¹H and ³¹P NMR studies of rotational isomerism in phosphorus analogues of aspartic acid, 3‐amino‐3‐phosphonatopropionic and 3‐amino‐3‐(methylphosphinato) propionic acids

Abstract

By the use of the 'H-lH and 'H-"P coupling constants in two analogues of aspartic acid i.e. 3-amino-3-phosphonatopropionic and 3-amino-3-(methylphosphinato) propionic acids, it was shown that the six parameter formulation for the evaluation of mole fractions of three staggered ethanic rotamers is not necessarily better than the two parameter formulation in this system. The results allowed the recommendation of the following values for the two vicinal proton parameters i.e. J(HH)g=2.3, J(HH) t = 13.9 and for the two vicinal proton-phosphorus parameters i.e. J(HP)g= 4.2, J(HP)t= 33.0 Hz.

Structure of 2-amino-3-phosphonopropionic acid, C3H8NO5P

“…The conformation of the molecule is stabilized by the formation of an intramolecular hydrogen bond between the amino group and the O atom of the phosphonic group. The intramolecular distance between H(5) and O(1) is 2.04 (4)~ and between N and O(1) 2-805 (4) rotational isomerism in this molecule is similar to that found for a-PAsp (Siatecki & Koztowski, 1980, 1981. The most stable rotamer is the one with carboxyl and phosphonic groups trans relative to each other (rotamer 2 in Fig.…”

“…The NMR spectra of the aqueous (D20) solutions of fl-PAsp and its methylphosphinic analogue (fl-PCH3Asp) were recorded on a 100 MHz JEOL PS 100 spectrometer at 298 K. The proton spectra were analysed as ABCX (X-alp) systems using LAOCN3 (Siatecki & Koz|owski, 1980, 1981.…”

Determination of rotamer populations and related parameters from NMR coupling constants: a critical review

“…In the phosphonic acid analogue of aspartic acid, Siatecki and Kozłowski estimated trans and gauche phosphorus-proton coupling constants from the rotamer populations determined from 3 J HH . The values found were and [83,84]. These limiting values were also recently used in the analysis of phosphonic acid analogues of aspartic acid and asparagine [94,95].…”

Three-Dimensional Structure of Cyclohexapeptides Containing a Phosphinic Bond in Aqueous Solution: A Template for Zinc Metalloprotease Inhibitors. A NMR And Restrained Molecular Dynamics Study

“…Such different values are not expected for a rotamer I, as this conformation places the two Hp rotons of residue Phe3 in the gauche orientation relative to the phosphorus atom. Nevertheless, it should be pointed out that some studies of phosphorus compounds have reported vicinal proton-phosphorus coupling constants of 4.2 Hz, corresponding to a gauche orientation of the proton relative to the phosphorus, and 33 Hz, for the trans orientation.33 This set of 3s/g(H-P) and 3e7t(H-P) values, which is not necessarily the more appropriate set for a phenylalanylphosphinyl residue, due to the marked difference between 3Jg and 3Jt, indicates that a small percentage of the rot. II will be sufficient to produce the observation of different 3J(H/?-P) coupling constants, as those reported for the Phe3 of this peptide.…”