Structure of a sugar chain of a protease inhibitor isolated from barbados pride (Caesalpinia pulcherrima Sw.) seeds.

An asparagine-linked sugar chain of a protease inhibitor from barbados pride (Caesalpinia pulcherrima Sw.) was liberated by hydrazinolysis. After N-acetylation, the reducing end residue of this carbohydrate unit was coupled with 2-aminopyridine and the pyridylamino (PA-) derivative was purified by gel-filtration and reversed-phase HPLC. The structure of the resulting PA-sugar chain was determined mainly by stepwise exoglycosidase digestions and 500 MHz 1H-NMR spectroscopy and proved to be as follows: (formula; see text).