Inhibition of calpain in intact platelets by the thiol protease inhibitor E-64d
EB McGowan, E Becker, TC Detwiler - Biochemical and biophysical …, 1989 - Elsevier
EB McGowan, E Becker, TC Detwiler
Biochemical and biophysical research communications, 1989•ElsevierE-64d, a membrane permeant derivative of E-64c, a thiol protease inhibitor (Tamai et
al.(1986) J. Pharmacobio-Dyn. 9, 672–677), was tested for ability to inhibit calpain activity in
intact platelets. Calpain activity was measured by proteolysis of actin-binding protein and
talin, two known substrates of calpain. Incubation of platelets with E-64c (not permeant) or E-
64d before lysis prevented proteolysis after lysis. When the platelets were incubated with E-
64c or E-64d and then washed to remove the drugs before lysis, only E-64d inhibited …
al.(1986) J. Pharmacobio-Dyn. 9, 672–677), was tested for ability to inhibit calpain activity in
intact platelets. Calpain activity was measured by proteolysis of actin-binding protein and
talin, two known substrates of calpain. Incubation of platelets with E-64c (not permeant) or E-
64d before lysis prevented proteolysis after lysis. When the platelets were incubated with E-
64c or E-64d and then washed to remove the drugs before lysis, only E-64d inhibited …
Summary
E-64d, a membrane permeant derivative of E-64c, a thiol protease inhibitor (Tamai et al. (1986) J. Pharmacobio-Dyn.9, 672–677), was tested for ability to inhibit calpain activity in intact platelets. Calpain activity was measured by proteolysis of actin-binding protein and talin, two known substrates of calpain. Incubation of platelets with E-64c (not permeant) or E-64d before lysis prevented proteolysis after lysis. When the platelets were incubated with E-64c or E-64d and then washed to remove the drugs before lysis, only E-64d inhibited proteolysis. When platelets were incubated with E-64c or E-64d and then activated with A23187 plus calcium, a treatment that activates intraplatelet calpain, only E-64d inhibited proteolysis. These results indicate that E-64d can enter the intact cell and inhibit calpain.
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