Determination of the sign of long-range 1H–13C scalar coupling constants to non-protonated carbons: application to assignment

✍ Scribed by Yasuhiro Kumaki; Kunio Hikichi

• Publisher: John Wiley and Sons
• Year: 1999
• Tongue: English
• Weight: 84 KB
• Volume: 37
• Category: Article
• ISSN: 0749-1581
• DOI: 10.1002/(sici)1097-458x(199906)37:6<413::aid-mrc478>3.0.co;2-u

✦ Synopsis

The sign of the scalar coupling between a carbonyl carbon and ˛-proton J(C 0 ,H ˛), for the cyclic dipeptide cyclo(Leu-Gly) was determined relative to that between an amide proton and ˛-proton 3 J(H N ,H ˛) by an E.COSYtype HSQC experiment. The pulse sequence used in this experiment gives a cross peak between the amide proton and carbonyl carbon which shows an E.COSY-type tilt caused by the ˛-proton. The sign information on J(C 0 ,H ˛) was used to distinguish between two-bond (intra-residue) and three-bond (inter-residue) J(C 0 ,H ˛)s, leading to the assignment of the carbonyl carbons of the cyclic dipeptide cyclo(Leu-Gly).