A novel subclassification for Kunitz proteinase inhibitors from leguminous seeds

Kunitz-type trypsin inhibitors from legume seeds have been characterized structurally. The presence of Cys-Cys in single or double chains shows a new pattern of proteins structurally not so closely related to STI. Therefore, briefly, with regard to cysteine content, plant Kunitz proteinase inhibitors may be classifed into four groups: no Cys-Cys at all, one, two and more than two Cys residues. Functional properties and diversity of these proteins are also briefly discussed.