Copper-Dependent Polysaccharide Monooxygenases: Mechanism and Function

Area of Science:

• Biochemistry
• Enzymology
• Carbohydrate Chemistry

Background:

• Polysaccharide monooxygenases (PMOs) are enzymes crucial for degrading carbohydrate polymers.
• They perform hydroxylation of glycosidic bonds at a mononuclear copper active site.
• PMOs utilize either molecular oxygen (O2) or hydrogen peroxide (H2O2) as cosubstrates.

Purpose of the Study:

• To review the diverse catalytic mechanisms of PMOs.
• To discuss the roles of O2 and H2O2 in PMO-mediated polysaccharide degradation.
• To summarize advancements in understanding O2 activation by PMOs.

Main Methods:

• Review of existing literature on PMO mechanisms.
• Analysis of catalytic chemistry including monooxygenase, oxidase, and peroxygenase activities.
• Discussion of key discoveries and unresolved questions in PMO function.

Main Results:

• PMOs exhibit three distinct catalytic chemistries: monooxygenase, oxidase, and peroxygenase.
• Understanding of PMO mechanism and function has advanced significantly.
• Key questions persist regarding the precise utilization of O2 and H2O2.

Conclusions:

• PMOs are versatile enzymes with complex catalytic mechanisms involving copper centers.
• Further research is needed to fully elucidate O2 activation and cosubstrate utilization in polysaccharide hydroxylation.
• This review consolidates current knowledge and identifies future research directions for PMOs.