Solution structure of a sweet protein single-chain monellin determined by nuclear magnetic resonance and dynamical simulated annealing calculations.

Single-chain monellin (SCM), which is an engineered 94-residue polypeptide, has proven to be as sweet as native two-chain monellin. SCM is more stable than the native monellin for both heat and acidic environments. Data from gel filtration HPLC and NMR indicate that the SCM exists as a monomer in aqueous solution. The solution structure of SCM has been determined by nuclear magnetic resonance (NMR) spectroscopy and dynamical simulated annealing calculations. A stable alpha-helix spanning residues Phe11-Ile26 and an antiparallel beta-sheet formed by residues 2-5, 36-38, 41-47, 54-64, 69-75, and 83-88 have been identified. The sheet was well defined by backbone-backbone NOEs, and the corresponding beta-strands were further confirmed by hydrogen bond networks based on amide hydrogen exchange data. Strands beta2 and beta3 are connected by a small bulge comprising residues Ile38-Cys41. A total of 993 distance and 56 dihedral angle restraints were used for simulated annealing calculations. The final simulated annealing structures (

Duke Scholars

Author Seok-Yong Lee Biochemistry