Comparative Physiochemical Analysis Of Phenylalanine, Tryp-tophan & Methionine in Aqueous Solutions Of Nitrates In terms of Linear, Exponential, Second Order Polynomial and Third Order polynomial Using Volumetric Approach

Abstract

Volumetric properties of phenylalanine (C₉H₁₁NO₂), tryptophan(C₁₁H₁₂N₂O₂) & methionine (C₅H₁₁NO₂S) in aqueous solutions of Nitrates at T =298.15K, in terms of Linear, Exponential, Second Order Polynomial and Third Order polynomial has been calculated using volumetric approach. The densities, Partial molar volumes and transfer partial molar volumes have been calculated on the basis of density measurements of   phenylalanine, tryptophan and methionine, respectively. The results have been compared using mathematical operations like exponential behavior, second and up to third order polynomials. Interesting observations were found on the basis of comparisons in between these mathematical operations. However it has been found that phenylalanine and tryptophan in water has positive slope linearly so considered has structure makers in water while methionine has negative slope in water, considered as structure breakers. However with the intermission of nitrates, the value of slope becomes reverse except at 1.0 mol?kg^-1. This suggests that solution thermodynamics has been played major role in protein/amino acids stability.

Case Description: Phenylalanine, Tryptophan, Methionine amino acids have taken and attempt has been made to correlate the molar volumes calculated in terms of densities change with the change in the concentration of cosolute (sodium nitrate) and then identifies the curves or behvaior in terms of various mathematical operations so as to reach conclusion about strucutre making/ breaking behavior of these amino acids.

Discussion and Evaluation:  Phenylalanine and tryptophan in water has positive slope (linearly) so considered has structure makers in water while methionine has negative slope in water, considered as structure breakers. However with the addition of nitrates, the value of slope becomes reverse except at 1.0 mol?kg^-1. While on the basis of third order polynomial which seems to be more accurate as they have higher R² (Regression) values near to 1.0; which proves the fact that trivalent interactions (3^rd order) are more important as compared to divalent and monovalent.

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nclusions: Amino acids are very much affected by the addition of cosolute like in our case (sodium nitrate) and therefore there behavior as well as properties changes very significantly with the change in the concentration effect of colsolute. Thus, concentration effect is an important parameter for slating in/ salting out of amino acids.