ISSN:
1399-3054
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Biology
Notes:
Extracellular acidic isoperoxidases (EC 1.11.1.7), isolated from both the cell walls and intercellular spaces of lupin (Lupinus albus L. cv. multolupa) hypocotyls, bound to water-insoluble pectins of wall fragments also isolated from the hypocotyls. The binding was sáturable by increasing the isoenzyme concentration in the assay medium and it was dependent on the pH; neutral pH (6.0–7.0) favoured release, while acidic pH (4.0–5.0) favoured the attachment to the cell wall. Binding of acidic isoperoxidases to wall fractions was correlated with the in vitro acid-induced growth of hypocotyl segments, and both were modulated in the same direction by the Ca2+/H+ ratio in the incubation media, although the two responses were clearly separated when the Ca2+/H+ ratio varied. Binding of acidic isoperoxidases of cell walls could operate as a fine control of the activity of these cell wall enzymes, although its physiological role in the cell wall stiffening remains unclear. Some aspects of Ca2+ on the control of peroxidase activity at this level are also discussed.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1399-3054.1988.tb00592.x
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