Facile determination of the protecting group location of Nim-protected histidine derivatives by 1H-15N heteronuclear correlation NMR.
The positioning of the imidazole protecting group of several histidine derivatives was determined by means of (1)H-(15)N heteronuclear multiple-bond correlation NMR experiments. The cross-peak originated from the three-bond correlation between the histidine side-chain H(beta) and the imidazole N(pi) was used for the identification of the N(pi) signal in the (15)N spectrum. Therefore, based on the fact that the signal of the substituted imidazole nitrogen appears always at lower chemical shift (delta) than the unsubstituted one, the position of the blocking group could easily be inferred. The obtained data confirmed previous findings that were accomplished with other less generally applicable spectroscopic or crystallographic techniques.
Zaramella
Simone
S
Division of Organic and Bioorganic Chemistry, MBB, Scheele Laboratory, Karolinska Institutet, SE-17177 Stockholm, Sweden. petheino@utu.fi
Heinonen
Petri
P
Yeheskiely
Esther
E
Strömberg
Roger
R
D020650:Combinatorial Chemistry Techniques; D006639:Histidine / Q000737:chemistry*; D009587:Nitrogen Isotopes; D019906:Nuclear Magnetic Resonance, Biomolecular; D010455:Peptides / Q000138:chemical synthesis
D009587:Nitrogen Isotopes; D010455:Peptides; D006639:Histidine