TY - JOUR

T1 - Solid-state 17 O NMR of amino acids

AU - Pike, K.J.

AU - Lemaitre, V.

AU - Kukol, A.

AU - Anupõld, T.

AU - Samoson, A.

AU - Howes, A.P.

AU - Watts, A.

AU - Smith, M.E.

AU - Dupree, R.

PY - 2004

Y1 - 2004

N2 - 17 O solid-state NMR from 14 amino acids is reported here, greatly increasing the number investigated. In most cases well-separated resonances from carbonyl and hydroxyl oxygens with distinct second-order quadrupolar line shapes are observed using a 600 MHz spectrometer with fast magic angle spinning (MAS). This is in contrast to the motionally averaged resonances usually seen from amino acids in solution. For amino acids double-angle rotation (DOR) produces a decrease in the line width by more than a factor of 40, providing very high resolution, ∼ 1 ppm, spectra. The oxygen lines in alanine and the carbonyl oxygens in L-glutamic acid hydrochloride are assigned using 1H-decoupled DOR. The NMR interaction parameters for amino acids show a wide variation of XQ, from 6.4 to 8.6 MHz, η from 0.0 to 0.9, and δiso from 83 to 353 ppm. The high quality of the MAS NMR line shapes obtained at 14.1 T means that even small changes in parameters can be very accurately deduced, offering the possibility of 17O NMR as a sensitive probe of structural changes in these and related compounds. The D- and L-forms of glutamic acid hydrochloride are shown to have the same NMR parameters to within error, which are very different from those reported in the literature for the D,L-form. A strong correlation (∼-1200 ppm/Å) is found between δiso and the C-O bond length of the carbonyl oxygens. On the basis of these data, enriching specific amino acids in more complex polypeptides and proteins could provide site-selective information about the bonding and functionality of different sites in biomolecules. An estimate is made of the possible detection limit for such species.

AB - 17 O solid-state NMR from 14 amino acids is reported here, greatly increasing the number investigated. In most cases well-separated resonances from carbonyl and hydroxyl oxygens with distinct second-order quadrupolar line shapes are observed using a 600 MHz spectrometer with fast magic angle spinning (MAS). This is in contrast to the motionally averaged resonances usually seen from amino acids in solution. For amino acids double-angle rotation (DOR) produces a decrease in the line width by more than a factor of 40, providing very high resolution, ∼ 1 ppm, spectra. The oxygen lines in alanine and the carbonyl oxygens in L-glutamic acid hydrochloride are assigned using 1H-decoupled DOR. The NMR interaction parameters for amino acids show a wide variation of XQ, from 6.4 to 8.6 MHz, η from 0.0 to 0.9, and δiso from 83 to 353 ppm. The high quality of the MAS NMR line shapes obtained at 14.1 T means that even small changes in parameters can be very accurately deduced, offering the possibility of 17O NMR as a sensitive probe of structural changes in these and related compounds. The D- and L-forms of glutamic acid hydrochloride are shown to have the same NMR parameters to within error, which are very different from those reported in the literature for the D,L-form. A strong correlation (∼-1200 ppm/Å) is found between δiso and the C-O bond length of the carbonyl oxygens. On the basis of these data, enriching specific amino acids in more complex polypeptides and proteins could provide site-selective information about the bonding and functionality of different sites in biomolecules. An estimate is made of the possible detection limit for such species.

KW - Carboxylic acids

KW - Chemical bonds

KW - Correlation methods

KW - Hydrochloric acid

KW - Nuclear magnetic resonance

KW - Resonance

KW - Solutions

KW - Double-angle rotation (DOR)

KW - Dynamic angle spinning (DAS)

KW - Magic angle spinning (MAS)

KW - Amino acids

U2 - 10.1021/jp049958x

DO - 10.1021/jp049958x

M3 - Journal article

VL - 108

SP - 9256

EP - 9263

JO - Journal of Physical Chemistry B

JF - Journal of Physical Chemistry B

SN - 1520-6106

IS - 26

ER -