title: Raman and infrared studies on the conformation of porcine pancreatic and Crotalus durissus terrificus phospholipases A2.
abstract: Raman and infrared spectroscopies were used to investigate conformational features of Crotalus durissus terrificus and porcine pancreatic phospholipases A2, as well as the proenzyme of the latter. The results indicate that conformational changes occur for the phospholipase molecules as a consequence of different experimental conditions such as change of physical state, presence of certain ionic species and interaction with a model substrate analog. Amorphous and crystalline solid phospholipase present discrepant conformational features. Conformational transitions were detected for the pancreatic zymogen----phospholipase A2 transformation and different secondary contents were observed for a toxic and a nontoxic form of the phospholipase molecule. All those structural changes have been shown to involve primarily the architecture of the polypeptide backbone rather than the conformation of amino acid residue side-chains. Disulfide bridges have shown consistently a gauche-gauche-gauche geometry which has not been disturbed by any of the experimental conditions employed. The external occurrence of tryptophan residues has been a common feature for the systems assayed, as well as the predominant localization of tyrosine residues in hydrophilic environment, probably at the molecular surface.
authors.affiliation: Instituto de Química, Universidade de São Paulo, Brazil.
authors.forename: E P
authors.initials: EP
authors.lastname: Arêas
authors.forename: C J
authors.initials: CJ
authors.lastname: Laure
authors.forename: N
authors.initials: N
authors.lastname: Gabilan
authors.forename: P S
authors.initials: PS
authors.lastname: Araujo
authors.forename: Y
authors.initials: Y
authors.lastname: Kawano
mesh_terms: D000818:Animals; D003435:Crotalid Venoms; D004220:Disulfides / Q000032:analysis; D006863:Hydrogen-Ion Concentration; D010179:Pancreas / Q000201:enzymology*; D010740:Phospholipases; D010741:Phospholipases A; D054467:Phospholipases A2; D011487:Protein Conformation; D012967:Sodium Dodecyl Sulfate; D013055:Spectrophotometry, Infrared; D013059:Spectrum Analysis, Raman; D013552:Swine; D014364:Tryptophan / Q000032:analysis; D014443:Tyrosine / Q000032:analysis
chemical_list: D003435:Crotalid Venoms; D004220:Disulfides; D012967:Sodium Dodecyl Sulfate; D014443:Tyrosine; D014364:Tryptophan; D010740:Phospholipases; D010741:Phospholipases A; D054467:Phospholipases A2