| 摘要 |
PURPOSE:To contrive to improve the yield of pectic acid lyase by culturing in a medium a transformed bacterium prepared by transforming a bacterium with a recombined plasmid containing a protein which is a pectinic acid lyase III gene. CONSTITUTION:A DNA molecule or a derivative thereof (e.g. plasmid pNN3) coding a region relating to the expression and excretion of a protein (the pectinic acid lyase II gene of an Erwinia bacterium) containing a DNA sequence of the formula is inserted into an Escherichia coli HB101 strain to give a transformed Escherichia coli strain HB101/pNN3 (A). The strain A is cultured in a medium containing casamino acid, etc., to give a cultured product (B). The component B is purified by an ion exchange method, etc., to provide the pectinic acid lyase III having the following properties; action: reacts with polygaractoronide to produce an unsaturated galacturonide; substrate specificity: acts with pectin; the optimal pH: 6-11; the optimal temperature: 60 deg.C; is activated with Ca ions and is inhibited with EDTA; mol.wt.: approximately 36000 (SDS polyacrylamide gel electrophoresis method), etc. |
