4-hydroxy (OH) retinol, and 3-OH retinol in a 100:3:2 ratio. Neither 3-OH nor 4-OH retinol was an intermediate in desaturation. No kinetic burst was observed in the steady state; neither the rate of substrate binding nor product release was rate-limiting. Ferric P450 27C1 reduction by adrenodoxin was 3-fold faster in the presence of the substrate and was ∼5-fold faster than the overall turnover. Kinetic isotope effects of 1.5-2.3 (on / ) were observed with 3,3-, 4,4-, and 3,3,4,4-deuterated retinol. Deuteration at C-4 produced a 4-fold increase in 3-hydroxylation due to metabolic switching, with no observable effect on 4-hydroxylation. Deuteration at C-3 produced a strong kinetic isotope effect for 3-hydroxylation but not 4-hydroxylation. Analysis of the products of deuterated retinol showed a lack of scrambling of a putative allylic radical at C-3 and C-4. We conclude that the most likely catalytic mechanism begins with abstraction of a hydrogen atom from C-4 (or possibly C-3) initiating the desaturation pathway, followed by a sequential abstraction of a hydrogen atom or proton-coupled electron transfer. Adrenodoxin reduction and hydrogen abstraction both contribute to rate limitation. |
| [Mh] Termos MeSH primário: |
Família 27 do Citocromo P450/metabolismo
Regulação Enzimológica da Expressão Gênica
Mitocôndrias/enzimologia
Pele/enzimologia
Vitamina A/análogos & derivados
Vitamina A/metabolismo
|
| [Mh] Termos MeSH secundário: |
Biocatálise
Família 27 do Citocromo P450/genética
Perfilação da Expressão Gênica
Seres Humanos
Hidrogenação
Hidroxilação
Isoenzimas/genética
Isoenzimas/metabolismo
Cinética
Estrutura Molecular
Especificidade de Órgãos
Oxirredução
Fragmentos de Peptídeos/genética
Fragmentos de Peptídeos/metabolismo
Proteólise
Proteômica/métodos
Estereoisomerismo
Especificidade por Substrato
Vitamina A/química
|
| [Pt] Tipo de publicação: | JOURNAL ARTICLE |
[Nm] Nome de substância:
| 0 (3,4-dehydroretinol); 0 (4-hydroxy-retinol); 0 (Isoenzymes); 0 (Peptide Fragments); 11103-57-4 (Vitamin A); 6890-93-3 (3-hydroxyretinol); EC 1.14.14.1 (CYP27C1 protein, human); EC 1.14.15.15 (Cytochrome P450 Family 27) |
| [Em] Mês de entrada: | 1709 |
| [Cu] Atualização por classe: | 170906 |
[Lr] Data última revisão:
| 170906 |
| [Sb] Subgrupo de revista: | IM |
| [Da] Data de entrada para processamento: | 170714 |
| [St] Status: | MEDLINE |
| [do] DOI: | 10.1074/jbc.M116.773937 |
| |
|
