Thermodynamic and Kinetic Analysis of Peptides Derived from CapZ, NDR, p53, HDM2, and HDM4 Binding to Human S100B

• Published in: Biochemistry (Easton) Vol. 51; no. 36; pp. 7189 - 7201
• Main Authors: Wafer, Lucas N, Streicher, Werner W, McCallum, Scott A, Makhatadze, George I
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 11-09-2012
• Subjects: Amino Acid Sequence; CapZ Actin Capping Protein - chemistry; CapZ Actin Capping Protein - metabolism; Cell Cycle Proteins; Humans; Kinetics; Models, Molecular; Molecular Sequence Data; Nerve Growth Factors - chemistry; Nerve Growth Factors - metabolism; Nuclear Proteins - chemistry; Nuclear Proteins - metabolism; Peptide Fragments - chemistry; Peptide Fragments - metabolism; Protein Binding; Protein Serine-Threonine Kinases - chemistry; Protein Serine-Threonine Kinases - metabolism; Proto-Oncogene Proteins - chemistry; Proto-Oncogene Proteins - metabolism; Proto-Oncogene Proteins c-mdm2 - chemistry; Proto-Oncogene Proteins c-mdm2 - metabolism; S100 Calcium Binding Protein beta Subunit; S100 Proteins - chemistry; S100 Proteins - metabolism; Thermodynamics; Tumor Suppressor Protein p53 - chemistry; Tumor Suppressor Protein p53 - metabolism
• ISSN: 0006-2960; 1520-4995; 1520-4995
• DOI: 10.1021/bi300865g

S100B is a member of the S100 subfamily of EF-hand proteins that has been implicated in malignant melanoma and neurodegenerative conditions such as Alzheimer’s disease and Parkinson’s disease. Calcium-induced conformational changes expose a hydrophobic binding cleft, facilitating interactions with a wide variety of nuclear, cytoplasmic, and extracellular target proteins. Previously, peptides derived from CapZ, p53, NDR, HDM2, and HDM4 have been shown to interact with S100B in a calcium-dependent manner. However, the thermodynamic and kinetic basis of these interactions remains largely unknown. To gain further insight, we screened these peptides against the S100B protein using isothermal titration calorimetry and nuclear magnetic resonance. All peptides were found to have binding affinities in the low micromolar to nanomolar range. Binding-induced changes in the line shapes of S100B backbone 1H and 15N resonances were monitored to obtain the dissociation constants and the kinetic binding parameters. The large microscopic K on rate constants observed in this study (≥1 × 107 M–1 s–1) suggest that S100B utilizes a “fly casting mechanism” in the recognition of these peptide targets.