ISSN:
1399-3054
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Biology
Notes:
Pectins from persimmon (Diospyros kaki L.) fruit pericarp were sequentially extracted with 0. 05 M trans-1,2-diaminocyclohexane-N,N, N′, N′-tetraacetic acid (CDTA), 0. 05 M Na2CO3 (1°C) and Na2CO3 (20°C) and the carbohydrate composition and metabolism during development determined. Young persimmon fruits contained a large proportion of pectins, 46% by dry weight, that decreased to 20% with ripening. This decrease occurred in the CDTA and Na2CO3 (1°C) fractions, mainly composed of uronic acids, and represents a net loss of uronic acids, arabinose and galactose. The amount of non-cellulosic neutral sugars was especially high in the Na2CO3 (20°C) fraction. The loss of pectins was also accompanied by a depolymerisation of the polysaccharides extracted in the three pectic fractions. However, none of these changes can be attributed to the action of polygalacturonase activity. Proteins were extracted from the pericarp tissue, but endopolygalacturonase (EC 3. 2. 1. 15) activity, determined as a decrease in viscosity of polygalacturonic acid, was not observed in the extract. Determination of exopolygalacturonase (EC 3. 2. 1. 67) activity by measuring the release of reducing groups from polygalacturonic acid was also negative. The results presented indicate that polygalacturonase is not responsible for the metabolism of pectins during persimmon fruit ripening.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1399-3054.1993.tb00168.x
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