| Autor: |
Crabbe, Thomas, Ioannou, Chris, Docherty, Andrew J. P. |
| Předmět: |
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| Zdroj: |
European Journal of Biochemistry; 12/1/93, Vol. 218 Issue 2, p431-438, 8p |
| Abstrakt: |
Activation of the latent precursor of human gelatinase A (progelatinase A) was investigated using recombinant proenzyme purified from culture medium conditioned by transfected mouse myeloma cells. A 4.0 μM progelatinase A solution was activated to a maximum of 48% of the activity produced by 4-aminophenylmercuric acetate (APMA) simply by its incubation at 37°C for 12h, though at lower starting concentrations the rate and extent of activation were reduced. Activation was shown to be the result of a single autolytic cleavage at the Asn80-Tyr81 peptide bond that removes the propeptide and converts the Mr = 72000 proenzyme into the Mr = 66000 active species also produced by APMA activation. It is proposed that this cleavage is a bimolecular event catalysed by previously activated gelatinase A. The addition of heparin increased by approximately eightfold the initial rate of progelatinase A autolytic activation but did not affect the activation of a deletion mutant that lacked the C-terminal domain [des-(418–631) gelatinase A, both full-length gelatinase A and the isolated C-terminal domain were able to bind to heparinSepharose CL-6N and that, at NaCl concentrations sufficient to abolish this binding, heparin had no effect. We conclude that heparin is able to enhance autolytic activation by acting as a template that approximates active → latent gelatinase A and suggest that a similar mechanism may account for the cell-surface activation of this enzyme. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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