Latent periodicity of protein sequences

This article is in the area of protein sequence investigation. It studies p rotein sequence periodicity. The notion of latent periodicity is introduced . A mathematical method for searching for latent periodicity in protein seq uences is developed. Implementation of the method developed for known cases of perfect and imperfect periodicity is demonstrated. Latent periodicity o f many protein sequences from the SWISS-PROT data bank is revealed by the m ethod and examples of latent periodicity of amino acid sequences are demons trated for: the translation initiation factor EIF-2B (epsilon subunit) of S accharomyces cerevisiae from the E2BE_YEAST sequence; the E. coli ferriente rochelin receptor from the FEPA_ECOLI sequence; the lysozyme of Bacteriopha ge SF6 from the LY_BPSF6 sequence; lipoamide dehydrogenase of Azotobacter v inelandii from the DLDH_AZOVI sequence. These protein sequences have latent periods equal to six, two, seven and 19 amino acids, respectively. We prop ose that a possible purpose of the amino acid sequence latent periodicity i s to determine certain protein structures.