PentUnFOLD

PentUnFOLD analyzes protein structural instability in intrinsically disordered proteins (IDPs) by applying physicochemical propensity scales and intraprotein contact analysis to identify secondary-structure transitions and their stability consequences.

Key Features:

• Physicochemical Basis: Uses novel propensity scales for disordered, nonstable, and stable elements of secondary structure derived from structural data focused on disordered middle sequence regions, excluding N- and C-terminal regions.
• Intraprotein Contact Analysis: Counts stabilizing and destabilizing intraprotein contacts to assess structural transitions and regional contributions to stability.
• PDB File Compatibility: Operates directly on Protein Data Bank (PDB) files for structure-based analysis.
• Dual-Sided Analysis: Identifies fragments that can transition into disordered states (the "dark" side) and nonstable regions of alpha helices and beta strands that can transition to random coils or revert (H↔C, E↔C) (the "light" side).
• Residue Enrichment Insights: Reports residue enrichment patterns associated with transitions, including enrichment of Ala, Met, Asp, Lys in regions turning disordered and enrichment of hydrophilic residues plus Cys, Pro, Gly in regions transitioning to random coils.
• Stability Impact Assessment: Includes an option to evaluate the impact of secondary-structure transitions on the stability of specific protein regions.

Scientific Applications:

• IDP Structural Analysis: Provides detailed insights into structural instability and transition dynamics of intrinsically disordered proteins relevant to cellular regulation.
• Functional and Mutational Impact Prediction: Aids in elucidating functional mechanisms of IDPs and in predicting how mutations or environmental changes might affect protein stability and function.

Methodology:

Implements propensity scales derived from structural data of disordered middle regions (excluding termini), counts stabilizing and destabilizing intraprotein contacts, analyzes PDB files to identify H↔C and E↔C transitions and residue enrichment patterns, and assesses the impact of secondary-structure transitions on regional stability.