Empirical equations for predicting ¹³C chemical shifts in nuclear magnetic resonance spectra of certain types of amino acids

Abstract

13C chemical shift data were obtained for amino acids related to glycine which had the following types of substituents on C-2: alkyl, branched chain alkyl, ω-amino alkyl, and ω-guanido alkyl. Such data were obtained for aqueous solutions at a pH between the pK values of the carboxyl and 2-amino groups (zwitterion form). The data were subjected to graphical and statistical analysis to obtain separate predictive equations for C-1, C-2, and other carbon atoms. Data for the change in chemical shifts on titration with acid were also obtained to aid in 13C assignments and to elucidate configuration.

Phosphorus-31, nitrogen-15, and carbon-13 and NMR of glyphosate: comparison of pH titrations to the herbicidal dead-end complex with 5-enolpyruvoylshikimate-3-phosphate synthase

“…acids (Suprenant et al, 1980;Rabenstein & Sayer, 1976;MacDonald et al, 1976;Batchelor, 1975;Batchelor et al, 1975; Horsely & Sternlicht, 1968; Horsley et al, 1970). Data for glycine and other amino acids in aqueous solutions at different pHs are reported, and most amino acids by 13C NMR have a constant deshielding of = 2.4 for the ionization of the COOH group.…”

Antimicrobial metabolites produced by an intertidal Acremonium furcatum

“…A comparison of the remaining high-field proton and carbon signals with the literature data for amino acids (MacDonald et al, 1976) showed that compound 1 contained a substructure similar to the amino acid isoleucine, but in a reduced way, isoleucinol, as 2D experiments revealed. The connectivities observed in the HMBC experiment are shown in Fig.…”

“…The 2D NMR spectroscopic experiments showed that all the correlations in the high field region were merely duplicated and partially overlapped. Furthermore, the available 13 C NMR spectroscopic data for amino acids (MacDonald et al, 1976) suggested that 1 and 2 were a 3:1 mixture of C-2 epimers, i.e. D-allo-IleOH:L-IleOH or L-allo-IleOH:D-IleOH, indicating that the major epimer was either D-allo or L-allo-IleOH, whereas the minor component was L-or D-IleOH.…”

Synthesis of 13C labeled β-cyano-ʟ-alanine

“…13 C-NMR of the side product was in good agreement with the data given for 2,4-diaminobutyric acid (10). 15 Due to compound 10, being the reduced derivative of 2, we suppose that compound 10 is formed by the reduction of the CN group. NMR analysis showed the ratio of the products as 2:10 = 95:5.…”

“…In this context, carbobenzoxy-ʟ-asparagine 3 , trityl-ʟ-asparagine 4 , BOC-ʟ-asparagine 5 , (o-nitrophenylsulfenyl)asparagine 6 , and 3-amino-2-oxetanone salts 7 were used as the key compounds in the syntheses of β-cyanoalanine. β-Cyanoalanine labeled with 14 C or 15 N in the cyano group was prepared using immobilized cyanoalanine synthase (EC 4.4.1.9). 8 14 C-and 15 C-labeled β-cyano-ʟ-alanine were prepared by cyanidation of labeled cysteine catalyzed by cyanoalanine synthase.…”