title: Synthesis of peptides of arginine chloromethyl ketone. Selective inactivation of human plasma kallikrein.
abstract: Synthetic procedures have been developed for the preparation of peptides of arginine chloromethyl ketone and applied in the preparation of affinity labels which correspond to the -Pro-Phe-Arg- C terminus of bradykinin, a physiological cleavage site of kallikrein in kininogen. Two such reagents, Ala-Phe-ArgCH2C1 and Pro-Phe-ArgCH2C1, proved to be highly effective as well as selective affinity labels for human plasma kallikrein. For example, Pro-Phe-ArgCH2C1 inactivates plasma kallikrein 50% in 24 min at a concentration of 2 x 10(-8)M, while other trypsin-like proteases are less susceptible in inactivation than kallikrein, differing by a factor of 48 for plasmin and factors of 10(2)-10(5) for factor Xa, thrombin, and urokinase. The affinity of human plasma kallikrein for Ala-Phe-ArgCH2C1 (Ki = 0.078 micron) is about 60 times that for Ala-Phe-LysCH2C1(Ki = 4.9 micron), whereas human plasmin exhibits about the same affinity for the former affinity label (Ki = 1.3 micron) as for the latter (Ki = 0.83 micron). The rate constants for the irreversible step of the affinity labeling reaction, k2, are similar for affinity labels tested with the individual proteases: 0.35 min-1 for plasma kallikrein and 0.18 min-1 for plasmin.
mesh_terms: D000345:Affinity Labels; D000590:Amino Acid Chloromethyl Ketones / Q000138:chemical synthesis* / Q000494:pharmacology; D006801:Humans; D007610:Kallikreins / Q000037:antagonists & inhibitors* / Q000097:blood; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy; D011480:Protease Inhibitors
chemical_list: D000345:Affinity Labels; D000590:Amino Acid Chloromethyl Ketones; D011480:Protease Inhibitors; D007610:Kallikreins