Quantitative comparison of protease inhibitors in seeds from various geographical and phylogenetic classifications

Plants have been shown you years to be a good source of protease inhibitors. There has not however been a comparative study to show relative levels of inhibitor between different species. In the following study, representative seeds (38) from four members of the plant family were compared in terms of their trypsin and elastase inhibitor content. Purified bovine pancreatic trypsin and rat pancreatic elastase were used as the source of enzyme for inhibition. Seeds from the family Fabacclae/Leguminosae contained significantly higher levels of inhibitors that the other families investigated. Three beans, the marama bean, Hopi-red lima and the lab-lab contained more than a three fold higher concentration of trypsin inhibitor than most other beans. The marama bean had an extremely high content of elastase inhibitor, more than 10 times the level found in other seeds. It was observed that different species within the same genus contained comparable levels of inhibitors and with some exceptions, the content of both inhibitors was equivalent within a single species. There appeared to be no definitive geographical location or climatic conditions that defined protease inhibitor levels. The marama bean would appear to be a good candidate for increasing protease inhibitor levels as a protective mechanism in seeds low in inhibitor content through molecular biological approaches.