title: The marine cyanobacterial metabolite gallinamide A is a potent and selective inhibitor of human cathepsin L.
abstract: A number of marine natural products are potent inhibitors of proteases, an important drug target class in human diseases. Hence, marine cyanobacterial extracts were assessed for inhibitory activity to human cathepsin L. Herein, we have shown that gallinamide A potently and selectively inhibits the human cysteine protease cathepsin L. With 30 min of preincubation, gallinamide A displayed an IC50 of 5.0 nM, and kinetic analysis demonstrated an inhibition constant of ki = 9000 ± 260 M(-1) s(-1). Preincubation-dilution and activity-probe experiments revealed an irreversible mode of inhibition, and comparative IC50 values display a 28- to 320-fold greater selectivity toward cathepsin L than closely related human cysteine cathepsin V or B. Molecular docking and molecular dynamics simulations were used to determine the pose of gallinamide in the active site of cathepsin L. These data resulted in the identification of a pose characterized by high stability, a consistent hydrogen bond network, and the reactive Michael acceptor enamide of gallinamide A positioned near the active site cysteine of the protease, leading to a proposed mechanism of covalent inhibition. These data reveal and characterize the novel activity of gallinamide A as a potent inhibitor of human cathepsin L.
authors.affiliation: Center for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, University of California, San Diego , La Jolla, California 92093, United States.
authors.forename: Bailey
authors.initials: B
authors.lastname: Miller
authors.forename: Aaron J
authors.initials: AJ
authors.lastname: Friedman
authors.forename: Hyukjae
authors.initials: H
authors.lastname: Choi
authors.forename: James
authors.initials: J
authors.lastname: Hogan
authors.forename: J Andrew
authors.initials: JA
authors.lastname: McCammon
authors.forename: Vivian
authors.initials: V
authors.lastname: Hook
authors.forename: William H
authors.initials: WH
authors.lastname: Gerwick
mesh_terms: D000595:Amino Acid Sequence; D023181:Antimicrobial Cationic Peptides; D020134:Catalytic Domain; D056668:Cathepsin L / Q000037:antagonists & inhibitors* / Q000378:metabolism; D000458:Cyanobacteria / Q000737:chemistry*; D006801:Humans; D020128:Inhibitory Concentration 50; D007700:Kinetics; D008386:Marine Biology; D015394:Molecular Structure; D010455:Peptides / Q000737:chemistry / Q000494:pharmacology*; D011480:Protease Inhibitors / Q000302:isolation & purification / Q000494:pharmacology*
chemical_list: D023181:Antimicrobial Cationic Peptides; D010455:Peptides; D011480:Protease Inhibitors; C534687:gallinamide A; D056668:Cathepsin L