Solid-state NMR spin-echo investigation of the metalloproteins parvalbumin, concanavalin A, and pea and lentil lectins, substituted with cadmium-113

Paul S. Marchetti, Lokesh Bhattacharyya, Paul D. Ellis, C. Fred Brewer

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Abstract

Solid-state 113Cd NMR spectroscopy of static powder samples of 113Cd-substituted metalloproteins, parvalbumin, concanavalin A, and pea and lentil lectins, was carried out. Cross polarization followed by application of a train of uniformly spaced π pulses was employed to investigate the origin of residual cadmium NMR linewidths observed previously in these proteins. Fourier transformation of the resulting spin-echo train yielded spectra consisting of uniformly spaced lines having linewidths of the order of 1-2 ppm. The observed linewidths were not influenced by temperature as low as -50°C or by extent of protein hydration. Since the echo-train pulse sequence is able to eliminate inhomogeneous but not homogeneous contributions to the linewidths, there is a predominant inhomogeneous contribution to cadmium linewidths in the protein CP/MAS spectra. However, significant changes in spectral intensities were observed with change in temperature and extent of protein hydration. These intensity changes are attributed for parvalbumin and concanavalin A to changes in cross-polarization efficiency with temperature and hydration. For pea and lentil lectins, this effect is attributed to the elimination of static disorder at the pea and lentil S2 metal-ion sites due to sugar binding.

Original languageEnglish (US)
Pages (from-to)417-426
Number of pages10
JournalJournal of Magnetic Resonance (1969)
Volume80
Issue number3
DOIs
Publication statusPublished - Dec 1988

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