Pectinesterases tomato, molecular weight

Pressey and Avants (80) separated, by DEAE Sephadex A-50 chromatography, four forms of tomato pectinesterase, with molecular weights 35,500, 27,000, 23,700, and 24,300. The number and relative amounts of these components varied considerably with ripeness and variety of tomato, and no single extract contained all four. The four forms diflFered in heat stability and response to pH and cation concentration. The fourth form, the major species in most tomato extracts, had properties similar to those of the enzyme described by Lee and Macmillan (75), whose molecular weight, however, was estimated on Sephadex G-75 as 27,500 (81),... 

Delincee and Radola100 used a commercial preparation, as well as fresh tomatoes, for the preparation, purification, and characterization of tomato pectinesterase. The tomatoes were pressed and then homogenized directly with ammonium sulfate at 70% saturation. The precipitate obtained was extracted with 0.3 M phosphate and repeatedly salted out with ammonium sulfate, and the product was separated on a column of Sephadex G-75. The pattern of separation was similar to that in preceding work.50,97 A detailed study of the size properties of pectinesterase was conducted by gel-filtration and sedimentation analysis.100 By column and thin-layer gel-filtration on Sephadex G-75, the approximate molecular weight of a number of preparations of tomato pectinesterase was determined, values of 24,000 and 27,000 being obtained. A possible interaction of the... 

Four forms of pectinesterase were found in different tomato varieties (Marion, Homestead, and Pixie)83 by separation on columns of DEAE-Sephadex A-50, using elution with 150 mM sodium chloride at pH 6.0. By gel filtration on columns of Sephadex G-100, the molecular weights of the individual forms were found to be 22,000-27,000, and 35,000. 

Macmillan and coworkers51 105 106 purified pectinesterase produced by Clostridium multifermentans by using practically all of the available methods and materials (calcium phosphate gel, DEAE-cellulose, DEAE-, QEAE-, CM-, and SE-Sephadex, Sephadexes G-75, G-100, G-150, and G-200, Sepharose 4B, and zonal centrifugation). However, they could not separate pectinesterase from exo-pectate lyase, and, hence, they postulated that either (a) a complex of the two enzymes having an apparent molecular weight of 400,000 exists, or (b) the two enzymes are identical in their molecular species. On the basis of the mode of action of this pectinesterase in comparison with that of those from tomatoes and from Fusarium ox-ysporum, the existence of a complex of pectinesterase and exopectate lyase in Clostridium multifermentans appears to be the more probable. 

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