} \) is proportional to a PRN1371 order certain characteristic b that depends on the catalyst type $$ W_i^+ \left/ W_i+1^-=k_ib \right. $$ (7) Substitution of equation (7) into equation (6) readily gives $$ C_n=K_nb^n-1 C_1 $$ (8)whereas, dependence of the complexes concentration

C n on the catalyst is described by the b n−1 and \( K_n=\prod\limits_i=1^n-1 k_i \) can be considered as being catalyst-independent. The theoretical model above can be used Selleckchem GSK126 to obtain dependence of the L-Glu peptides concentration on the peptide length in presence of ions, if we consider the monomer is L-Glu and the catalyst B is K+ or Na+. In case of reaction (2), the dependence might be explained with different ion adsorption probabilities Seliciclib research buy onto the surface of the amino acid. For the reaction (3), the equilibrium constant \( W_i^+ \left/ W_i+1^- \right. \) should be proportional

to the diffusion coefficient \( D_K^+ \) or \( D_Na^+ \) of the corresponding ion in water. The diffusion limit gives the equation (9) for the ratio of peptide concentrations in the presence of K+ or Na+ in water solutions $$ \frac\left[ Peptide_K^+ \right]\left[ Peptide_Na^+ \right]=\left( \fracD_K^+D_Na^+ \right)^length-1 $$ (9)whereas, \( \left[ Peptide_K^+ \right] \) and \( \left[ Peptide_Na^+ \right] \) are concentrations of

the peptides, \( D_K^+ \) and \( D_Na^+ \) are diffusion coefficients of the ions in water and length is the number of L-Glu residues Fluorometholone Acetate in the peptide. Thus, the equation (9) above, with the diffusion coefficients of K+ (DK + = 1.957 × 10−5 cm2/s) and Na+ (DNa + = 1.334 × 10−5 cm2/s) in water solutions (Lide and David, 1998), clearly corresponds to the K+/Na+ ratio of the salt-mediated formation of L-Glu peptides (Fig. 2), which was calculated as the peak area of each oligomer on the chromatogram divided by the peak area of the dipeptide in the same reaction (Table 1). Fig. 2 Experimental and theoretical evidence of the K+- versus Na+-mediated formation of peptides The experimental data for the K+/Na+ ratio of L-Glu peptides was calculated from Fig. 1 as the peak area of each oligomer on the chromatogram divided by the peak area of the dipeptide in the same reaction Discussion Our experimental results demonstrate that K+ has a 3-fold to 10-fold greater catalytic effect than the same concentration of Na+ on the reaction peak of 5-mer to 8-mer L-Glu condensation in aqueous solutions. Computations and blackbody infrared radioactive dissociations have shown that Na+ is coordinated to the nitrogen and carbonyl oxygen atoms (NO coordination) of amino acids, whereas K+ is coordinated to both oxygen atoms (OO coordination), with lower binding energy (Jockusch et al. 2001).