Osmium tetroxide and ruthenium tetroxide and their reactions with biologically important substances: Electron stains III

The Properties and Mode of Action of the Polymyxins.

Publisher Summary This chapter attempts to summarize the biological properties of poly-α-amino acids. The data already available indicate that these synthetic polypeptides may be of considerable value in the elucidation of the mode of action of known proteolytic enzymes, in the search for new proteolytic enzymes, and in the clarification of the inhibition of enzymes by macromolecules. It reviews that the close resemblance between the antibacterial and antiviral properties of basic polyamino acids with those of some natural peptides indicates that both the synthetic model compounds and the natural materials may act biologically by a similar mechanism. Also promising are the results obtained in the investigation of the immunological properties of synthetic poly-cu-amino acids and of polypeptidyl proteins, since they may contribute to the understanding of the chemical basis of the antigenicity of proteins. Finally, it is worth mentioning that water-soluble poly-a-amino acids represent one of the few types of synthetic polymers whose biological activity has been investigated in some detail. The extension of such studies to other synthetic water-soluble polymers may, perhaps, lead to the finding of new specific biological reagents. The chapter concludes that it should be stressed that the great value of synthetic poly-α-amino acids as protein models lies in their simplicity relative to the complexity of the natural proteins. Thus, many physical, chemical, and biological properties can be studied, as it were, in isolation by using such synthetic polypeptides. It should be remembered that this same simplicity imposes a limit on the usefulness of these substances, since certain properties, at least, of proteins may derive from a complexity of sequence and structure not found in the synthetic models.

Biological properties of poly-alpha-amino acids.

Enzymic transfer of sulfur from mercaptopyruvate to sulfite or sulfinates

Glyoxalase inhibitors as potential anticancer agents.

Publisher Summary This chapter discusses naturally occurring peptides, which allows several generalizations concerning their importance as distinct chemical entities. Certain physiologically active naturally occurring peptides seem to be linked to the much larger protein molecules with respect to their structure and physiological activity. The distinction is based largely on the fact that naturally occurring peptides are composed of amino acids with uncommon configurations and structures, and of linkages other than the classical peptide bond. The uncommon structures exist only rarely in proteins and this would be exactly why one can use them to differentiate the naturally occurring peptides from protein fragments. One group, containing heteromeric peptides, is characterized on the basis of a common structure and an identical amino acid composition, differing from one another by the nature of the heteromeric group. Such is the case of the penicillins. Another group also has a given identical structure, but each member of the group has a different amino acid composition. All the members of such families possess the same number of amino acids, however, are of a different nature. All the members of another group possess the same heteromeric groupings and uncommon amino acids, but they differ by the number and nature of other amino acids. The characteristic biological actions of the naturally occurring peptides are because of their uncommon structures and compositions. The biological activity is related to the structure. The existence of naturally occurring peptides show that nature utilizes amino acids to build proteins and peptides.

E. Bricas

Papers

Naturally occurring peptides.

Nouvelle synthèse de l'acide amino-2 éthanesulfinique (hypotaurine)