Characterization and mode of action of an exopolygalacturonase from the hyperthermophilic bacterium Thermotoga maritima.

An intracellular pectinolytic enzyme, PelB (TM0437), from the hyperthermophilic bacterium Thermotoga maritima was functionally produced in Escherichia coli and purified to homogeneity. PelB belongs to family 28 of the glycoside hydrolases, consisting of pectin-hydrolysing enzymes. As one of the few bacterial exopolygalacturonases, it is able to remove monogalacturonate units from the nonreducing end of polygalacturonate.

Partially esterified oligogalacturonides are the preferred substrates for pectin methylesterase of Aspergillus niger.

Investigations on the mode of action of Aspergillus niger pectin methylesterase (PME) towards differently C(6)- and C(1)-substituted oligogalacturonides (oligoGal p A) are described. De-esterification of methyl-esterified (un)saturated oligoGal p A proceeds via a specific pattern, depending on the degree of polymerization. Initially, a first methyl ester of the oligomer is hydrolysed, resulting in one free carboxyl group.

Molecular and biochemical characterization of the thermoactive family 1 pectate lyase from the hyperthermophilic bacterium Thermotoga maritima.

The ability of the hyperthermophilic bacterium Thermotoga maritima to grow on pectin as a sole carbon source coincides with the secretion of a pectate lyase A (PelA) in the extracellular medium. The pel A gene of T. maritima was functionally expressed in Escherichia coli as the first heterologously produced thermophilic pectinase, and purified to homogeneity.

Altered cell wall disassembly during ripening of Cnr tomato fruit: implications for cell adhesion and fruit softening.

The Cnr ( C olourless n on- r ipening) tomato ( Lycopersicon esculentum Mill.) mutant has an aberrant fruit-ripening phenotype in which fruit do not soften and have reduced cell adhesion between pericarp cells. Cell walls from Cnr fruit were analysed in order to assess the possible contribution of pectic polysaccharides to the non-softening and altered cell adhesion phenotype.

Mode of action of pectin lyase A of Aspergillus niger on differently C(6)-substituted oligogalacturonides.

A thorough investigation of the mode of action of Aspergillus niger (4M-147) pectin lyase A (PLA) on differently C(6)-substituted oligogalacturonides is described. PLA appeared to be very specific for fully methyl-esterified oligogalacturonides: removal of the methyl-ester or changing the type of ester (ethyl esterification) or transamidation resulted in (almost) complete loss of conversion. The PLA activity increased with increasing length of the substrate up to a degree of polymerization (DP) of 8 indicating the presence of at least eight subsites on the enzyme.