Chapter 36 - Proteinase Inhibitors From Buckwheat (Fagopyrum esculentum Moench) Seeds

Abstract

Proteinase inhibitors in buckwheat seeds (BWI) consist of two main groups – endogenous involved in the regulation of storage protein metabolism and a group of exogenous proteinase inhibitors capable of suppressing the growth and development of pathogenic microorganisms. Exogenous protease inhibitors are presented by two subgroups, i.e., anionic and cationic inhibitors. As consisted with their amino acid sequences, all anionic inhibitors, as well as two of the cationic inhibitors (BWI-3c and BWI-4c), were shown to belong to the potato proteinase inhibitor 1 family. The 3D structure of the proteinase inhibitor BWI-2c determined by NMR spectroscopy and revealing two antiparallel α-helices stapled by disulfide bonds showed that BWI-2c represents a new family of proteinase inhibitors termed α-hairpinin with an unusual α-helical hairpin fold. Possibility of obtaining transgenic tobacco and potato plants resistant to bacterial infections and insects by introduction of the gene of serine proteinase inhibitor BWI-1a (ISP) from buckwheat seeds has been demonstrated. Stable retention and expression of the heterologous protective ISP gene has been demonstrated on a collection of individual transgenic tobacco lines maintained in aseptic culture for more than 10 years.