13C natural abundance S3E and S3CT experiments for measurement of J coupling constants between 13Calpha or 1Halpha and other protons in a protein.
It is demonstrated that the spin-state-selective pulse sequence elements, S3E and S3CT, previously introduced for measurement of J coupling constants in 15N-labeled proteins can be applied for work with peptides and proteins with 13C at the natural abundance level. In addition, a method is described for suppression of crosstalk caused by passive spin flips and pulse imperfections, which otherwise results in systematically underestimated J coupling constants and thereby inaccurate structural constraints. This method is also applicable for crosstalk suppression in applications of S3E and S3CT to 13C- or 15N-labeled samples. Experimental confirmation is obtained using a 10 mM BPTI sample focusing on 13C in the alpha position. The measured J coupling constants include 3J(HN-Halpha) and 3J(Halpha-Hbeta) related to the phi and chi1 angles, respectively.
Sørensen
M D
MD
Department of Chemistry, Carlsberg Laboratory, Gamle Carlsberg Vej 10, Valby, DK-2500, Denmark.
Meissner
A
A
Sørensen
O W
OW
D002247:Carbon Isotopes / Q000032:analysis; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D015394:Molecular Structure; D009587:Nitrogen Isotopes / Q000032:analysis; D010455:Peptides / Q000737:chemistry; D011506:Proteins / Q000737:chemistry*; D011522:Protons; D013113:Spin Labels
D002247:Carbon Isotopes; D009587:Nitrogen Isotopes; D010455:Peptides; D011506:Proteins; D011522:Protons; D013113:Spin Labels