title: Haemophilus paragallinarum secretes metalloproteases.
abstract: Haemophilus paragallinarum secretes metalloproteases into different culture media lacking serum. Secreted proteins, concentrated by precipitation with 70% ammonium sulphate ((NH(4))(2)SO(4)) or methanol, displayed proteolytic activity at >100 kDa molecular mass in 10% polyacrylamide gels co-polymerized with porcine gelatin (0.1%). They were active in a broad pH range (4-9); pH 7.5 being the optimum. Protease activity was inhibited by 20 mmol EDTA/L and reactivated by calcium. The proteolytic activity was heat-stable at 40, 50, and 60 degrees C, but its activity diminished at 70 degrees C or higher. Secreted proteins partially degraded chicken immunoglobulin G (IgG) and cross-reacted with a polyclonal serum against a high molecular mass protease secreted by Actinobacillus pleuropneumoniae. Extracellular proteases could play a role in infectious coryza caused by H. paragallinarum.
authors.affiliation: Carrera de Biología, Facultad de Estudios Superiores Iztacala, UNAM, Los Reyes Iztacala, Tlalnepantla, Mexico.
authors.forename: P C
authors.initials: PC
authors.lastname: Rivero-García
authors.forename: C Vázquez
authors.initials: CV
authors.lastname: Cruz
authors.forename: P Sánchez
authors.initials: PS
authors.lastname: Alonso
authors.forename: S
authors.initials: S
authors.lastname: Vaca
authors.forename: E
authors.initials: E
authors.lastname: Negrete-Abascal
mesh_terms: D000818:Animals; D002645:Chickens; D003470:Culture Media; D006192:Haemophilus Infections / Q000382:microbiology / Q000662:veterinary; D044134:Haemophilus paragallinarum / Q000201:enzymology* / Q000254:growth & development / Q000472:pathogenicity; D007074:Immunoglobulin G / Q000378:metabolism; D045726:Metalloproteases / Q000737:chemistry / Q000378:metabolism*; D011201:Poultry Diseases / Q000382:microbiology
chemical_list: D003470:Culture Media; D007074:Immunoglobulin G; D045726:Metalloproteases