Inhibition of xyloglucanase from an alkalothermophilic Thermomonospora sp. by a peptidic aspartic protease inhibitor from Penicillium sp. VM24

• Published in: Bioresource technology 2012-11, Vol.123, p.390-399
• Main Authors: Menon, Vishnu, Rao, Mala
• Format: Article
• Language: English
• Subjects: Actinomycetales - enzymology; Alkalies; Aspartic Acid Proteases - antagonists & inhibitors; Aspartic Acid Proteases - metabolism; Aspartic protease; Aspergillus; Aspergillus - enzymology; Bifunctional inhibitor; Biocontrol agent; Circular Dichroism; Denaturation; Enzymes; Fusarium - drug effects; Glycoside Hydrolases - antagonists & inhibitors; Glycoside Hydrolases - metabolism; Inactivation mechanism; Inhibition; Inhibitors; Kinetics; Least-Squares Analysis; Microbial Sensitivity Tests; Mycelium - drug effects; Mycelium - growth & development; o-Phthalaldehyde - metabolism; Penicillium; Penicillium - chemistry; Peptides - pharmacology; Protease Inhibitors - pharmacology; Rhizopus - drug effects; Spectrometry, Fluorescence; Steady state; Substrate Specificity - drug effects; Temperature; Time Factors; Xyloglucanase
• ISSN: 0960-8524; 1873-2976
• DOI: 10.1016/j.biortech.2012.07.050

► A bifunctional inhibitor against xyloglucanase and aspartic protease has been isolated. ► Kinetic interactions of xyloglucanase and inhibitor revealed non-competitive inhibition. ► Inactivation of xyloglucanase is due to the irreversible denaturation of the enzyme. ► The inhibitor is potential as a biocontrol agent for plant protection against phytopathogenic fungi. A bifunctional inhibitor from Penicillium sp VM24 causing inactivation of xyloglucanase from Thermomonospora sp and an aspartic protease from Aspergillus saitoi was identified. Steady state kinetics studies of xyloglucanase and the inhibitor revealed an irreversible, non-competitive, two-step inhibition mechanism with IC50 and Ki values of 780 and 500nM respectively. The interaction of o-phthalaldehyde (OPTA)-labeled xyloglucanase with the inhibitor revealed that the inhibitor binds to the active site of the enzyme. Far- and near-UV spectrophotometric analysis suggests that the conformational changes induced in xyloglucanase by the inhibitor may be due to irreversible denaturation of enzyme. The bifunctional inhibitor may have potential as a biocontrol agent for the protection of plants against phytopathogenic fungi.