Natural isotope deconvolution

Applications to Biological Samples. - Methods of distance measurements were compared for four doubly spin-labelled derivatives of human carbonic anhydrase.53 The distances between the spin labels were obtained from continuous wave spectra by analysis of the relative intensity of the half-field transition, Fourier deconvolution of the line-shape broadening, and computer simulation of line-shape changes. For variants with interspin distances greater than 18 A, the DEER method also was used. For each variant, at least two methods were applicable and reasonable agreement between distances obtained by different methods was obtained. The useful distance ranges for the techniques employed at X-band with natural isotope abundance spin labels were estimated to be half-field transition (5-10 A), line-shape simulation (up to 15 A), Fourier deconvolution (8 - 20 A), and four-pulse DEER (> 18 A).53... 

Thus, the D/H exchange rate must be much faster than the refolding rate. The relative abundance of the two envelopes thus provides a direct measure of the relative concentrations of folded and unfolded protein. (Although the two distributions do not overlap in this example, deconvolution of the natural-abundance isotope distribution... 

Zhang, Z.,Gutm, S., Marshall, A.G. (1997) Enhancement of the effective resolution of mass spectra of high-mass biomolecules by maximirm entropy-based deconvolution to eliminate the isotopic natural abundtmce distribution. J Am Soc Mass Spectrom, 8 (6), 659-670. 

---