Developing peptide inhibitors to thrombin activation of platelets from bradykinin analogs.
Investigations identified peptide, platelet-selective thrombin inhibitors. Three peptides (MAP4-RPPGF, RGKWC and RGDWC) were relatively selective inhibitors of thrombin-induced platelet activation and calcium mobilization. MAP4-RPPGF at 35.5+/-0.03 microM inhibits gamma-thrombin-induced platelet aggregation 100% and alpha-thrombin-induced calcium mobilization in fibroblasts 84%. RGKWC at 800+/-400 microM inhibits gamma-thrombin-induced platelet aggregation 100% and calcium mobilization 63%. RGDWC at 140+/-100 microM inhibits gamma-thrombin-induced platelet aggregation 100% and calcium mobilization 32%. RGDWC also inhibits ADP-induced platelet aggregation, whereas MAP4-RPPGF and RGKWC do not. RGKWC prolongs the activated partial thromboplastin time (APTT) but not the prothrombin time (PT) or thrombin clotting time (TCT). RGKWC uniquely inhibits alpha-thrombin activation of human factor XI. Single amino acid substitutions in peptide pentamers result in differences in potency and mechanism(s) of inhibition of platelet and fibroblast activation by thrombin.
Hasan
A A
AA
Thromgen, Inc., Ann Arbor, MI 48104, USA.
Warnock
M
M
Srikanth
S
S
Schmaier
A H
AH
D000244:Adenosine Diphosphate / Q000494:pharmacology; D000595:Amino Acid Sequence; D001780:Blood Coagulation Tests; D001920:Bradykinin / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000494:pharmacology; D020013:Calcium Signaling / Q000187:drug effects; D020650:Combinatorial Chemistry Techniques; D004305:Dose-Response Relationship, Drug; D015195:Drug Design; D006801:Humans; D009842:Oligopeptides / Q000138:chemical synthesis / Q000494:pharmacology*; D019151:Peptide Library; D015539:Platelet Activation / Q000187:drug effects*; D013329:Structure-Activity Relationship; D013917:Thrombin / Q000037:antagonists & inhibitors* / Q000494:pharmacology / Q000502:physiology
D009842:Oligopeptides; D019151:Peptide Library; D000244:Adenosine Diphosphate; D013917:Thrombin; D001920:Bradykinin