title: Mechanism of methaemoglobin breakdown by the lysine-specific gingipain of the periodontal pathogen Porphyromonas gingivalis.
abstract: Abstract The R- and K-gingipain proteases of Porphyromonas gingivalis are involved in proteolysis of haemoglobin from which the defensive dimeric haem pigment is formed. Whilst oxyhaemoglobin is refractory towards K-gingipain, methaemoglobin is rapidly degraded. Ligation of methaemoglobin with N3-, which effectively blocks haem dissociation from the protein, prevented haemoglobin breakdown. Haem-free globin was rapidly degraded by K-gingipain. These data emphasise the need for haemoglobin oxidation which encourages haem dissociation and makes the haem-free globin susceptible to proteolytic attack.
authors: Unit of Plaque-Related Diseases, School of Dental Science, The University of Liverpool, Liverpool L69 3GN, UK. josmall@liv.ac.uk
authors: John W
authors: JW
authors: Smalley
authors: Andrew J
authors: AJ
authors: Birss
authors: Borys
authors: B
authors: Szmigielski
authors: Jan
authors: J
authors: Potempa
mesh_terms: D018829:Adhesins, Bacterial / Q000378:metabolism*; D000818:Animals; D003546:Cysteine Endopeptidases / Q000378:metabolism*; D000080867:Gingipain Cysteine Endopeptidases; D006736:Horses; D008024:Ligands; D008706:Methemoglobin / Q000031:analogs & derivatives / Q000378:metabolism*; D016966:Porphyromonas gingivalis / Q000201:enzymology*
chemical_list: D018829:Adhesins, Bacterial; D000080867:Gingipain Cysteine Endopeptidases; D008024:Ligands; C029387:methemoglobin azide; D008706:Methemoglobin; D003546:Cysteine Endopeptidases