title: Structural determination of the active site of a sweet protein. A 1H NMR investigation of pMNEI.
abstract: pMNEI, a single chain sweet protein related to monellin, has been studied by means of 1H NMR at 500 MHz. A partial sequential assignment performed by means of the MCD method allowed the determination of the secondary structure of a large portion of the beta-sheet of pMNEI that contains a likely 'sweet finger': the loop connecting the beta-strands from residue 59 to residue 78, corresponding to segment 16-35 of the A chain of monellin. The detailed three-dimensional structure of the loop (Tyr66-Ala67-Ser68-Asp69), determined from several interresidue and intraresidue NOEs and subsequent energy minimization, shows that the side chains of Tyr66 and Asp69 fit our model of the sweet receptor in a manner very similar to that of the side chains of Phe and Asp of aspartame.
authors.affiliation: ICMIB, CNR, Napoli, Italy.
authors.forename: T
authors.initials: T
authors.lastname: Tancredi
authors.forename: H
authors.initials: H
authors.lastname: Iijima
authors.forename: G
authors.initials: G
authors.lastname: Saviano
authors.forename: P
authors.initials: P
authors.lastname: Amodeo
authors.forename: P A
authors.initials: PA
authors.lastname: Temussi
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000737:chemistry*; D011487:Protein Conformation; D013549:Sweetening Agents / Q000737:chemistry*
chemical_list: D010940:Plant Proteins; D013549:Sweetening Agents; C002541:monellin protein, Dioscoreophyllum cumminsii