title: Assignment of the protonated 13C resonances of apo-neocarzinostatin by 2D heteronuclear NMR spectroscopy at natural abundance.
abstract: Nearly complete assignment of the protonated carbon resonances of apo-neocarzinostatin, a 113-amino acid antitumor antibiotic carrier protein, has been achieved at natural 13C abundance using heteronuclear 2D experiments. Most of the cross peaks in the proton-carbon correlation map were identified by the combined use of HMQC, HMQC-RELAY and HMQC-NOESY spectra, using already published proton chemical shifts. However, double-DEPT and triple-quantum experiments had to be performed for the edition of CH and CH2 side-chain groups, respectively, which were hardly visible on HMQC-type maps. The triple-quantum pulse sequence was adapted from its original scheme to be applicable to a natural abundance sample. The correlation between carbon chemical shifts and the apo-neocarzinostatin structure is discussed. In particular, 13C alpha secondary shifts correlate well with the backbone conformation. These shifts also yield information about the main-chain flexibility of the protein. Assignments reported herein will be used further for interpretation of carbon relaxation times in a study of the internal dynamics of apo-neocarzinostatin.
authors.affiliation: U350 INSERM, Institut Curie Biologie, Centre Universitaire, Orsay, France.
authors.forename: C
authors.initials: C
authors.lastname: Lefevre
authors.forename: E
authors.initials: E
authors.lastname: Adjadj
authors.forename: E
authors.initials: E
authors.lastname: Quiniou
authors.forename: J
authors.initials: J
authors.lastname: Mispelter
mesh_terms: D000595:Amino Acid Sequence; D001059:Apoproteins / Q000737:chemistry*; D002247:Carbon Isotopes; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008969:Molecular Sequence Data; D011522:Protons; D009353:Zinostatin / Q000737:chemistry*
chemical_list: D001059:Apoproteins; D002247:Carbon Isotopes; D011522:Protons; C052401:aponeocarzinostatin; D009353:Zinostatin