SAXS and Scatter
SAXS and Scatter
SAXS and Scatter
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Porod Invariant<br />
Assessing flexibility<br />
Q = 1<br />
2π 2 ∫ ∞<br />
0<br />
Kratky Plot<br />
q 2 · I(q) dq<br />
• visualization of Q<br />
• used to interpret samples with flexibility<br />
A plot of q 2 • I(q) vs q should show a curve that captures a<br />
defined area, hence the integral.<br />
Defined area means transformed data converges.<br />
Asymptotic behavior predicted by Debye<br />
equation for a Gaussian r<strong>and</strong>om coil<br />
RNA riboswitch (+/- Mg 2+ )<br />
flexible-unfolded<br />
compact-folded<br />
Defined, captured area<br />
predicted by Q<br />
q, Å<br />
Unfolded particle does not capture a defined area (flexible, unfolded, gaussian chain like)<br />
Folded particle converges at higher q in Kratky plot (folded, compact particle)<br />
Thursday, August 1, 13
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