Complete 1H, 13C and 15N NMR assignments and secondary structure of the 269-residue serine protease PB92 from Bacillus alcalophilus

Abstract

The 1H, 13C and 15N NMR resonances of serine protease PB92 have been assigned using 3D triple-resonance NMR techniques. With a molecular weight of 27 kDa (269 residues) this protein is one of the largest monomeric proteins assigned so far. The side-chain assignments were based mainly on 3D H(C)CH and 3D (H)CCH COSY and TOCSY experiments. The set of assignments encompasses all backbone carbonyl and CHn carbons, all amide (NH and NH2) nitrogens and 99.2% of the amide and CHn protons. The secondary structure and general topology appear to be identical to those found in the crystal structure of serine protease PB92 [Van der Laan et al. (1992) Protein Eng., 5, 405-411], as judged by chemical shift deviations from random coil values, NH exchange data and analysis of NOEs between backbone NH groups.