PEROXIDASE FROM STRAWBERRY FRUIT (FRAGARIA ANANASSA DUCH) - PARTIAL PURIFICATION AND DETERMINATION OF SOME PROPERTIES

摘要

In this work, peroxidase from strawberry fruit was detected, partially purified, and characterized. The total enzyme extract (both soluble and associated to membranes) was partially purified by means of (NH4)(2)SO4 precipitation, molecular exclusion chromatography, and cationic exchange chromatography. The purification grade achieved was near 35. Effects of temperature and pH, stability against pH, and thermal stability were analyzed on both crude and partially purified extracts. The maximum enzyme activity was observed at 30 degrees C and pH 6.0. The enzyme showed low thermal stability and maintained activities equal to or greater than 50% of its maximum value in the 4-11 pH range. Two peroxidase isoenzymes were detected in strawberry fruit; they were of the basic type (isoelectric points 9.5-10.0) and had molecular masses of 58.1 and 65.5 kDa. Strawberry fruit peroxidase activity decreased remarkably as the fruit ripened and was found primarily in a membrane-bound form. Maximum specific activities were found at the ''small green'' and ''large green'' ripening stages.