Catalase Activity in Tomato Fruits at Different Stages of Their Development

Abstract

Ever since its discovery by LOEW catalase has been the cause of much speculation and investigation. During the thirty-years since its discovery several hundred papers have been written concerning it, and we are still wondering whether its sole function is that of breaking down hydrogen peroxide into water and oxygen, or whether it has other yet unknown funetions to perform. Because of the already profuse literature on the subject the briefest possible statements concerning the experiments performed will be given in this paper. Readers interested in the literature are referred to the paper by BATTELLI and STERN (2) in 1910 and one by MORGULIS (5) in 1924. Each of these has a very extensive bibliography.For several years the senior author has been investigating the growth and respiration (3, 4) of tomato fruits. In this connection it was thought profitable also to make some catalase determinations on similar fruits, and find out whether there was any correlation between growth, respiration and catalase activity. Hence the catalase determinations here recorded.The method of determining the catalase activity was the same as that employed by APPLEMAN (1). Fruits were sliced and placed in a saturated solution of CaCO, and left there a few minutes, and then ground in a food chopper. The juice was filtered through glass wool to free it from the pulp. One cc. of this juice was placed in a bottle (the reaction chamber) and one cc. of distilled water was added to this. The reaction chamber as well as the bottles containing the juice and the container of H202 were kept at 20°C. in a constant temperature bath, which did not vary more than half a degree either way. When the apparatus had been adjusted, 5 cc. of neutral H202 was added to the reaction chamber, which was then constantly shaken by hand. Readings of the oxygen liberated were taken every minute for five minutes. The total amount of oxygen liberated for the five minutes is used in calculations throughout this report. There was of course the usual dropping off of oxygen liberation as time went on.The fruits used for these experiments were for the most part grown in the greenhouse, though a few were grown out-doors. The experiments were conducted at four different times by three different individuals, who beforehand were not familiar with the results obtained by the others. Thus the Paper from the Department of Botany of the University of Michigan, no. 342.