Abstract
A lot of biological information bury in one protein, such as functions and active sites, could be available if the protein structure was known. However, it is inefficient and expensive for obtaining protein structures. Therefore, several methods, such as multiple sequence alignment (MSA), have been developed to detect important properties of proteins without structure information, but these do not always work. In this study, a simple method was designed to identify potentially critical residues for mammalian imidase and eosinophil cationic protein (ECP or RNase3) by sequence information alone. For rat imidase, 10 residues were identified by this method and were corresponded to a bacterial imidase crystal structure (1GKQ). Five residues, one lysine (Lys159), three histidines (His67, His69, His248) and one aspartate (Asp326) involved in metal coordinate in active site were identified. The other amino acid residues that might be important for the function or structure of mammalian imidase were also identified. On the other hand, for ECP, Pro3 was also identified to be critical for ECP’s toxicity, and it was also verified by the experimental result (unpublished data).