Enzymatic activities of mouse vas deferens protein : reduction of aldehydes and steroidal compounds

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Enzymatic activities of mouse vas deferens protein : reduction of aldehydes and steroidal compounds


Author: Kwok, Ka-yin
Title: Enzymatic activities of mouse vas deferens protein : reduction of aldehydes and steroidal compounds
Degree: M.Sc.
Year: 1997
Subject: Mice -- Physiology
Vas deferens
Hong Kong Polytechnic University -- Dissertations
Department: Multi-disciplinary Studies
Pages: x, 64 leaves : ill. ; 30 cm
Language: English
InnoPac Record: http://library.polyu.edu.hk/record=b1421095
URI: http://theses.lib.polyu.edu.hk/handle/200/3575
Abstract: The objective of this project is to investigate if the mouse vas deferens protein (MVDP) primarily expressed in mouse vas deferens, catalyses the enzymatically the reduction of aldehyde and steroidal compounds. Since the physiological role of MVDP is not yet know, it is essential to find out the substrate specificity of this protein in order to elucidate its biological functions. In this investigation, gene encoding MVDP and human AR (Aldose reductase) cDNA have been cloned. MVDP gene was shown to encode a protein of 316 amino acids with 71% sequence homology with human AR. Recently, a bovine testicular 20帢-hydroxysteroid dehydrogenase was found to be identical to bovine lens AR, it was also found that the structural organization of a rat 3帢-hydroxysteroid dehydrogenase was shown to be similar to AR except for the fusion of exon 7 and 8. MVDP gene, obtained by screening vas deferens total RNA using RT/PCR was cloned into an expression vector pQE 31. The target gene was expressed in E.coli cells and the gene product was compared with human AR enzymatic activities using the spectrophotometric detection method. Using methyglyoxal as a substrate, the recombinant protein was shown to exhibit an optimum pH at 5.5 and temperature at 40 C. A pl value of 6.52 was also recorded. Kinetic analysis have shown that both human AR and MVDP recombinant protein catalyse aliphatic and aromatic aldehydes, but hexoses such as D-galactose and D-glucose were not reduced by this enzyme. MVDP was shown to catalyse the conversion of 17帢-hydroxyprogesterone to 17,20帢-dihydroxyprogesterone and progesterone to 20帢-hydroxyprogesterone like both testicular and ovarian 20 帢-hydroxysteroid dehydrogenase. However, human AR was shown to contain enzymatic activity which can use 17帢-hydroxyprogesterone as a substrate but not progesterone.

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