Low pH crystal structure of glycosylated lignin peroxidase from Phanerochaete chrysosporium at 2.5 A resolution.

The heme-containing glycoprotein lignin peroxidase (pI 4.15) has been crystallized at pH 4.0. The structure of the peroxidase from the orthorhombic crystals has been determined by multiple isomorphous replacement. The model comprises all 343 amino acids, one heme molecule, and three sugar residues. It has been refined to an R-factor of 20.3%. The chain fold of residues 15 to 275 is in general similar to those of cytochrome c peroxidase. Despite binding of the heme to the same region and a similar arrangement of the proximal and distal histidine as in cytochrome c peroxidase a significantly larger distance of the iron ion to the proximal histidine is observed. Distinct electron density extending from Asn-257 and at the distal side of the heme indicates ordered sugar residues in the crystal.