Table 1 Analysis of the histidine in the second coordination sphere of AA9 LPMOs
PDB name | Microorganism | % Identity with TthLPMO9G | Position of histidine in Sequence | Discussed role | References |
|---|---|---|---|---|---|
TthLPMO9G | Thermothelomyces thermophilus | 100.0 | H140 | Mutagenesis of H140A that indicates: ↓monooxygenase/peroxygenase activity ↓peroxidase like activity ↓oxidase activity | Current & [30] |
4B5Q | Phanerodontia chrysosporium | 41.4 | H149 | MD simulation for cellulose recognition | [38] |
4D7U | Neurospora crassa | 36.8 | H155 | Direct interaction of a cellobiose dehydrogenase with the LPMO | [42] |
4EIR | Neurospora crassa | 36.9 | H157 | Destabilization of the glycosidic bond with the elimination reaction possibly catalyzed by a conserved third histidine Also identify the conserved second coordination shell residue His157 as the proton donor | |
4EIS | Neurospora crassa | 37.1 | H160 | Destabilization of the glycosidic bond with the elimination reaction possibly catalyzed by a conserved third histidine | [37] |
4UFV | Thermothelomyces thermophilus | 37.0 | H161 | Mutagenesis of H161A that indicates reduction in cellulose oxidation activity. Stabilizing bound oxygen and possible participation in proton transfer | [15] |
5ACF | Panus similis | 34.0 | H147 | QM/MM metadynamics simulations with doubly protonated His147 show that such reaction does not lead to a stable product, ruling out H2O2 formation via the proton transfer pathway Also is generally singly protonated thus cannot be a proton donor | |
5NNS | Heterobasidion irregulare | 34.5 | H159 | The active site was defined as His1, Pro79, His80, His159, Gln165, Tyr167, one crystallographic water molecule and the copper ion | [43] |
5O2X | Hypocrea jecorina | 32.6 | H-163 | H2O2 connects to amino acids in the second sphere. The amino acids closest to H2O2 are second-sphere glutamine and second-sphere histidine, with histidine being 2 Armstrong away from H2O2 | [36] |