Traditionally, UV absorption detection (A,,,) of 4,5-unsaturated bonds has been used to evaluate the depolymerization of pectic polysaccharides by pectate lyase (PLI. This approach ignores the generation of oligogalacturonic acids without a 4,5unsaturated function that appear early in the time course of PL cleavage. We found that high-performance anion-exchange chromatography and pulsed amperometric detection (HPAEC-PAD) could separate and detect oligogalacturonic acids both with and without 4,5-unsaturated functions at their nonreducing ends in PL digests of polygalacturonic acid (PGA) and tobacco cell walls. The "re~mbin~t" PL used was free of endo~~galac~ronase activity. Peaks were identified in PL digest chromato~ams by retention time agreement with oligogalacturonic acid standards purified by preparative high-buoyance liquid chromatography and a PGA autoclave bydrolysate that contained oligogalacturonic acids up to degree of polymerization (dp) 40, which lacked the 4,5unsaturated function. When comparing like dp oligogalacturonic acids, those without the 4,Sunsaturated function eluted earlier from the HPAEC CarboPac PA1 column than did their unsaturated counterparts. These techniques provide the first means for the dp assignment of oligogalacturonic acids generated by both hydrolytic and lytic cleavage of polygalacturonic acid and plant cell walls.