title: Effect of acetonitrile on Cynara cardunculus L. cardosin A stability.
abstract: The kinetics of the structural changes affecting cardosin A, a plant aspartic proteinase (AP) from Cynara cardunculus L., in the presence of a mixture of acetonitrile (AN) in water (W) was studied. Incubation of cardosin A with 10% (v/v) AN resulted in a gradual increase in protein helicity, accompanied by changes in the tertiary structure, seen by changes in the intrinsic fluorescence of tryptophan. Differential scanning calorimetry (DSC) revealed that the temperature of denaturation of cardosin A decreased upon the addition of AN. With longer incubation times, the small chain of cardosin A denatured completely, consequent exposure of the single tryptophan residue accounting well for the observed spectral shift intrinsic fluorescence of the protein. Enzymatic activity assays demonstrated that the kinetically determined unfolding of the small chain of cardosin A does not result in loss of the activity of this enzyme.
authors.affiliation: Departamento de Bioquímica y Biología Molecular, Universidad de Salamanca, Salamanca, Spain.
authors.forename: Anna V
authors.initials: AV
authors.lastname: Shnyrova
authors.forename: Claudia S
authors.initials: CS
authors.lastname: Oliveira
authors.forename: Ana C
authors.initials: AC
authors.lastname: Sarmento
authors.forename: Marlene T
authors.initials: MT
authors.lastname: Barros
authors.forename: Galina G
authors.initials: GG
authors.lastname: Zhadan
authors.forename: Manuel G
authors.initials: MG
authors.lastname: Roig
authors.forename: Valery L
authors.initials: VL
authors.lastname: Shnyrov
mesh_terms: D000097:Acetonitriles / Q000494:pharmacology*; D016282:Aspartic Acid Endopeptidases / Q000737:chemistry* / Q000378:metabolism; D002152:Calorimetry, Differential Scanning; D002942:Circular Dichroism; D031942:Cynara / Q000201:enzymology*; D004795:Enzyme Stability / Q000187:drug effects; D007700:Kinetics; D010940:Plant Proteins / Q000737:chemistry* / Q000378:metabolism; D011487:Protein Conformation / Q000187:drug effects; D011489:Protein Denaturation / Q000187:drug effects; D013050:Spectrometry, Fluorescence; D013816:Thermodynamics; D014364:Tryptophan / Q000737:chemistry
chemical_list: D000097:Acetonitriles; D010940:Plant Proteins; D014364:Tryptophan; D016282:Aspartic Acid Endopeptidases; C097455:aspartic proteinases, Cynara cardunculus; C032159:acetonitrile