Manganese, Mn-dependent peroxidases, and the biodegradation of lignin

Participation of Mn(II) in the catalysis of laccase, manganese peroxidase and lignin peroxidase from Phlebia radiata

“…Although Mn(III)-lactate caused also a slow increase in absorbance at 310 nm, HPLC-analysis did not show any veratraldehyde formation. This indicates that chelated Mn(II1) was not able to oxidize veratryl alcohol directly, which is in contrast with previous data [26,27] but in accordance with the inability of Mn(II1) to oxidize methoxybenzenes of higher redox potential than 1.2 v [28].…”

“…The slow increase in absorbance observed at 310 nm with MnPI Mn(II)/H,O~/veratryl alcohol may have been due to Mn(II1) lactate absorbing at this wavelength [12]. MnP is reported to oxidize veratryl alcohol and other nonphenolic compounds in the presence of Mn(II), H202, and a thiol reductant, such as glutathione [26,29]. The reaction proceeds via the formation of a thiyl radical by Mn(II1) chelate, and the thiyl radical acts as an oxidant for non-phenols [29].…”

Stimulation of Mn peroxidase activity: a possible role for oxalate in lignin biodegradation.

“…The enzymes exhibit an absolute requirement for the transition metal Mn as a reducing substrate (12). The rate of catalysis is dependent on the presence of Mn chelators (7,12,13). Not surprisingly, the reactivity of transition metals is highly dependent on their chelation states.…”

“…Not surprisingly, the reactivity of transition metals is highly dependent on their chelation states. Past studies have shown that chelators affect not only the reaction of divalent Mn with Mn peroxidase (12) but also the reaction of trivalent Mn with its organic substrates (13). Due to the importance of chelators to Mn peroxidase action and due to the relative importance of this enzyme in lignin biodegradation (6), we investigated whether P. chrysosporium produces chelators that would stimulate Mn peroxidase.…”

Wood production, wood technology, and biotechnological impacts

“…MnP is the only fungal enzyme able to oxidise organic structures to carbon dioxide (CO 2 ), thus performing an enzymatic combustion , Hofrichter 2002. The oxidative ability of MnP can be enhanced by presence of additional co-oxidants such as unsaturated lipids and thiols (Forrester et al 1988, Wariishi et al 1989, van Aken et al 2000, Bermek et al 2002.…”