Background: o-Aminophenols have been long recognised as tyrosinase substrates. However their exact mode of interaction with the enzyme's active site is unclear. Properly vic-substituted o-aminophenols could help gain some insight into tyrosinase catalytic mechanism. Methods: Eight vic-substituted o-aminophenols belonging to two isomeric series were systematically evaluated as tyrosinase substrates and/or activators and/or inhibitors, by means of spectrophotometric techniques and HPLC-MS analysis. Some relevant kinetic parameters have also been obtained. Results: Four o-aminophenolic compounds derived from 3-hydroxyorthanilic acid (2-amino-3-hydroxybenzenesulfonic acid) and their four counterparts derived from the isomeric 2-hydroxymetanilic acid (3-amino-2- hydroxybenzenesulfonic acid) were synthesised and tested as putative substrates for mushroom tyrosinase. While the hydroxyorthanilic derivatives were quite inactive as both substrates and inhibitors, the hydroxymetanilic compounds on the contrary all acted as substrates for the enzyme, which oxidised them to the corresponding phenoxazinone derivatives. General significance: Based on the available structures of the active sites of tyrosinases, the different affinities of the fourmetanilic derivatives for the enzyme, and their oxidation rates,we propose a new hypothesis regarding the interaction between o-aminophenols and the active site of tyrosinase that is in agreement with the obtained experimental results.

Structure-activity relationships of some amino-hydroxy-benzenesulfonic acids and sulfonamides as tyrosinase substrates

RESCIGNO, ANTONIO;PADIGLIA, ALESSANDRA;SALIS, ANDREA;SANJUST, ENRICO
2011

Abstract

Background: o-Aminophenols have been long recognised as tyrosinase substrates. However their exact mode of interaction with the enzyme's active site is unclear. Properly vic-substituted o-aminophenols could help gain some insight into tyrosinase catalytic mechanism. Methods: Eight vic-substituted o-aminophenols belonging to two isomeric series were systematically evaluated as tyrosinase substrates and/or activators and/or inhibitors, by means of spectrophotometric techniques and HPLC-MS analysis. Some relevant kinetic parameters have also been obtained. Results: Four o-aminophenolic compounds derived from 3-hydroxyorthanilic acid (2-amino-3-hydroxybenzenesulfonic acid) and their four counterparts derived from the isomeric 2-hydroxymetanilic acid (3-amino-2- hydroxybenzenesulfonic acid) were synthesised and tested as putative substrates for mushroom tyrosinase. While the hydroxyorthanilic derivatives were quite inactive as both substrates and inhibitors, the hydroxymetanilic compounds on the contrary all acted as substrates for the enzyme, which oxidised them to the corresponding phenoxazinone derivatives. General significance: Based on the available structures of the active sites of tyrosinases, the different affinities of the fourmetanilic derivatives for the enzyme, and their oxidation rates,we propose a new hypothesis regarding the interaction between o-aminophenols and the active site of tyrosinase that is in agreement with the obtained experimental results.
Active site; Tyrosinase activity; Phenoxazinone
File in questo prodotto:
File Dimensione Formato  
BBA (2011) - Rescigno et al.pdf

Solo gestori archivio

Descrizione: Articolo principale
Tipologia: versione post-print
Dimensione 1.51 MB
Formato Adobe PDF
1.51 MB Adobe PDF   Visualizza/Apri   Richiedi una copia

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11584/41846
Citazioni
  • ???jsp.display-item.citation.pmc??? 2
  • Scopus 18
  • ???jsp.display-item.citation.isi??? 18
social impact