Neocarzinostatin: selective tryptophan oxidation and neocarzinostatin-chromophore binding to apo-neocarzinostatin.
Neocarzinostatin (NCS), an antitumor protein antibiotic, is composed of apo-neocarzinostatin (apo-NCS) and neocarzinostatin-chromophore (NCS-chr), the principle of the biological activities of NCS. Apo-NCS having two tryptophan (Trp) residues at positions (39 and 83) was chemically modified by N-bromosuccinimide in a study on the correlation of the binding site(s) of NCS-chr. Selective oxidation of Trp residues was observed when NCS was titrated with N-bromosuccinimide. In contrast, non-selective oxidation of the two Trps on apo-NCS was observed and both Trp (39 and 83) of apo-NCS were titrated with N-bromosuccinimide. After selective oxidation, the remaining Trp residue of NCS was assigned as Trp (83). These results clearly indicate that the Trp (83) residue of apo-NCS changed from the "reactive type" to the "non-reactive type" after the binding of NCS-chr with apo-NCS. The fluorescence emission intensity of apo-NCS generated from the Trp (39) residue was quenched by NCS-chr. These data suggest that NCS-chr directly interacts with the Trp (39) residue and that a beta-sheeted loop containing the Trp (83) residue of apo-NCS changes the high-order structure upon binding with NCS-chr.
Edo
K
K
Department of Pharmaceutical Sciences, Tohoku University Hospital, Sendai, Japan.
Saito
K
K
Matsuda
Y
Y
Akiyama-Murai
Y
Y
Mizugaki
M
M
Koide
Y
Y
Ishida
N
N
D000595:Amino Acid Sequence; D001059:Apoproteins / Q000378:metabolism; D008969:Molecular Sequence Data; D010084:Oxidation-Reduction; D011485:Protein Binding; D014364:Tryptophan / Q000378:metabolism*; D009353:Zinostatin / Q000378:metabolism*
D001059:Apoproteins; D014364:Tryptophan; D009353:Zinostatin