title: Comparative study of mature and zymogen mite cysteine protease stability and pH unfolding.
abstract: BACKGROUND
  Papain-like proteases (CA1) are synthesized as inactive precursors carrying an N-terminal propeptide, which is further removed under acidic conditions to generate active enzymes.
  
  
  METHODS
  To have a better insight into the mechanism of activation of this protease family, we compared the pH unfolding of the zymogen and the mature form of the mite cysteine protease Der p 1.
  
  
  RESULTS
  We showed that the presence of the propeptide does not significantly influence the pH-induced unfolding of the catalytic domain but does affect its fluorescence properties by modifying the exposure of the tryptophan 192 to the solvent. In addition, we demonstrated that the propeptide displays weaker pH stability than the protease domain confirming that the unfolding of the propeptide is the key event in the activation process of the zymogen.
  
  
  CONCLUSIONS
  Finally, we show, using thermal denaturation and enzymatic activity measurements, that whatever the pH value, the propeptide does not stabilize the structure of the catalytic domain but very interestingly, prevents its autolysis.
authors.affiliation: Macromolécules Biologiques, Centre d'Ingénierie des Protéines, Université de Liège, Institut de Chimie B6, Sart Tilman Liège B-4000, Belgique.
authors.forename: Andy
authors.initials: A
authors.lastname: Chevigné
authors.forename: Marie-Eve
authors.initials: ME
authors.lastname: Dumez
authors.forename: Mireille
authors.initials: M
authors.lastname: Dumoulin
authors.forename: André
authors.initials: A
authors.lastname: Matagne
authors.forename: Alain
authors.initials: A
authors.lastname: Jacquet
authors.forename: Moreno
authors.initials: M
authors.lastname: Galleni
mesh_terms: D000818:Animals; D039741:Antigens, Dermatophagoides / Q000737:chemistry*; D060829:Arthropod Proteins; D003546:Cysteine Endopeptidases; D057056:Cysteine Proteases / Q000737:chemistry*; D004792:Enzyme Precursors / Q000737:chemistry*; D004795:Enzyme Stability; D006863:Hydrogen-Ion Concentration; D011489:Protein Denaturation; D017510:Protein Folding; D017434:Protein Structure, Tertiary; D039981:Pyroglyphidae / Q000201:enzymology*
chemical_list: D039741:Antigens, Dermatophagoides; D060829:Arthropod Proteins; D004792:Enzyme Precursors; D057056:Cysteine Proteases; D003546:Cysteine Endopeptidases; C451162:Dermatophagoides pteronyssinus antigen p 1