Identification of the active site for sialogogic peptides

n端氨基酸残基对唾液分泌的调节作用可能非常复杂。当c端七肽具有较强活性时，n端1位和2位的氨基酸残基可作为强抑制剂，而当c端七肽活性较低或无活性时，它们可作为激活剂。此外，c端七肽的唾液活性可能受到非肽中编号为5,6和8位的氨基酸残基的强烈调节。

The regulatory roles for salivation by the N-terminal amino acid residues could be very complicated. When the C-terminal heptapeptides has strong activities, the amino acid residues of the N-terminal portion in positions 1 and 2 could serve as the strong inhibitors, whereas they could serve as the activators when the C-terminal heptapeptides are less active or inactive. In addition, the sialogogic activity of the C-terminal heptapeptides could strongly be regulated with the amino acid residues in positions 5, 6 and 8 numbering as in an undecapeptide.