Partial molar volumes of organic compounds in water. Part 5.—Betaines of α,ω-aminocarboxylic acids

Abstract

The partial molar volumes of a number of w-(N,N,N-trimethyl-amino)-a-carboxylic acids in water at 25°C have been measured, and related to their van der Waals volumes. The effects of progressive methylation of the nitrogen atom are examined and volume changes arising from electrostriction of the solvent or hydrophobic hydration effects are deduced. It is shown that the interaction of the trimethylalkylammonium group in the betaines with the solvent is identical to that of the alkylammonium group with the solvent in the corresponding aminoacids.

Partial molar volumes of phenalkylamines and their physiologically active derivatives in water

“…Results indicate that except for epinephrine, ephedrine, and amphetamine, AvoI values are almost constant for the amines studied in this work. Methylation on a-carbon atom or the nitrogen centre reduces the volumes of proton ionization (epinephrine, ephedrine, and amphetamine), in support of our previous findings for other systems (12,17) and in agreement with the general expectation that secondary amines have lower AvoI values than primary amines.…”

“…These larger volume increments in amine hydrochlorides are caused by the effect of the charge on the orientation of water molecules around the methyl substituent, as well as its effects on reducing the electrostriction of water molecules by the charged group (15,17). The b, values for phenethylamine derivatives of Table 2 do not follow any discernible trend.…”

Effect of Pseudorepeat Rearrangement on α-Synuclein Misfolding, Vesicle Binding, and Micelle Binding

“…Relative to lysozyme ( D 0 = 11.3×10 -11 m 2 s -1 ), an unhydrated micelle radius of 22.2 Å is thus obtained. Using an SLAS density of 1.11 g/cm 3 , calculated from the experimentally determined partial molar volumes of its sarcosine, carbonyl and hydrocarbon moieties72,73 using Traube's additivity rule,73 an average micelle mass of 30.6 kDa and an aggregation number of 104 are obtained, respectively.…”

Compatible solutes: Thermodynamic properties relevant for effective protection against osmotic stress

“…Solution densities for the systems with other CSs considered in this work were taken from literature (glycerol [23], DMSO [24], glycine [25], MG [26], TMG [27], urea [28], and ectoine [12]). …”