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obtained from the same sardines and of fragment 33-38 of the same casein subunit, forwhich functions of enzyme inhibitor and neuropeptide were found, respectively.Due to the presence of proteolytic enzymes within cells and in extracellular medium ofa living organism, continuous degradation of peptide structures takes place. Four hundreddifferent types of peptide bonds are cleaved with different probability, and this can result ina continuously changing mosaic of numerous fragments of endogenous proteins. In alimiting case, formation of a complete fragmentome of each of them is possible.Formation of a complete fragmentome is quite probable during digestion whenexogenous proteins are supplied with food. Thus, exogenous fragments are added to thepool of endogenous fragments. Due to partial repetition of amino acid sequences theseregulators can be formed in significant amounts and noticeably influence differentprocesses of metabolism. In particular, detection of enzyme inhibitors among them showsthat the process of food protein cleavage can be inhibited by proteolysis products. Besides,fragments only just formed in the gastrointestinal tract and exhibiting antimicrobialproperties are able to take part in regulation of the microflora balance. Thus, usualconsideration of food proteins as an energy source can be appended by regulatoryproperties of their fragments because fragmentation within an organism can result ingeneration of a dynamically developing pool of exogenous regulatory oligopeptides,functions of which can change during formation of smaller fragments. The existence of theendogenous–exogenous pool of regulatory molecules makes wider the sense and content ofthe hypothesis concerning a functionally continuous totality (continuum) of naturaloligopeptides [5].Accumulation of data on structure and functions will make it possible to characterizemore completely the functional abilities of numerous protein fragments, to approachunderstanding their role in evolution and to use them in practice. Possible practicalimportance of the use of natural fragments is in dietology, therapy, as well as in sanitaryhygiene and cosmetics. Recording functional properties of nutritive protein fragments cansuggest to dieticians what food is preferable for patients, and to pharmacologists whatpeptide fragments are reasonable to use as drugs or food additives.Due to improvement of research methods, including computer analysis, our knowledgeof structural and functional properties of the global fragmentome is intensively growing.This knowledge is still not enough for complete understanding of the regulatory role offragments in living organisms. Nevertheless, already now it is possible to formulate ideasconcerning structure–functional fragmentomics of natural peptides and other substances.AcknowledgmentsThis work was supported by the Russian Academy of Sciences Presidium program “Molecular andCell Biology” and by the Chilean National Research Foundation FONDECYT (Grant No. 1080504).References1. Zamyatnin, A.A. Biophysics 53, 329-335, (2008).2. Zamyatnin, A.A. Biochemistry (Moscow) 74, 1575-1585 (2009).3. Boeckmann, B., Bairoch, A., et al. Nucleic Acid Res. 31, 365-370 (2003).4. Zamyatnin, A.A., Borchikov, A.S., et al. Nucl. Acids Res. 34, 261-266 (2006).5. Ashmarin, I.P., Obukhova, M.F. Biochemistry (Moscow) 51, 531-545 (1986).33