Aminopeptidase resistant Arg-Gly-Asp analogs are stable in plasma and inhibit platelet aggregation.
Tetrapeptides containing the sequence Arg-Gly-Asp (RGD) antagonize fibrinogen binding to its platelet receptor (gp IIb/IIIa, integrin alpha IIb beta 3) and inhibit platelet aggregation in vitro. The peptides RGDS and RGDY(Me)-NH2 were rapidly degraded when incubated in human, rat, and dog plasma. HPLC analysis indicated that amino acids were sequentially removed from the peptide N-terminus, and this degradation was prevented by the aminopeptidase inhibitor bestatin. Analogs of RGDY(Me)-NH2 with an acetylated or deleted alpha-amino group were prepared. Both analogs were stable when incubated in plasma, blocked 125I-fibrinogen binding to activated platelets (IC50 = 10-30 microM) and inhibited ADP induced platelet aggregation (IC50 = 10-30 microM). This study concludes that aminopeptidase rapidly degrades RGD peptides in plasma, an important issue for in vivo testing of RGD peptides and analogs. RGD analogs intrinsically stabilized against aminopeptidase are stable in plasma and are important tools for antithrombotic studies involving antagonism of gp IIb/IIIa.
Fok
K F
KF
Corporate Research Department, Monsanto Company, St. Louis, Missouri, MO.
Panzer-Knodle
S G
SG
Nicholson
N S
NS
Tjoeng
F S
FS
Feigen
L P
LP
Adams
S P
SP
D000595:Amino Acid Sequence; D000626:Aminopeptidases / Q000494:pharmacology*; D001665:Binding Sites / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D005340:Fibrinogen / Q000037:antagonists & inhibitors; D016023:Integrins / Q000037:antagonists & inhibitors; D008969:Molecular Sequence Data; D010974:Platelet Aggregation / Q000187:drug effects*; D010975:Platelet Aggregation Inhibitors / Q000378:metabolism / Q000494:pharmacology*; D010980:Platelet Membrane Glycoproteins / Q000037:antagonists & inhibitors*; D011971:Receptors, Immunologic; D018000:Receptors, Peptide
D016023:Integrins; D010975:Platelet Aggregation Inhibitors; D010980:Platelet Membrane Glycoproteins; D011971:Receptors, Immunologic; D018000:Receptors, Peptide; C051382:arginyl-glycyl-aspartic acid directed cell adhesion receptor; D005340:Fibrinogen; D000626:Aminopeptidases