ARS | Publication request: Digestion patterns of two commercial endopolygalacturonases on polygalacturonate oligomers with a degree of polymerization from 7

Submitted to: Florida State Horticultural Society Meeting
Publication Type: Abstract Only
Publication Acceptance Date: April 10, 2009
Publication Date: April 14, 2009
Citation: Cameron, R.G., Goodner, K., Luzio, G.A., Savary, B.J. 2009. Digestion patterns of two commercial endopolygalacturonases on polygalacturonate oligomers with a degree of polymerization from 7–21. Florida State Horticultural Society Meeting. Paper No. HP1.

Technical Abstract: Many fruits and fruit juices are enzymatically treated to aid the process of liquefaction, juice extraction, viscosity reduction and juice clarification. Polygalacturonases are a major component of enzyme mixtures used for these purposes. Endopolygalacturonases (EPG) fragment the pectin homogalacturonan chain, cutting the molecule within a contiguous stretch of demethylated galacturonic acid (GA) residues. To increase our understanding of this process, GA oligomers with a degree of polymerization (DP) ranging from 7 – 21 were digested with two commercial endopolygalacturonases (EPG M1 and EPG M2). Peptide mass fingerprinting with MALDI-TOF MS suggested identity of the EPGs as EPG II from Aspergillus niger (EPG M1) and endo-PG I from A. aculeatus (EPG M2). Aliquots were collected at various time points during the digestion and the resulting fragmentation patterns were determined. Individual oligomer masses were estimated and converted to molar concentrations. The distribution of cleavage products produced by the EPGs differed. Smaller fragments, especially GA monomer, were produced earlier with EPG M1. Rate constants for each of 81 possible reactions were estimated by computer simulation. When compared to optimized data for individual reactions, the experimental data provided a good fit, thus indicating the model is a good approximation of the fragmentation process.