Pectin lyases

Pectin lyases used in food processing have been reviewed.  

Pectin lyases are among the pectolytic enzymes found in various species of Basidiomycetes.  

Pectin lyase has been obtained from culture fluids of Alternaria solani (see also p. 381). 

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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... 

Bussink et al. [4] and Kusters-van Someren et al. [5] have shown that in A. niger for both polygalacturonases (PGs) and pectin lyases (PLs) families of genes are present seven... 

Structural analysis of the two pectate lyases PelC and PelE (5, 6), demonstrated that these proteins fold in a large heHx of parallel P strands. A stack of asparagine residues parallel to the helix probably plays a role in the stabUity of this structure. Identification of the structurally conserved amino adds lead to a reaHgnment of the protein sequences (7). In addition to Erwinia extracellular pectate lyases, the multiple aHgnment indudes the Bacillus subtilis pectate lyase, Aspergillus tdger and E. carotovora pectin lyases and plant proteins. 

As already mentioned before a complete family of pectin lyases is present in A. niger. With all the genes sequenced and individually expressed, sometimes via promoter gene fusions (see below), the way is open to characterize the full spectrum of activities as outlined in the intro-... 

Fig. 1. Schematic overview of Aspergillus niger pectin lyase genes pel A to pelF aa, amino acid m.p. mature protein.

Table 2. Compilation of features and properties of Aspergillus niger pectin lyase genes and enzymes. WT, wild type n.d., not determined.

Expression of pectin lyase genes and localization of corresponding enzymes... 

As already mentioned in the previous section thus far we have not been able to demonstrate any pectin lyase activity for PLC and PLE. We believe that this is not a result of PLC and PLE not being real pectin lyases but rather our failure to identify the right substrate(s) or... 

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. 

Sherwood, R.T. 1965 Pectin lyase and polygalacturonase production by Rhizoclonia solani and other fungi. Phytopathology. 56 279-286. 

Pectin lyase and pectate lyase activities were assayed by measuring the increasing of the absorbancy at 235 nm by the method of Albersheim and Killias (12, 13) when pectin or sodium pectate was used as the substrate, repectively. 

The catalytic capacity of several excreting pectolytic enzymes obtained from various yeast strains was examined using in vivo and biochemical techniques. Of the 33 yeast strains studied 30 were isolated from champagne wine during alcoholic fermentation. Only one yeast strain was found to excrete pectolytic enzymes and was identified as Saccharomyces cerevisiae designated SCPP. Three types of pectolytic enzymes were found to be excreted by SCPP polygalacturonase (PG), pectin-lyase (PL) and pectin-esterase (PE) [1]. 

Pectin lyase from Fusarium oxysporum f. sp. radicis lycopersici purification and characterization... 

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