Structural features of single amino acid repeats in proteins

Single amino acid repeats are found in different kinds of proteins. Some of these repeats are pathogenic. It is striking that some amino acids are abl e to form such repeats, but other amino acids are not. We suggest an explan ation for this fact based on the different tendency of each amino acid to f orm aggregates. Aggregation may be due to the formation of incipient lamell ar crystals as they have been described in poly-alpha-amino acids and in mo st synthetic polymers. (C) 1999 Federation of European Biochemical Societie s.