Effect of ionizing radiation on structural and functional attributes of red kidney bean (Phaseolus vulgaris L.) lectin

- Structural stability of pure PHA towards gamma radiation is moisture dependent.
- Gamma radiation inactivates purified PHA in dry and 50% moisture condition at 30 kGy.
- Irradiation of PHA solution destroyed the structure completely at dose ≥10 kGy.
- 50% loss in hemagglutination activity was observed at dose of 50 kGy in kidney bean seeds.

Gamma radiation inactivation of phytohemagglutinin (PHA) of red kidney bean in purified form as well as in seeds in different moisture conditions was demonstrated at different doses viz. 1, 10, 30, 50, 100 and 200 kGy. Irradiation of PHA in dry state (99.5% dry) or in 50% moisture condition showed structural intactness as studied by SDS-PAGE, size exclusion chromatography (SEC), fluorescence measurement, CD spectroscopy below 30 kGy, while a 50% reduction in hemagglutinin and mitogenic activity was observed in the dose range of 30-50 kGy. Radiation inactivation of purified PHA was more pronounced when irradiated in aqueous solution form resulting in complete destruction of secondary and tertiary structure as well as function at a dose of 10 kGy. Radiation processing of dry and soaked seeds of kidney bean exhibited 50% loss in functional activity of PHA at the doses of 50 and 30 kGy, respectively. Practicality of implication of the radiation processing for inactivation of this antinutrient in legume seeds is discussed.