Kinetic constants of signal peptidase I using cytochrome b5 as a precursor substrate

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dc.contributor.author Gallagher, Joseph Anthony
dc.contributor.author Kaderbhai, Naheed N.
dc.contributor.author Kaderbhai, Mustak A.
dc.date.accessioned 2008-12-04T14:41:03Z
dc.date.available 2008-12-04T14:41:03Z
dc.date.issued 2001-11-26
dc.identifier.citation Gallagher , J A , Kaderbhai , N N & Kaderbhai , M A 2001 , ' Kinetic constants of signal peptidase I using cytochrome b5 as a precursor substrate ' Biochimica et Biophysica Acta (BBA) - Protein Structure and Molecular Ezymology , vol 1550 , no. 1 , pp. 1-5 . en
dc.identifier.issn 0167-4838
dc.identifier.other PURE: 94133
dc.identifier.other dspace: 2160/1350
dc.identifier.uri http://hdl.handle.net/2160/1350
dc.description Gallagher, J. A., Kaderbhai, N., Kaderbhai, M. (2001). Kinetic constants of signal peptidase I using cytochrome b5 as a precursor substrate. Biochimica et Biophysica Acta - Protein Structure and Molecular Enzymology, 1550 (1), 1-5. Sponsorship: BBSRC RAE2008 en
dc.description.abstract A procedure is described for measuring Escherichia coli signal peptidase I activity which exploits an intact precursor protein composed of the alkaline phosphatase signal peptide fused to the full length mammalian cytochrome b5. This cytochrome b5 precursor protein has been extensively characterised and shown to be processed accurately by purified signal peptidase I [Protein Expr. Purif. 7 (1996) 237]. The amphipathic, chimaeric cytochrome b5 precursor was isolated in mg quantities in a highly homogeneous state under non-denaturing conditions. The processing of the cytochrome b5 precursor by signal peptidase displayed Michaelis–Menten kinetics with Km=50 μM and kcat=11 s−1. The Km was 20-fold lower than that obtained with signal peptide substrates and 3-fold higher than that reported for pro-OmpA-nuclease A precursor fusion. The corresponding turnover number, kcat, was four orders of magnitude greater than the peptide substrates but was 2-fold lower than pro-OmpA-nuclease A precursor fusion. These results confirm that both the affinities and the catalytic power of the signal peptidase are significantly higher for macromolecular precursor substrates than for the shorter signal peptide substrates. en
dc.format.extent 5 en
dc.language.iso eng
dc.relation.ispartof Biochimica et Biophysica Acta (BBA) - Protein Structure and Molecular Ezymology en
dc.title Kinetic constants of signal peptidase I using cytochrome b5 as a precursor substrate en
dc.type Text en
dc.type.publicationtype Article (Journal) en
dc.identifier.doi http://dx.doi.org/10.1016/S0167-4838(01)00265-5
dc.contributor.institution Institute of Biological, Environmental and Rural Sciences en
dc.description.status Peer reviewed en


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