A thermostable chitinase with chitin-binding activity from Phaseolus limensis.

Area of Science:

• Biochemistry
• Plant Science
• Enzymology

Background:

• Chitinases are enzymes crucial for chitin degradation.
• Plant-derived chitinases are investigated for agricultural and biotechnological applications.
• Lima beans (Phaseolus limensis) are a potential source of novel enzymes.

Purpose of the Study:

• To isolate and characterize a chitinase enzyme from large lima bean seeds.
• To evaluate the enzyme's chitin-binding activity and biochemical properties.
• To assess the antifungal potential of the purified chitinase against plant pathogenic fungi.

Main Methods:

• Enzyme extraction and purification using ammonium sulfate precipitation, affinity chromatography (Affi-gel blue gel), and HPLC (SP-Toyopearl).
• Isoelectric focusing electrophoresis to determine the isoelectric point (pI).
• Enzyme activity assays at varying pH and temperature conditions; stability tests.

Main Results:

• A 28.6-kDa chitinase with chitin-binding activity was successfully purified.
• A 108-fold increase in specific activity was achieved compared to the crude extract.
• The purified chitinase showed an optimal pH of 5.4, optimal temperature of 40-50°C, and stability up to 55°C.
• The enzyme exhibited potent inhibitory effects against fungal species like Fusarium solani, Pythium aphanidermnatum, and Sclerotium rolfsii.

Conclusions:

• Large lima beans harbor a chitinase with significant chitin-binding and antifungal properties.
• The purified enzyme demonstrates potential as a biocontrol agent against fungal plant diseases.
• Further research into this chitinase could lead to novel agricultural applications.