title: Breakdown of albumin and haemalbumin by the cysteine protease interpain A, an albuminase of Prevotella intermedia.
abstract: BACKGROUND
  Prevotella intermedia is a Gram-negative black-pigmenting oral anaerobe associated with periodontitis in humans, and has a haem requirement for growth, survival and virulence. It produces an iron porphyrin-containing pigment comprising monomeric iron (III) protoporphyrin IX (Fe(III)PPIX.OH; haematin). The bacterium expresses a 90-kDa cysteine protease termed interpain A (InpA) which both oxidizes and subsequently degrades haemoglobin, releasing haem. However, it is not known whether the enzyme may play a role in degrading other haem-carrying plasma proteins present in the gingival sulcus or periodontal pocket from which to derive haem. This study evaluated the ability of InpA to degrade apo- and haem-complexed albumin.
  
  
  RESULTS
  Albumin breakdown was examined over a range of pH and in the presence of reducing agent; conditions which prevail in sub- and supra-gingival plaque. InpA digested haemalbumin more efficiently than apoalbumin, especially under reducing conditions at pH 7.5. Under these conditions InpA was able to substantially degrade the albumin component of whole human plasma.
  
  
  CONCLUSIONS
  The data point to InpA as an efficient "albuminase" with the ability to degrade the minor fraction of haem-bound albumin in plasma. InpA may thus contribute significantly to haem acquisition by P. intermedia under conditions of low redox potential and higher pH in the inflamed gingival crevice and diseased periodontal pocket where haem availability is tightly controlled by the host.
authors.affiliation: Department of Biochemistry, Institute of Integrative Biology, The University of Liverpool, Crown Street, Liverpool, L69 7ZB, UK. bs0u4193@liv.ac.uk.
authors.forename: Dominic P
authors.initials: DP
authors.lastname: Byrne
authors.affiliation: Department of Biological Sciences, California State University Long Beach, 1250 Bellflower Blvd., Long Beach, California, 90840, USA. Surya.manandhar@csulb.edu.
authors.forename: Surya P
authors.initials: SP
authors.lastname: Manandhar
authors.affiliation: Malopolska Centre of Biotechnology and Department of Microbiology, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Gronostajowa 7, Krakow, 30-387, Poland. jan.potempa@louisville.edu.|Department of Oral Immunology and Infectious Diseases, University of Louisville School of Dentistry, 501 S. Preston St., Louisville, KY, 40202, USA. jan.potempa@louisville.edu.
authors.forename: Jan
authors.initials: J
authors.lastname: Potempa
authors.affiliation: The University of Liverpool, School of Dentistry, Daulby Street, Liverpool, L69 3GN, UK. josmall@liv.ac.uk.
authors.forename: John W
authors.initials: JW
authors.lastname: Smalley
mesh_terms: D000418:Albumins / Q000378:metabolism*; D057056:Cysteine Proteases / Q000378:metabolism*; D006418:Heme / Q000378:metabolism*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D018713:Prevotella intermedia / Q000201:enzymology*
chemical_list: D000418:Albumins; D006418:Heme; D057056:Cysteine Proteases