Synthesis of oligogalacturonates conjugated to BSA.

The synthesis of three oligogalacturonates with an aldehyde spacer attached at the reducing end is described. Trigalacturonates alpha-d-GalpA-(1-->4)-alpha-d-GalpA-(1-->4)-alpha-d-GalpA-(1-->O(CH(2))(7)CHO and alpha-d-GalpA(Me)-(1-->4)-alpha-d-GalpA(Me)-(1-->4)-alpha-d-GalpA(Me)-(1-->O(CH(2))(7)CHO as well as hexagalacturonate alpha-d-GalpA-(1-->4)-[alpha-d-GalpA-(1-->4)](4)-alpha-d-GalpA-(1-->O(CH(2))(7)CHO are prepared by stepwise coupling of galactose units followed by oxidation of the 6-positions. The alpha-linkages are formed by employing n-pentenyl galactosides as glycosyl donors and N-iodosuccinimide/triethylsilyl triflate as the promoter. Deprotection furnishes the three target oligogalacturonates, which are subsequently linked to bovine serum albumin by reductive amination. These neoglycoproteins will serve as immunogens for generation of new antibodies that can be used for localization and characterization of pectin in plants.