Enhancement of thrombin receptor activation by thrombin receptor-derived heptapeptide with para-fluorophenylalanine in place of phenylalanine.
Thrombin receptor-derived peptide SFLLRNP (one-letter amino acid code) which corresponds to the N-terminal heptapeptide of tethered ligand is able to activate thrombin receptor and to stimulate the phosphoinositide (PI) turnover. The replacement of Phe-2 by Ala eliminated this activity completely, showing the crucial role of the Phe-phenyl group in receptor activation. It was found that substitution of para-fluorophenylalanine ((p-F)Phe) for Phe-2 enhanced several times the PI-turnover activity of SFLLRNP. This is the first example to date of a substitution with one order of magnitude greater increase in receptor activation. The Phe-2/Tyr substitution diminished the activity drastically (almost 2% of SFLLRNP), indicating the importance of hydrophobicity of Phe2-phenyl. The Phe-2/Leu substitution, however, diminished also the activity (less than 2% of SFLLRNP). These results suggested that highly specific hydrophobic interaction exists between Phe-2 of the tethered ligand and its binding site in thrombin receptor.
Department of Chemistry, Faculty of Science, Kyushu University, Fukuoka, Japan.
T
T
Nose
Y
Y
Shimohigashi
M
M
Ohno
T
T
Costa
N
N
Shimizu
Y
Y
Ogino
D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D002942:Circular Dichroism; D004848:Epithelium; D007202:Indicators and Reagents; D007294:Inositol / Q000378:metabolism; D007700:Kinetics; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000138:chemical synthesis / Q000494:pharmacology*; D010649:Phenylalanine; D010716:Phosphatidylinositols / Q000378:metabolism*; D011956:Receptors, Cell Surface / Q000187:drug effects* / Q000378:metabolism; D018179:Receptors, Thrombin; D013329:Structure-Activity Relationship; D013917:Thrombin / Q000378:metabolism; D010135:p-Fluorophenylalanine
D007202:Indicators and Reagents; D010446:Peptide Fragments; D010716:Phosphatidylinositols; D011956:Receptors, Cell Surface; D018179:Receptors, Thrombin; D010649:Phenylalanine; D007294:Inositol; D010135:p-Fluorophenylalanine; D013917:Thrombin