Densities, Apparent Molar Volumes, and Apparent Molar Heat Capacities of l-Arginine, l-Proline and d,l-Methionine in Water at 288.15, 298.15, 313.15, and 328.15 K

Abstract

Relative densities, (ρ − ρ°1), and heat capacity ratios, cp ρ/cp °1ρ°1 − 1, for l-arginine, l-proline, and d,l-methionine in water have been measured at 288.15, 298.15, 313.15 and 328.15 K. These data have been used to calculate apparent molar volumes and apparent molar heat capacities. Calculated standard state volumes and heat capacities have been compared to available literature data. Standard state expansibilities have been calculated from the temperature dependences of standard state volume data.

Intermolecular/interionic interactions in l-isoleucine-, l-proline-, and l-glutamine-aqueous electrolyte systems

“…Thermodynamic studies of (amino acid/peptide + water) [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] and (amino acid/peptide + salt + water) systems [17][18][19][20][21][22][23][24][25][26][27][28][29] are useful to understand several biochemical processes such as protein hydration, denaturation, aggregation, etc. Nandi and Robinson [30] studied the salting in/salting out effects of several salts on biological macromolecules and inferred that salts interact directly with the peptide group.…”

Apparent and partial molar heat capacities and volumes of the amino acids l -lysine monohydrochloride andl -arginine monohydrochloride in aqueous solution at temperatures from T= 288.15 K to T= 328.15 K

“…Values for A v were taken from the compilation by Archer and Wang. (24) The V ∞ m,φ and B v results, together with their standard errors obtained from weighted least-squares analyses of the apparent molar volume data using equation (2), are given in table 3. Table 4 gives a comparison of the V ∞ m,φ and B v results obtained in this study with those reported in the literature.…”

“…HCl appear to be consistent with those of other amino acid systems. (2,13) The apparent molar heat capacities of the amino acid hydrochlorides, C p,m,φ , were obtained from measured relative massic heat capacities using the equation:…”

“…Solution densities were measured using an Anton Paar digital density meter (model DMA 60/602) or a Sodev O2D vibrating tube densimeter as outlined previously. (1,2,19,20) For the DMA 60/602, the reproducibility of an individual density measurement was to better than 3 · 10 −3 kg · m −3 , whilst the uncertainty in a density measurement using the Sodev instrument is 5 · 10 −3 kg · m −3 . Heat capacity measurements were carried out using a Picker differential flow microcalorimeter.…”

“…There has been considerable interest in recent years in the determination of several thermodynamic properties for amino acids, (1)(2)(3)(4)(5) small peptides, (6)(7)(8)(9)(10)(11) and other structurally related solutes (12,13) in aqueous solution. One reason for the interest in these systems is because the solute molecules, which incorporate some of the structural features found in proteins, can be used to model specific features of the complex protein molecules a To whom correspondence should be addressed (E-mail: hakin@uleth.ca).…”