Home Life Sciences Recombinant Cryptic Human Fibronectinase Cleaves Actin and Myosin: Substrate Specificity and Possible Role in Muscular Dystrophy
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Recombinant Cryptic Human Fibronectinase Cleaves Actin and Myosin: Substrate Specificity and Possible Role in Muscular Dystrophy

  • Jörn Schnepel , Jens Unger and Harald Tschesche
Published/Copyright: June 1, 2005
Biological Chemistry
From the journal Volume 382 Issue 12

Abstract

The Nterminal heparin/fibrin binding domain of human plasma fibronectin (pFN) contains a cryptic proteinase. The enzyme could be generated and activated in the presence of Ca 2+ from the purified 70 kDa pFN fragment produced by cathepsin D digestion of pFN. In this work we cloned and expressed the serine proteinase, designated fibronectinase (Fnase), in E. coli. The recombinant pFN protein fragment was isolated from inclusion bodies, subjected to folding and autocatalytic degradation in the presence of Ca 2+ , and yielded an active enzyme capable of digesting fibronectin. Cleavage of pFN and the synthetic peptides AcIEGKpNA and BzIEGRpNA demonstrated identical specificity of the recombinant and the isolated fibronectinase. Further investigations of the substrate specificity revealed for the first time the muscle proteins actin and myosin as being substrates of fibronectinase. The enzyme can be inhibited by α1-proteinase inhibitor. In the context of induced cathepsin D release, e. g. from granulocytes under inflammatory conditions, these results indicate an increase in specific proteolytic potential against muscular proteins in dystrophic diseases by the release of cryptic fibronectinase.

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Published Online: 2005-06-01
Published in Print: 2001-12-19

Copyright © 2001 by Walter de Gruyter GmbH & Co. KG

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