th - 1988 - 51st ENC Conference
th - 1988 - 51st ENC Conference
th - 1988 - 51st ENC Conference
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F 98<br />
I CHEMICAL EXCHANGE OF HETERONUCLEAR LONGITUDINAL<br />
TWO-SPIN ORDER (IzSz): A DYNAMIC PROBE OF CONFORMATIONAL<br />
ISOMERIZATION IN PROTEINS Gaetano T. Montelione* and Gerhard<br />
Wagner, Biophysics Research Division, University of Michigan, Ann<br />
Arbor, MI 48109.<br />
Chemical exchange spectroscopy can provide information about rates of<br />
conformational isomerization for systems which are in slow dynamic<br />
equilibrium. In such measurements it is often necessary to distinguish<br />
magnetization transfer <strong>th</strong>rough chemical exchange from cross-relaxation due<br />
to dipolar coupling. This distinction can be made by developing longitudinal<br />
two-spin order (i.e. zz-order) via scaler coupling wi<strong>th</strong>in one conformer and<br />
transferring it by chemical exchange to <strong>th</strong>e o<strong>th</strong>er conformer(s) which are in<br />
slow-exchange on <strong>th</strong>e chemical shift timescale 1,2. We have employed <strong>th</strong>is<br />
concept in developing 2D-NMR pulse sequences which characterize <strong>th</strong>e chemical<br />
exchange of natural abundance heteronuclear two-spin order (IzSz). These<br />
"heteronuclear zz-exchange" experiments provide information about bo<strong>th</strong> rate<br />
and equilibrium constants for slow dynamic processes in polypeptides and<br />
proteins. The me<strong>th</strong>ods are applicable to studies of slow peptide-bond<br />
isomerization, aromatic ring rotations, and <strong>th</strong>e folding / unfolding dynamic<br />
equilibria of small proteins.<br />
1. Bodenhausen et al. (1984) J. Mag. Reson. 59: 542.<br />
2. Wagner et al. (1985) J. Am Chem. Soc. 107: 6440.<br />
I -- 99 I TEACHING MRI USING COMPUTER ANIMATION, Joseph P. Hornak,<br />
Rochester Institute of Technology, l~ochester, NY 14623<br />
Involving undergraduate students in magnetic resonance research requires a carefully<br />
planned education program in <strong>th</strong>e principles of magnetic resonance. Such a program often<br />
requires <strong>th</strong>e student to learn <strong>th</strong>e principles independently as <strong>th</strong>ere are usually no appropriate<br />
courses at <strong>th</strong>e sophomore and jumor level. Several dynamic aspects of NMR spectroscopy and<br />
imaging are difficult for <strong>th</strong>e student to understand when textbooks wi<strong>th</strong> static diagrams are used,<br />
and consequently, significant amounts of time are spent by <strong>th</strong>e research advisor explaining <strong>th</strong>ese<br />
concepts which could better be taught by o<strong>th</strong>er means. One solution to <strong>th</strong>is problem is to utilize<br />
computer animation for teaching magnetic resonance. A computer based teaching package of <strong>th</strong>e<br />
basics of NMB. imaging is described which presents several of <strong>th</strong>e dynamic processes of magnetic<br />
resonance wi<strong>th</strong> computer animation and text which simultaneously appear on a computer screen.<br />
Some of <strong>th</strong>e topics taught by <strong>th</strong>is package are <strong>th</strong>e rotating frame, pulse sequences, <strong>th</strong>e behavior of<br />
magr/etization during a two dimensional imaging sequence, and two dimensional Fourier<br />
transforms.<br />
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