Structural determination of the active site of a sweet protein. A 1H NMR investigation of pMNEI.
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.
Tancredi
T
T
ICMIB, CNR, Napoli, Italy.
Iijima
H
H
Saviano
G
G
Amodeo
P
P
Temussi
P A
PA
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*
D010940:Plant Proteins; D013549:Sweetening Agents; C002541:monellin protein, Dioscoreophyllum cumminsii