7y8c

Publication Abstract from PubMed

CotA laccases are multicopper oxidases known for promiscuously oxidizing a broad range of substrates. However, studying substrate promiscuity is limited by the complexity of electron transfer (ET) between substrates and laccases. Here, a systematic analysis of factors affecting ET including electron donor acceptor coupling (Eta(DA)), driving force (DeltaG) and reorganization energy (lambda) was done. Catalysis rates of syringic acid (SA), syringaldehyde (SAD) and acetosyringone (AS) (kcat(SAD) > kcat(SA) > kcat(AS)) are not entirely dependent on the ability to form phenol radicals indicated by DeltaG and lambda calculated by Density Functional Theory (SA < SAD approximately AS). In determined CotA/SA and CotA/SAD structures, SA and SAD bound at 3.9 and 3.7 A away from T1 Cu coordinating His419 ensuring a similar Eta(DA). Abilities of substrate to form phenol radicals could mainly account for difference between kcat(SAD) and kcat(SA). Furthermore, substrate pocket is solvent exposed at the para site of substrate's phenol hydroxyl, which would destabilize binding of AS in the same orientation and position resulting in low kcat. Our results indicated shallow partially covered binding site with propensity of amino acids distribution might help CotA discriminate lignin-phenol derivatives. These findings give new insights for developing specific catalysts for industrial application.

Molecular insights into substrate promiscuity of CotA laccase catalyzing lignin-phenol derivatives.,Li J, Liu Z, Zhao J, Wang G, Xie T Int J Biol Macromol. 2024 Jan;256(Pt 2):128487. doi: , 10.1016/j.ijbiomac.2023.128487. Epub 2023 Dec 1. PMID:38042324^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.