Título: The oxidative biodegradation of lignin as seen from the "enzyme side"
Autor: Sáez-Jiménez, Verónica; Rencoret, Jorge; Gutiérrez Suárez, Ana; Ruiz-Dueñas, F. J.; Martínez, Ángel T.
Resumen: Methodological limitations difficult estimation of lignin oxidation rates by Iigninolytic peroxidases. Here, lignin oxidation was seen from the "enzyme side" by estimating the reduction rates of H202 activated peroxidase compounds I and 11, using rapid spectrophotometry. Removal of Trp164 in versatile peroxidase resulted in 4-100 fold slower rate-limiting compound-II reduction by watersoluble sulfonated lignins. Moreover, when methylated lignosulfonates were used, negligible transfer was found, confirming that residual reduction by native lignin was due to its phenolic moiety. In agreement with the transient-state kinetic data, low or null structural modification of lignin was found (by NMR) during steady-state treatment with the W164S variant compared with native VP. Similar results were obtained with lignin peroxidase. Therefore, we demonstrate for the first time that the surface tryptophan conserved in most LiPs and VPs is strictly required for oxidation of the nonphenolic moiety, which represents the major and more recalcitrant part of the lignin polymer.
Descripción: Comunicación oral presentada en Lignobiotech 2018 - the 5th Symposium of Biotechnology Applied to Lignocelluloses 29 ago-1 sept (2018) Helsinki, Finlandia
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