copid

copid performs protein function annotation by analyzing amino acid composition to enable alignment-free prediction of protein attributes such as subcellular localization and functional class.

Key Features:

• Modular Architecture: Three modules—search, composition, and analysis—implement distinct compositional analysis functions.
• Search Module: Searches protein sequences across six databases and ranks database proteins by Euclidean distance or compositional similarity to a query sequence.
• Composition Module: Calculates composition for individual sequences or average compositions for groups and computes specific amino acid types such as charge, polar, and hydrophobic residues.
• Analysis Module: Compares compositions between two protein classes, generates phylogenetic trees from compositional data, and produces input patterns for machine learning applications.

Scientific Applications:

• Protein function annotation: Assigns putative functions to proteins based on amino acid composition without sequence alignment.
• Subcellular localization prediction: Predicts localization attributes using compositional features of proteins.
• Protein class identification: Identifies specific classes of proteins via alignment-free compositional signatures.

Methodology:

Composition-based (alignment-free) analysis of amino acid sequences including calculation of compositions and specific residue types, computation of Euclidean distances or compositional similarities to rank database proteins, comparison of compositions between classes, generation of phylogenetic trees from compositional data, and creation of input patterns for machine learning.