SAPS (EBI)

SAPS (EBI) performs statistical analyses of protein primary sequences to quantify compositional biases, local residue clustering, long runs, periodic patterns, homooligopeptide distributions and unusual inter-residue spacings to support structural and functional interpretation.

Key Features:

• Global compositional bias calculation: Computes overall amino acid composition and identifies deviations from expected residue frequencies.
• Local residue distribution metrics: Quantifies local distributions and clustering of residue types, including charged and hydrophobic residues.
• Run detection: Identifies and characterizes long runs of charged or uncharged residues in primary sequences.
• Periodicity and motif analysis: Detects periodic patterns and locally periodic motifs within protein sequences.
• Homooligopeptide counting: Counts and maps the distribution of homooligopeptides and repetitive oligomer occurrences.
• Inter-residue spacing analysis: Detects unusual or anomalous spacings between specific residue types.
• Statistical metric reporting: Produces a range of statistical metrics that describe residue content and arrangement.

Scientific Applications:

• Protein structure analysis: Use compositional biases and local clustering metrics to infer structural attributes of proteins.
• Functional region identification: Use periodic patterns, motifs and unusual spacings to highlight potential functional regions.
• Comparative sequence analysis: Compare different protein sequences to identify unique or conserved features across species or protein families.

Methodology:

SAPS applies statistical computations to input protein primary sequences to calculate metrics describing residue content, clustering, runs, periodicity, homooligopeptide frequencies and inter-residue spacings.