Jan S Keruchenko

Russian Academy of Sciences, Moskva, Moscow, Russia

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Publications (4)11.62 Total impact

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    ABSTRACT: Mechano-growth factor (MGF) is a product of a unique muscle-specific splice variant of the insulin-like growth factor I gene. Potential use of MGF to improve regenerative capability of skeletal muscle as well as to prevent neuronal damage has been widely discussed. Human MGF was expressed in Saccharomyces cerevisiae, but the yield of the recombinant protein was low due to its rapid degradation. The proteinase B was identified as the enzyme responsible for MGF processing. A yeast strain with Deltaprb1 deletion was created resulting in a fivefold increase of MGF yield that reached 50 mg/l. The biological activity of recombinant MGF was verified in a proliferation assay employing human postnatal myoblasts.
    Journal of Molecular Microbiology and Biotechnology 01/2010; 18(3):188-94. DOI:10.1159/000315460
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    ABSTRACT: MGF is a product of a unique muscle-specific splice variant of IGF1 gene (insulin-like growth factor). Its peculiar feature is a specific E-peptide, a 16 a.a. strand at the C-terminus. MGF increases cellular proliferation and inhibits terminal differentiation of myoblasts necessary for the secondary myotube formation. Previous analysis of physiological effects of MGF was performed using indirect methods such as RT-PCR based examination of the transcript contents in normal tissues, adenovirus-mediated DNA delivery and synthetic E-domain administration. Here, we describe isolation and purification of recombinant MGF thus allowing for the first time the possibility of direct examining MGF effects. The recombinant MGF of directly examining--was expressed in Escherichia coli as inclusion bodies (about 100-200mg/l), purified and refolded. Biological activity of refolded MGF was analyzed in vitro in proliferation assays with normal human myoblasts. As a result of our work, it has become possible to generate a standard MGF control with characterized activity and a ready-to use MGF test-system neither of which have been previously described. Our data open opportunities for the future works on MGF characterization and to the development of a powerful and highly specific therapeutic agent potentially applicable for muscle growth up-regulation, post-trauma muscle repair, age and hereditary myodystrophy mitigation and in sport medicine.
    Protein Expression and Purification 04/2008; 58(1):70-7. DOI:10.1016/j.pep.2007.10.023
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    ABSTRACT: Crystal structures for both native and recombinant forms of yeast fumarase from Saccharomyces cerevisiae have been completed to moderate resolution by two separate laboratories. The recombinant form was obtained by the construction of an expression plasmid for Escherichia coli. Despite a high level of amino acid sequence similarity, purification of the eukaryotic enzyme from the wild-type prokaryotic enzyme was feasible. The crystal structure of the native form, NY-fumarase, encompasses residues R22 through M484, while the recombinant form, RY-fumarase, consists of residues S27 through L485. Both crystal structures lack the N-terminal translocation segment. Each subunit of the homo-tetrameric protein has three domains. The active site is formed by segments from each of three polypeptide chains. The results of these studies on the eukaryotic proteins are unique, since the recombinant form was done in the absence of dicarboxylic acid and has an unoccupied active site. As a comparison, native fumarase was crystallized in the presence of the competitive inhibitor, meso-tartrate. Meso-tartrate occupies a position close to that of the bound citrate molecule found in the active site of the E. coli enzyme. This inhibitor participates in hydrogen bonding to an active-site water molecule. The independent determination of the two structures provides further evidence that an active-site water molecule may play an active role in the fumarase-catalyzed reaction.
    Journal of Molecular Biology 08/1998; 280(3):431-42. DOI:10.1006/jmbi.1998.1862
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    ABSTRACT: Fumarase (fumarate hydratase, EC 4.2.1.2) from Saccharomyces cerevisiae has been purified to homogeneity by a method including acetone fractionation, DEAE ion-exchange and dye-sorbent affinity chromatography. The suggested method allows fumarase purification with a yield higher than 60% and may be used to obtain large enzyme quantities. The native protein consists of four subunits with a approximately 50 kDa molecular mass each and has an isoelectric point at pH 6.5 +/- 0.3. The equilibrium constant for fumarate hydration is about 4.3 (25 degrees C, pH 7.5), the Michaelis constants for fumarate and 1-malate are approximately 30 microM and approximately 250 microM, respectively. The enzyme is activated by substrates and multivalent anions, the activation seems to be of a non-competitive type. The fumarase complex with meso-tartaric acid has been crystallized by the vapor diffusion method. The unit cell parameters are a = 93.30, b = 94.05 and c = 106.07 A, space group P2(1)2(1)2(1). The unit cell contains 2 protein molecules. The crystals diffract to at least 2.6 A resolution and are suitable for X-ray structure analysis.
    Biochimica et Biophysica Acta 08/1992; 1122(1):85-92. DOI:10.1016/0167-4838(92)90131-V