Kinetic Modulation of Fungal Amylase in The Presence of Divalent Ions
Amylase is a metalloprotein and requires metal ions for the activity, structural integrity and thermal stability. The amylase is extracted and purified from fungal species isolated from soil with ammonium salt precipitation, dialysis and DEAE ion exchange chromatography and the kinetics of divalent ion modulation of fungal amylase have been investigated in the present study. Kinetic studies revealed that at pH 4.5 and 9.5, 5mM Ca2+ induced V-type activation of amylase catalyzed starch hydrolysis. Similarly, at pH 7.5, V-type activation of amylase is observed in the presence of 7mM Fe2+. Amylase is inhibited un-competitively at 10mM Cu2+ at pH 4.5 and 7.5, which is changed to competitive inhibition at pH 9.5. However, the competitive inhibition of amylase catalyzed starch hydrolysis is observed in 10mM Hg2+ at pH 4.5 and 7.5. These findings suggest that divalent ion modulation of fungal amylase is pH dependent.
Index Terms- Amylase, activators, divalent ions, inhibitors, kinetics