Critical evaluation of the stability constants of metal complexes of amino acids with polar side chains (Technical Report)

Abstract

Abstract

The compounds of leucine with copper (II) cations in aqueous solutions

“…где Кд -константа диссоциации лейцина равная 2,4 [12]. С помощью математических преобразо-ваний из формулы (5) получено квадратное уравнение вида α 2 + 2,4α -2,4 = 0 (6) С учётом того, что α не может быть отрица-тельной величиной, из двух корней квадратного уравнения был выбран корень, равный 0,9611.…”

Formation constants of copper(i) complexes with cysteine, penicillamine and glutathione: implications for copper speciation in the human eye

“…The major reasons for this are: (i) Cu(I) is readily oxidised or, as noted above, disproportionates to Cu(II) in aqueous media in the absence of suitable complexing agents; 22 (ii) both the thioamino acids and their complexes are also readily oxidised; (iii) sparingly soluble precipitates are formed over wide pH ranges (especially with cysteine and glutathione); and (iv) all of these systems show pronounced tendencies to form protonated and polynuclear complexes. 23 In spite of these difficulties the biological relevance of the Cu(I) complexes of these particular thioamino acids has motivated many attempts to characterize them. Unfortunately, however, there is little agreement about the stoichiometry of the species formed, let alone their formation constants (see, e.g., Refs.…”

“…The tendency of CSH to form protonated and polynuclear complexes with a variety of metal ions is well known. 23 Interestingly, Bagiyan et al 46 indicated that protonated complexes of Cu(CS)  formed readily during their pH-metric titrations but only reported a value for  110 (Table 5). 28 Consistent with the present findings, Harman and Sóvágó 49 have pointed out that the degree of formation and stoichiometry of M n+ PSH polynuclear complexes should be markedly different from those for M n+ CSH due to steric inhibition by the -methyl substituents in the former.…”

Thermodynamic and spectroscopic study for the interaction of dimethyltin(IV) with L–cysteine in aqueous solution

“…4 interaction of the organotin moieties with several biologically relevant compounds such as carbohydrates, amino acids, peptides, nucleic acids and DNA has been carried out mostly in the last decade [8][9][10][11][12][13][14][15][16][17][18][19][20][21]. From some of these cited studies, the interaction of dimethyltin (IV) and trialkyltin(IV) (with R = methylic, ethylic, and butylic groups) in aqueous solution, at physiological pH, with thiol groups of model molecules, as well as feline and rat haemoglobin, have been investigated by 119 Sn Mössbauer spectroscopy.…”

“…In particular, no calorimetric study has been performed. The , Hg 2+ and others, but there are no enthalpic data on tin or alkyltin cations [21].…”