Thermodynamic stereoselectivity assisted by weak interactions in metal complexes. Copper(II) ternary complexes of cyclo-L-histidyl-L-histidine and L- or D-amino acids in aqueous solution

Author(s):  
Giuseppe Arena ◽  
Raffaele P. Bonomo ◽  
Luigi Casella ◽  
Michele Gullotti ◽  
Giuseppe Impellizzeri ◽  
...  
2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Naciye Türkel

Nickel is one of the essential trace elements found in biological systems. It is mostly found in nickel-based enzymes as an essential cofactor. It forms coordination complexes with amino acids within enzymes. Nickel is also present in nucleic acids, though its function in DNA or RNA is still not clearly understood. In this study, complex formation tendencies of Ni(II) with adenine and certain L-amino acids such as aspartic acid, glutamic acid, asparagine, leucine, phenylalanine, and tryptophan were investigated in an aqueous medium. Potentiometric equilibrium measurements showed that both binary and ternary complexes of Ni(II) form with adenine and the above-mentioned L-amino acids. Ternary complexes of Ni(II)-adenine-L-amino acids are formed by stepwise mechanisms. Relative stabilities of the ternary complexes are compared with those of the corresponding binary complexes in terms ofΔlog10⁡K,log10⁡X, and % RS values. It was shown that the most stable ternary complex is Ni(II):Ade:L-Asn while the weakest one is Ni(II):Ade:L-Phe in aqueous solution used in this research. In addition, results of this research clearly show that various binary and ternary type Ni(II) complexes are formed in different concentrations as a function of pH in aqueous solution.


Polyhedron ◽  
2001 ◽  
Vol 20 (1-2) ◽  
pp. 103-109 ◽  
Author(s):  
Francesco Dallavalle ◽  
Giuseppina Folesani ◽  
Antonio Sabatini ◽  
Matteo Tegoni ◽  
Alberto Vacca

1998 ◽  
Vol 44 (3-4) ◽  
pp. 225-235 ◽  
Author(s):  
Francesco Dallavalle ◽  
Giuseppina Folesani ◽  
Enrico Leporati ◽  
Renato Borromei

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