th  - 1988 - 51st ENC Conference

96
AN EVALUATION OF NEW PROCESSING PROTOCOLS FOR IN-VIVO NMR
A.R. Mazzeo and G.C. Levy
NIH Research Resource for Multi-Nuclei NMR and Data
Processing, Syracuse University, Syracuse, NY 13244-1200.
In-vivo NMR spectroscopy is often characterized by relatively
broad resonances of low signal-to-noise superimposed on a
curved baseline formed by broad but, in some cases, real
resonances. A variety of processing techniques have been
used in the past to obtain "quantitative" information from
these difficult spectra, with varied success. Here, several
different processing protocols, using software tools
developed in this laboratory for spectral optimization, are
used and evaluated for quantification of test spectra. Both
synthetic and experimental data sets were processed using
conventional techniques (convolution difference) and with new
protocols involving Maximum Entropy Fourier Spectral
Deconvolution (MEFSD) and Linear Prediction (LP). In some
cases, baselines were corrected using an "intelligent"
baseline conditioning routine. Results show the advantages
and limitations of the various techniques.
We would like to acknowledge NIH Grant RR-01317 for support.
97 [2DNMR DETERMINATION OF '3C SPIN-LATTICE
RELAXATION TIMES IN BPTI BY INDIRECT DETECTION: N.R.Nirmala~and
Gerhard Wagner, Biophysics Research Division, University of Michigan, Ann
Arbor, MI 48109.
13C spin-lattice relaxation times provide an important clue for determining the
mobility of a protein in solution. This is of interest in itself, but it is also essential for
resolving ambiguities concerning variations in structures obtained from calculations of
three-dimensional structures using NMR data. If there exists a high degree of mobility in
only selected parts of the molecule, this will be reflected in the variation of spin-lattice
relaxation times of the corresponding 13C nuclei. Therefore, knowledge of the 13C Tl's will
aid in the study of three-dimensional structures of proteins in solution. Since typical
spectra of proteins are heavily overlapped, individual 13C Tl's can be determined only by
two-dimensional NMR. Furthermore, direct measurement of 13C spin-lattice relaxation
times is hampered by the low sensitivity of the 13C nucleus, requiring long measuring
times and high sample concentrations. Proton detection increases the sensitivity of the
experiment by a factor of ( 7H/7c)2 and is therefore preferred. In the experiment
described, a double transfer was used [1,2]. Proton magnetization was converted to 13C z-
magnetization using a DEPT-type sequence. The 13C z-magnetization was then allowed to
relax and reconverted to proton magnetization using a reverse DEPT sequence, with
decoupling of the 13C nucleus during detection. The experiment was performed with
natural abundance l aC on basic pancreatic trypsin inhibitor (BPTI). Individual Tl's of the
u-carbons were determined.
,
1. L. E. Kay, T. L. Jue, B. Bangerter and P. C. Demou, J. Mag. Res., 73, 558 (1987).
2. V. Sklenar, D. Torchia and A. Bax, J. Mag. Res., 73, 375 (1987).
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