Wyniki wyszukiwania - BazTech

Ograniczanie wyników

Znaleziono wyników: 2

Liczba wyników na stronie

Wyniki wyszukiwania

Wyszukiwano:
w słowach kluczowych: coordination mode

Sortuj według:

Ogranicz wyniki do:

Peptydy jako potencjalne ligandy wiążące jony metali przejściowych

Krupa K., Lesiów M. K., Kowalik-Jankowska T.

Wiadomości Chemiczne

2018

[Z] 72, 7-8

597--608

Peptides are crucial ligands for transition metal ions and form complexes with them, that can have important biological activity. Many factors impact on the creation of complexes such as: protection of amine group from N-terminal or carboxylate group from C-terminals of the protein, the presence of noncoordinating and coordinating side chains in the peptide sequence, the number of histidyl residues and their location in the peptide chain. In complexes the metal ion can be bound bound by various donor atoms from amino acids residues (e.g. nitrogen, oxygen or sulphur). In general, the protection of N- or C-terminal groups influences the less stable formation of complexes. Stable complexes are created, if the free amine group from the N-terminal is involved in the coordination process. Peptides with noncoordinating side chains include alanine or glycine. Glycine complexes are more stable than these with alanine. Histidyl residue is the most effective amino acid residue in binding metal ions. The amine group of the lysyl residue, thiol from cysteine or carboxylate from aspartyl or glutamyl residues are also functional groups that coordinate metal ions. The coordination process is initiated by a group that anchors metal ion. A free amine group from N-terminus or imidazole nitrogen are the best examples of anchor groups. The metal ions can also be bound through amide nitrogens, after their forced deprotonation by the anchor group and formation of chelate rings. Peptides containing two or more histidyl residues exhibit high structural diversity in the complexes formation. In addition, these peptides can also form macrochelates and polynuclear complexes. The location of amino acid residues in the peptide chain (especially histydyl residue) also results in the thermodynamically stable formation of complexes.

Reactions of Complexation of Co(II), Ni(II), Cu(II), Cd(II) and Hg(II) Ions with Adenosine 5'-Diphosphate

Łomozik L., Gąsowska A., Bregier-Jarzębowska R.

Polish Journal of Chemistry

2004

Vol.78 /nr 11-12

2023-2035

The reaction of complexation has been studied in the systems of the ions: Co(II), Ni(II), Cu(II), Cd(II) and Hg(II) with adenosine 5_-diphosphate. The composition and stability constants of the complexes formed have been determined by the potentiometric method. The presence of the species type: MHL, MLx, and MLOH has been confirmed and their mode of coordination has been identified on the basis of the spectral data. In the acidic solution, the coordination dichotomy N(1)/N(7) has been found in all systems studied. At pH above 7, the dichotomy does not occur in the systems with Cu(II), while in the systems with Hg(II) only phosphate groups are involved in metallation. In the synthesized solid complexes of Cd(II) with AMPor ADP, the metal ion is bound by the donor nitrogen atom N(1), and in the complexes with ATP by the nitrogen atom N(7) of the nucleotide. Moreover, in the species with adenosine di- and triphosphate, the oxygen atoms of the phosphate groups are engaged in the complexation, while in the species Cd(AMP), similarly as in the liquid phase, the phosphate group is not involved in metallation.