1mnl
From Proteopedia
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HIGH-RESOLUTION SOLUTION STRUCTURE OF A SWEET PROTEIN SINGLE-CHAIN MONELLIN (SCM) DETERMINED BY NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY AND DYNAMICAL SIMULATED ANNEALING CALCULATIONS, 21 STRUCTURES
Overview
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 (<SA>k) converged, well with a root-mean-square deviation (rmsd) between backbone atoms of, 0.49 A for secondary structural regions and 0.70 A for backbone atoms, excluding two loop regions. The average restraint energy-minimized (REM), structure exhibited root-mean-square deviations of 1.19 A for backbone, atoms and 0.85 A for backbone atoms excluding two loop regions with, respect to 20 <SA>k structures. The solution structure of SCM revealed, that the long alpha-helix was folded into the concave side of a, six-stranded antiparallel beta-sheet. The side chains of Tyr63 and Asp66, which are common to all sweet peptides showed an opposite orientation, relative to H1 helix, and they were all solvent-exposed. Residues at the, proposed dimeric interface in the X-ray structure were observed to be, mostly solvent-exposed and demonstrated high degrees of flexibility.
About this Structure
1MNL is a Single protein structure of sequence from Dioscoreophyllum cumminsii. Full crystallographic information is available from OCA.
Reference
Solution structure of a sweet protein single-chain monellin determined by nuclear magnetic resonance and dynamical simulated annealing calculations., Lee SY, Lee JH, Chang HJ, Cho JM, Jung JW, Lee W, Biochemistry. 1999 Feb 23;38(8):2340-6. PMID:10029527
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