Endopolygalacturonase

Immobilization. The fixing property of PEIs has previously been discussed. Another appHcation of this property is enzyme immobilization (419). Enzymes can be bound by reactive compounds, eg, isothiocyanate (420) to the PEI skeleton, or immobilized on soHd supports, eg, cotton by adhesion with the aid of PEIs. In every case, fixing considerably simplifies the performance of enzyme-catalyzed reactions, thus faciHtating preparative work. This technique has been appHed to glutaraldehyde-sensitive enzymes (421), a-glucose transferase (422), and pectin lyase, pectin esterase, and endopolygalacturonase (423). 

Other polysaccharides of primary cell walls.-A complex mixture of enzymes including endopolygalacturonase, pectin methylesterase, and/or pectin lyase solubilizes a mixture of polysaccharides from the primary cell walls of fruits [57-64]. Food scientists have referred for some 15 years to this mixture of polysaccharides as the hairy region to describe the highly branched character of the polysaccharides in the fraction and to emphasize the contrast to unbranched homogalacturonan. The recent discovery of rhamnogalacturonan hydrolase [65,66], which selectively cleaves the backbone of RG-I, led to the realization that the hairy... 

Partial characterization of xylogalacturonans from cell walls of ripe watermelon fruit inhibition of endopolygalacturonase activity by xylosylation... 

Pectic polysaccharides were released from total walls by digestion with endopolygalacturonase... 

English, P.D., Maglothin, A., Keegstra, K., and Albersheim, P. (1972) A ceU wall-degrading endopolygalacturonase secreted by Colletotrichum lindemuthianum. Plant Physiol. 49 293-297. 

Figure 6. Hypothetical action pattern of neutral and alkaline PME isofomis. methylated gtdacturonic units O unesterified galacturonic acids EPG, endopolygalacturonase.

The most conspicuous concentrations of calciiun in the cell-walls of the flax hypocotyl were in the epidermal and subepidermal layers, especially at the tricellular junctions (figure 13 D), where these were filled with pectic polymers [67], Open tricellular jimctions with intercellular spaces had smaller areas of calcium accumulation where the walls of each pair of cells diverged. These sites were occupied by relatively linear pectic polymers with a low degree of esterification, which could be visualised with gold-kbeUed endopolygalacturonase [68] and were extractable by chelation of calcium with CDTA. Similar pectic polymers are located in the corresponding sites in other plant tissue, as established by susceptibility to polygalacturonase... 

A single mutation affects enzyme activity but not elicitorand PGIP binding abilities of endopolygalacturonase... 

Figure 4. Inhibition of A. nigerand F. moniliforme endopolygalacturonase by PGIP purified fom tomato transgenic plants (A) and from bean (B).

The mode of action and substrate specificity of all pectin lyases together with the endopolygalacturonases is currently one of the main topics of our research. 

As shown for the pectin lyases endopolygalacturonases are also present as a gene family in A. niger. The individual endopolygalacturonases are also characterized both at the genetic and biochemical level. 

One potential N-glycosylation site is present in all endopolygalacturonases. This N-glycosylation sequon is conserved throughout whereas PGI has two sequons, the second one at a more C-terminal location. 

MOLECULAR CHARACTERIZATION AND EXPRESSION OF COLLETOTRICHUM LINDEMUTHIANUM GENES ENCODING ENDOPOLYGALACTURONASE... 

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