The complete amino-acid sequence of the sweet protein thaumatin I.
The primary structure of the sweet-tasting protein thaumatin has been elucidated. The protein consists of a single polypeptide chain of 207 residues. The sequence of the N-terminal part of the chain was determined by sequenator analysis. As the protein contains only one methionine residue, it was possible to deduce the N-terminal sequence of the C-terminal cyanogen bromide fragment by automatic sequencing of the cyanogen-bromide-cleaved, succinylated protein. To arrive at the sequence of the whole protein tryptic and Staphylococcus protease peptides, together with chymotryptic peptides and a 2-(2-nitrophenylsulfenyl)-3-methyl-3'-bromoindolenine (BNPS-skatole) fragment were also sequenced. Comparing the amino acid sequence of thaumatin with that of the other sweet-tasting protein, monellin, we have located five sets of identical tripeptides. Since immunological cross-reactivity of thaumatin antibodies with monellin has recently been described, one or more of these tripeptides might be part of a common antibody recombination site and possibly be involved in the interaction with the sweet-taste receptor.
D000595:Amino Acid Sequence; D002918:Chymotrypsin; D010446:Peptide Fragments / Q000032:analysis; D010447:Peptide Hydrolases; D010940:Plant Proteins; D013549:Sweetening Agents; D014357:Trypsin
D010446:Peptide Fragments; D010940:Plant Proteins; D013549:Sweetening Agents; D010447:Peptide Hydrolases; D002918:Chymotrypsin; D014357:Trypsin