Hidetaro Takehana

Immunological properties of β-fructofuranosidase from ripening tomato fruit

Abstract The amount of tomato fruit β-fructofuranosidase extractable from the cell walls during ripening parallelled the changes in activity of the enzyme. Using the techniques of radioimmunoassay, double immunodiffusion analysis and immunotitration, no differences in immunological properties of β-fructofuranosidase between the various stages of fruit ripening were detected.

Cell Wall-bound Enzyme Properties of β-Fructofuranosidase Bound to Tomato Cell Wall

Tomato cell wall fraction washed three times with water was used as a preparation of insoluble β-fructofuranosidase (β-FFase). The insoluble β-FFase could not be released from cell wall fraction in the presence of substrate.Comparative studies on kinetics of soluble and insoluble forms of β-FFase were performed.There were no marked differences between the two forms with regard to pH dependency, Michaelis constant and some inhibitors.Considerable difference was observed between the two forms in both temperature sensitivity and dependency. The soluble form was no longer active at 55°C, but the insoluble form still retained 65% of the maximum activity at this temperature. There was a marked break in the Arrhenius plot at 19°C with the insoluble form, but a linear line was obtained at a temperature range of 10°C to 30°C with the soluble form. Activation energies were 10,800 and 17,300 cal/mole in the lower temperature range (below 19°C) for the insoluble and the soluble form, respectively. But they differed w...

Studies on the Pectolytic Enzyme: Part IV Purification of Tomato Fruit PectinesterasePart V. Some Properties of the Purified Tomato Pectinesterase

Pectinesterase was extracted from the pulp of tomato fruit (Lycopersicum esculentum var. Hikari) pericarp with 250 mM potassium phosphate buffer, pH 8.0, and purified about 60 folds by means of ammonium sulfate fractionation, chromatography on DEAE-cellulose and gel filtration on Sephadex G-100 column. The enzyme preparation thus obtained was confirmed to be homogeneous state both ultracentrifugationally and disk electrophoretically. The sedimentation coefficient of this enzyme was calculated to be 3.17 S.

Studies on Pectic Enzymes

1. Alkali titration method is inquired and employed in the determination of the pectin-es-terase activity. 2. The PE is extracted from tomato pulp by Na2HPO4 at pH 8. It is more influenced by pH than extractant. 3. The PE is precipitated by (NH4)2SO4 at 11_??_70% saturated. The precipitated enzyme is stable at dry state. 4. Pectin solutin is decomposed by PE and produces acid, but this reaction is inhibited at pH 3.8. 5. The PE has opt. pH 6_??_7.5, and decomposes over 80% methoxyl groups in pectin. 6. The opt. temp. is 60°, and loses the activity at 80° 7. CaCl2 and (NH4)2SO4 accelerate the PE activity. 8. The enzyme does not decrasc the viscosity of pectin or pectic acid solution, and does not produce the reducing sugar. 9. The characters of the PE from tomato differs from the PE in mould or bacteria.