| Summary: | 碩士 === 國立臺灣大學 === 農業化學系 === 81 === In this study, the extraction and purification of pectines-
terase (PE) from snap bean sprouts were investigated. The
PE activity in different parts of snap bean sprouts at
different stages of growth, as well as the changes in PE
isozymes during growth were also investigated by using CM-
Sepharose CL-6B cation exchange chromatography. The optimal
pH and NaCl concentration for the reaction of each PE
isozyme upon pectin of different DE's were further studied,
in order to understand the possible physiological role of the
PE isozymes. The results obtained were as follows: 1. By
homogenizing, filtering and washing the snap bean sprouts with
deionized water, which resulted in removable of water-solu- ble
proteins, and subsequent extraction of PE with 1M NaCl solu-
tion, a 26 fold purification of the PE, as compared with
direct extraction of PE with 1 M NaCl solution, was achieved.
The crude PE enzyme extract was then subjected to ammonium
sulfate preci- pitation, by collecting the precipitate at
0-100% saturation,and further to CM-Sepharose CL-6B cation
exchange chromatography, which resulted in successful
separation off our PE isozymes, which were assigned as PE1,
PE2, PE3 and PE4 according to the order of elution by salt-
concentration gradient.The purification folds of the PE
isozymes ranged from 60 to 120, with anaverage of 70 folds,
while the yields ranged from 4.6 to 42.9 %, with a totol yield
of 70.4%. 2. At the first day of incubation of the snap
bean sprouts, total PE activity decreased to one half, and then
increased with the growth of the sprouts,but the rate of
increase was different in different parts of the sprouts.The
total PE activity in roots increased at the highest rate,
resulting in different specific PE activities in the order of:
root> stem> leaf>> cotyledon.
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