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    Apparent molal heat capacities of organic compounds in aqueous solution. Part 3.—ω-Amino acids and related compounds
    (Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1977, 73 (03), 1977) Cabani, Sergio; Conti, Giovanni; Matteoli, Enrico; Tani, Alessandro
    Values of apparent molal heat capacities ΦCp in the range 23°–55°C, were determined by adiabatic calorimetry for the following amino acids: glycine, α-alanine, α-aminoisobutanoic acid, valine, serine, threonine, sarcosine, dimethylglycine, betaine, β-alanine, β- and γ-aminobutanoic acids, δ-aminopentanoic acid and ε-aminohexanoic acid. Some hydroxy acids, sodium and ammonium salts of carboxylic acids, methyl and ethyl esters of acetic acid and glycine methylester hydrochloride have also been studied. An attempt has been made to quantify the contribution to ΦCp associated with charge separation in amphionic molecules by comparing the experimental value (ΦexpCp) for amino acids with those for similar uncharged molecules (ΦrefCp). The ΔΦ* values (ΦexpCp–ΦrefCp) thus obtained for +H3N(CH2)m COO– compounds (m= 2, 3, 4, 5) are used in order to obtain some information about the interactions between neutral or charged amino and carboxylic groups. Effects connected with the methyl additions to N+ centres in glycine or ammonium salts are considered.
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    Protolysis Kinetics of some Amino-acids Studied by the Nuclear Magnetic Resonance Spin Echo Technique
    (Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1973, 69 (2), 1973) Eley, D. D.; Fawcett, A. S.; Hey, M. J.
    Proton magnetic relaxation times have been measured as a function of pH and temperature for aqueous solutions of amino-acids in the series H3[graphic omitted]—[CH2]n—CO2 where n= 1, 2, 3, 5 and 7 and also for solutions of α-alanine, sarcosine, L-proline, picolinic acid and 2-pyrrolidone. The T1 values were independent of pH but T2 had a minimum value near to pH 6 at room temperature for most of the solutions studied. In many cases, a second minimum occurred close to pKal for the amino-acid. The data are analysed in terms of proton exchanges between amino groups and sites which are oxygen attached. Kinetic parameters are derived for some exchange reactions which have not previously been considered in connection with amino-acid solutions.