Protein Quadratic Indices of the Ã¢Â€ÂœMacromolecular PseudographÃ¢Â€Â™s ÃŽÂ±-Carbon Atom Adjacency MatrixÃ¢Â€Â. 1. Prediction of Arc Repressor Alanine-mutantÃ¢Â€Â™s StabilityAuthor(s): Yovani Marrero Ponce | Ricardo Medina Marrero | Eduardo A. Castro | Ronal Ramos de Armas | Humberto GonzÃƒÂ¡lez DÃƒÂaz | Vicente Romero Zaldivar | Francisco Torrens
Journal: Molecules ISSN 1420-3049
Volume: 9; Issue: 12; Start page: 1124; Date: 2004;
Keywords: Protein Stability | Arc Repressor | Alanine-Substitution Mutant | TOMOCOMD Software | Protein Quadratic Indices | QSPR.
This report describes a new set of macromolecular descriptors of relevance toprotein QSAR/QSPR studies, proteinÃ¢Â€Â™s quadratic indices. These descriptors are calculatedfrom the macromolecular pseudographÃ¢Â€Â™s ÃŽÂ±-carbon atom adjacency matrix. A study of theprotein stability effects for a complete set of alanine substitutions in Arc repressorillustrates this approach. Quantitative Structure-Stability Relationship (QSSR) modelsallow discriminating between near wild-type stability and reduced-stability A-mutants. Alinear discriminant function gives rise to excellent discrimination between 85.4% (35/41)and 91.67% (11/12) of near wild-type stability/reduced stability mutants in training andtest series, respectively. The modelÃ¢Â€Â™s overall predictability oscillates from 80.49 until82.93, when n varies from 2 to 10 in leave-n-out cross validation procedures. This valuestabilizes around 80.49% when n was