Effects of NaCl and pH on the structural conformations of kidney bean vicilin

► Purified red kidney bean vicilin was composed of two polypeptides of 43 and 45 kDa. ► Tryptophan fluorescence was higher at pH 3.0 and 5.0 than at 7.0 and 9.0 (NaCl = 0 M). ► Addition of NaCl led to enhanced tryptophan fluorescence at all pH values studied. ► Tyrosine fluorescence was suppressed indicating close proximity to hydrophilic groups. ► Changes in secondary and tertiary conformations were dependent on NaCl concentration.