Volumetric and Viscosity Properties of α-Amino Acids and Their Groups in Aqueous Sodium Caproate Solutions

Abstract

Densities and viscosities have been measured for solutions of DL-R-valine or DL-R-leucine in aqueous sodium caproate solutions at 298.15 K and 308.15 K. On the basis of these data, the apparent molar volumes (V m,2 ), standard partial molar volumes (V°m ,2 ), standard volumes of transfer (∆ t V°), hydration number (n H ), and viscosity B-coefficients of DL-R-valine and DL-R-leucine have been determined. Combined with the corresponding data of glycine, DL-R-alanine, and DL-R-amino-n-butyric acid reported recently, it has been shown that the standard partial molar volumes and the viscosity B-coefficients of the amino acids vary linearly with increasing number of carbon atoms in the alkyl chain of the amino acids. These properties have been split into contributions from the zwitterionic end group (NH 3 + , COO -) and CH 2 groups of the amino acids by using linear relations. The volumetric data suggest that sodium caproate interacts strongly with the zwitterionic end group of the amino acids, and the electrolyte has a strong dehydration effect on the amino acids. Viscosity data have been discussed on the basis of structure effects of the amino acids and their groups in the solutions.

Effect of sodium caproate on the volumetric and conductometric properties of glycyl-l-glutamine and l-alanyl-l-glutamine in aqueous solution at 298.15K

“…This indicates that with increasing hydrocarbon chain length of the carboxylate ion, the dehydration effect increases. The same observation has also obtained for ␣-amino acids [14] and glycyl dipeptides [18] in aqueous sodium carboxylate solutions.…”

“…Sodium carboxylate containing the large-size anions is known to influence the dissociation of proteins in solutions [4]. The effect of some alkali metal and alkaline earth metal carboxylates on the physico-chemical properties of amino acids has been studied by some workers [5][6][7][8][9] and our group [10][11][12][13][14] in order to understand the fine details of the interactions of the protein with carboxylate salts. In recent years, we have carried out the investigations on thermodynamic properties of some small peptides in aqueous sodium carboxylate solutions [15][16][17][18] because small peptides contain more complex structure and more components of proteins than amino acids.…”

Viscosities of l-Histidine/l-Glutamic Acid/l-Tryptophan/Glycylglycine + 2 M Aqueous KCl/KNO3 Solutions at T = (298.15 to 323.15) K

“…Viscosity studies of some amino acids and peptides have been reported for alkali chlorides [3], KSCN [4,5], NH 4 Cl [6], urea [7], sodium butyrate [8], sodium acetate [9,10], tetra-n-alkylammonium bromide [11,12], caffeine [13], sodium caproate [14], MgCl 2 [15], NaC 6 [16], CaCl 2 [17], magnesium acetate [18], tetramethyl ammonium iodide [19], Cu II nitrate and Ni II chloride [20], surfactant [21], methanol [22], d-glucose [23], potassium citrate salt solutions [24], and KCl and KNO 3 solutions [25]. Kumar et al [11,26,27] have reported the effect of NaBr, KCl, KBr, MgCl 2 , and Na 2 SO 4 on viscosity values of some amino acids and glycylglycine.…”

Physicochemical investigation on interactions of some amino acids with aqueous tetra-butyl ammonium bromide solution at 298.15 K

“…However, there are few measurements on the interactions between amino acids and organic salts [8][9][10][11][12][13][14].…”