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Hello, I am trying to determine solution structure of a peptide in 50% trifluoroethanol(TFE) solution. I dissolved my peptide in 50% TFE-d3/50%H2O solution. When I enter "lock" on command table, I cannot find lock value on this solvent. (I am bruker 600 Hz NMR and using topspin 2.1 software). I tried to select TFE on the lock table, but the lock signal was wobbling too much and the line shape was not good. I tried to find lock value of 50% TFE on the internet, but I could not find. In this case, how should I do? I hope someone could me suggest any ideas about this. Thank you very much. Glenn |
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You can optimize the lock by first increasing the lock power by say 3 db's then run the auto lock phase and shimming, if you get a good low noise lock save the values in the edlock table, you may also have to create a new solvent first, if the lock doesn't get to a low enough noise level the you can up the lock power again, at some point you may see signs of saturation of the lock signal where the lock bounces up and down, stay at least a couple of fb below that power. |
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Rather than using 'lock' command, you might first lock the solvent manually, then enter the correct lock parameters in edlock. If the lock signal bounces up and down, then lock power is likely too high. - Jerry Hirschinger (Jul 16 '12 at 08:10)