DSpace

Digital.CSIC > Ciencias Agrarias > Centro de Edafología y Biología Aplicada del Segura (CEBAS) > (CEBAS) Artículos >

Share

EndNote

Impact

Links

Closed Access item Effect of captopril on mushroom tyrosinase activity in vitro

Authors:Espín de Gea, Juan Carlos
Wichers, Harry J.
Keywords:Captopril, L-3,4-Dihydroxyphenylalanine, Inhibition, Irreversible, L -Tyrosine, Tyrosinase
Issue Date:12-Jan-2001
Publisher:Elsevier
Citation:Biochimica et Biophysica Acta (BBA)-Protein Structure and Molecular Enzymology 1544(1-2): 289-300 (2001)
Abstract:The study presented here demonstrates that the antihypertensive drug captopril ([2S]-N-[3-mercapto-2-methylpropionyl]- -proline) is an irreversible non-competitive inhibitor and an irreversible competitive inhibitor of the monophenolase and diphenolase activities of mushroom tyrosinase when -tyrosine and -DOPA were assayed spectrophotometrically in vitro, respectively. Captopril was rendered unstable by tyrosinase catalysis because of the interaction between the enzymatic-generated product (o-quinone) and captopril to give rise to a colourless conjugate. Therefore, captopril was able to prevent melanin formation. The spectrophotometric recordings of the inhibition of tyrosinase by captopril were characterised by the presence of a lag period prior to the attainment of an inhibited steady state rate. The lag period corresponded to the time in which captopril was reacting with the enzymatically generated o-quinone. Increasing captopril concentrations provoked longer lag periods as well as a concomitant decrease in the tyrosinase activity. Both lag period and steady state rate were dependent of captopril, substrate and tyrosinase concentrations. The inhibition of both monophenolase and diphenolase activities of tyrosinase by captopril showed positive kinetic co-operativity which arose from the protection of both substrate and o-quinone against inhibition by captopril. Inhibition experiments carried out using a latent mushroom tyrosinase demonstrated that captopril only bound the enzyme at its active site. The presence of copper ions only partially prevented but not reverted mushroom tyrosinase inhibition. This could be due to the formation of both copper-captopril complex and disulphide interchange reactions between captopril and cysteine rich domains at the active site of the enzyme.
Description:12 pages, 10 figures.
Publisher version (URL):http://dx.doi.org/10.1016/S0167-4838(00)00230-2
URI:http://hdl.handle.net/10261/18147
ISSN:0167-4889
???metadata.dc.identifier.doi???:10.1016/S0167-4838(00)00230-2
Appears in Collections:(CEBAS) Artículos

Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.