Assignment of the protonated 13C resonances of apo-neocarzinostatin by 2D heteronuclear NMR spectroscopy at natural abundance.
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.
Lefevre
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C
U350 INSERM, Institut Curie Biologie, Centre Universitaire, Orsay, France.
Adjadj
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Quiniou
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Mispelter
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J
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*
D001059:Apoproteins; D002247:Carbon Isotopes; D011522:Protons; C052401:aponeocarzinostatin; D009353:Zinostatin