bcmb8190_p7_10

bcmb8190_p7_10 - c How would you interpret the low T 1...

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BCMB/CHEM 8190 PROBLEM SET 7 1) The following are planes from HNCA and NHCO experiments taken at the same 15 N chemical shift. a) add the residue number to the peaks in the HNCA spectrum b) why are the upfield peaks in each pair weaker? c) will the weaker peaks always be upfield? 2) Below we show some plots for 15 N T1s and T 2 s for a 21 kDa protein collected at 600 MHz for protons and 25º C. Using the simple formulas given in class estimate the correlation time for the protein using some of the data around residues 30-60. a) Given that the dipolar interaction constant for a H-N pair (dd/4) is 5.85 x 10 9 , calculate the order parameter S for these residues (note: a factor of 2/5 was left out of the J( ω ) expression – now corrected). b) If S were 0.8 and the fast motions of the H-N vector were associated with wobbling around the surface of a cone, what would be the cone angle?
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Unformatted text preview: c) How would you interpret the low T 1 values around residue 145? T 1 (ms) T 2 (ms) Sequence Sequence 3) The splitting of a doublet for an amide proton - amide nitrogen pair in an HSQC spectrum that is proton coupled in the nitrogen dimension is measured as 94 Hz under isotropic conditions and 73 Hz under aligned conditions. What is the magnitude of the residual dipolar coupling for this pair? What is the sign of the coupling? 4) A solids NMR spectrum is acquired with magic angle spinning to remove the effects of a 13 C CSA powder pattern that is 200 ppm wide. However, the magic angle is inadvertently set at 50 degrees instead of the magic angle. How wide would you expect the residual line to be in ppms? How wide in Hz in a spectrometer operating at 500 MHz for protons?...
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This note was uploaded on 11/07/2011 for the course CHEM 8853R taught by Professor Gelbaum during the Fall '11 term at Georgia Tech.

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bcmb8190_p7_10 - c How would you interpret the low T 1...

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