2D Double-Quantum Single-Quantum 1H NMR of

2D Double-Quantum Single-Quantum 1H NMR of Elastin
Steven W. Morgan and Gregory S. Boutis
Brooklyn College of The City University of New York, Department of Physics
Elastin is a notoriously unstructured protein made up of cross-links of tropoelastin [1]. We have used 2D double quantum
filtered (DQF) 1H NMR to probe interactions between protons in purified bovine elastin [2]. We apply a double-quantum
single-quantum pulse sequence shown in Fig. 1a [3, 4] and observe two cross peaks between interacting protons (Fig.
1b). The evolution of the cross peaks with double quantum evolution time 2 is shown in Fig. 2. Our preliminary
molecular dynamics simulations indicate that the signals come from Hb (the peak at 1.25 ppm in the direct dimension)
coupled to other protons, presumably alanine Ha. The growth of the DQF signals implies a residual coupling on the order
of 10 Hz for the 3 kHz MAS rate used. We are investigating the nature of this coupling through further NMR experiments
as well as using numerical simulations of small peptides.
π/2
π/2
π
π/2
2.0
1.8
τ
τ
Cross peak intensity (arb.)
1.6
0
1
DQ chemical shift (ppm)
2
3
3.75 ppm cross peak
1.25 ppm cross peak
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0.0
4
0
5
20
40
60
80
100
120
140
160
Time 2 (ms)
6
Figure 2. Single-quantum double-quantum signal
decyas plotted versus evolution time 2. The peak
near a 2 duration of 35 ms indicates a coupling on
the order of 10 Hz. The MAS rate is 3 kHz.
7
8
4
3.5
3
2.5
2
1.5
1
0.5
0
chemical shift (ppm)
Figure 1. (a) NMR pulse sequence to generate
double-quantum single-quantum spectrum. (b)
Representative 2D double quantum-single quantum
proton spectrum of elastin. The delay 2 is 24 ms,
and the MAS rate is 3 kHz.
References
1. J. Rosenbloom, W. R. Abrams, and R. Mecham, FASEB J., 7, 1208 (1993).
2. S. M. Partrige, H. F. Davis, and S. T. Adair, Biochem J., 61, 11, (1955).
3. A. Bax, R. Freeman, and S. P. Kempsell, J. Am. Chem. Soc., 102, 4849 (1980).
4. M. Deschamps, F. Fayon, S. Cadars, A.-L. Rollet, and D. Massiot, Phys. Chem. Chem. Phys. 13, 8024 (2011).

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