Induction of salivary kallikreins by the diet containing a sweet-suppressive peptide, gurmarin, in the rat.
Gymnema sylvestre (gymnema) contains gurmarin that selectively inhibits responses to sweet substances in rodents. The present study investigated possible interaction between gurmarin and the submandibular saliva in rats fed diet containing gymnema. Electrophoretic analyses demonstrated that relative amounts of two proteins in the saliva clearly increased in rats fed the gymnema diet. However, rats previously given section of the bilateral glossopharyngeal nerve showed no such salivary protein induction. Analyses of amino acid sequence indicate that two proteins are rat kallikrein 2 (rK2) and rat kallikrein 9 (rK9). rK2 and rK9, a family of serine proteases, have a striking resemblance of cleavage site in the protein substrates. Interestingly, gurmarin possesses comparable residues with those rK2 and rK9 prefer. The kallikreins significantly inhibited immunoreaction between gurmarin and antigurmarin antiserum. These results suggest that rK2 and rK9 increased by chemosensory information for the gymnema diet via the glossopharyngeal nerve might cleave gurmarin or at least cause specific binding with it.
Yamada
Ayako
A
Section of Oral Neuroscience, Graduate School of Dental Sciences, Kyushu University, Higashi-ku, Fukuoka, Japan.
Nakamura
Yuki
Y
Sugita
Daigo
D
Shirosaki
Shinya
S
Ohkuri
Tadahiro
T
Katsukawa
Hideo
H
Nonaka
Kazuaki
K
Imoto
Toshiaki
T
Ninomiya
Yuzo
Y
D000595:Amino Acid Sequence; D000818:Animals; D000906:Antibodies / Q000276:immunology; D003864:Depression, Chemical; D004032:Diet; D004790:Enzyme Induction; D005930:Glossopharyngeal Nerve / Q000502:physiology; D031103:Gymnema / Q000737:chemistry*; D007610:Kallikreins / Q000378:metabolism*; D008297:Male; D010940:Plant Proteins / Q000276:immunology / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D012463:Saliva / Q000187:drug effects* / Q000201:enzymology; D013649:Taste / Q000187:drug effects*; D020840:Tissue Kallikreins / Q000096:biosynthesis*
D000906:Antibodies; D010940:Plant Proteins; C075206:Gurmarin protein, Gymnema sylvestre; D007610:Kallikreins; D020840:Tissue Kallikreins