Thermodynamics of the helix-coil transition: Binding of S15 and a hybrid sequence, disulfide stabilized peptide to the S-protein

• Tipo: Artigo em Revista Científica Internacional
• Data: 2001

Autores

Bastos, M (Autor) FCUP; Pease, JHB (Autor) Outra; Wemmer, DE (Autor) Outra; Murphy, KP (Autor) Outra; Connelly, PR (Autor) Outra

Revista

Título: Proteins: Structure, Function and Genetics

Vol. 42

Páginas: 523-530

ISSN: 0887-3585

Editora: Wiley-Blackwell

Indexação

ISI Web of Knowledge - 10 Citações

Scopus - 9 Citações

Classificação Científica

FOS: Ciências exactas e naturais > Ciências biológicas

Outras Informações

ID Authenticus: P-000-WB0

DOI: 10.1002/1097-0134(20010301)42:4<523::aid-prot100>3.0.co;2-b

Abstract (EN): Pancreatic ribonuclease A may be cleaved to produce two fragments: the S-peptide (residues 1-20) and the S-protein (residues 21-124), The S-peptide, or a truncated version designated as the S15 peptide (residues 1-15), combines with the S-protein to produce catalytically active complexes. The conformation of these peptides and many of their analogues is predominantly random coil at room temperature; however, they populate a significant fraction of helical form at low temperature under certain solution conditions. Moreover, they adopt a helical conformation when bound to the S-protein. A hybrid sequence, disulfide-stabilized peptide (ApaS-25), designed to stabilize the helical structure of the S-peptide in solution, also combines with the S-protein to yield a catalytically active complex. We have performed high-precision titration microcalorimetric measurements to determine the free energy, enthalpy, entropy, and heat capacity changes for the binding of ApaS-25 to S-protein within the temperature range 5-25 degreesC. The thermodynamic parameters for both the complex formation reactions and the helix-to-coil transition also were calculated, using a structure-based approach, by calculating changes in accessible surface area and using published empirical parameters. A simple thermodynamic model is presented in an attempt to account for the differences between the binding of ApaS-25 and the S-peptide, From this model, the thermodynamic parameters of the helix-to-coil transition of S15 can be calculated. (C) 2001 Wiley-Liss, Inc.

Idioma: Inglês

Tipo (Avaliação Docente): Científica

Nº de páginas: 8