The first mammalian aldehyde oxidase crystal structure: insights into substrate specificity

Area of Science:

• Biochemistry
• Structural Biology
• Pharmacology

Background:

• Aldehyde oxidases (AOXs) are critical molybdenum-containing enzymes involved in drug metabolism.
• Aldehyde oxidase 3 (AOX3) is a major drug-metabolizing enzyme in rodents, highlighting its pharmacological relevance.
• Understanding AOX structure is crucial for drug design and mechanistic studies, yet mammalian AOX structures were previously unknown.

Purpose of the Study:

• To determine the crystal structure of mouse liver aldehyde oxidase 3 (AOX3).
• To elucidate the enzymatic characteristics and substrate specificity of AOX3.
• To provide insights into the catalytic differences between AOX and xanthine oxidoreductase.

Main Methods:

• Crystallization and X-ray diffraction to solve the 3D structure of mouse AOX3 to 2.9 Å resolution.
• Kinetic studies and mutagenesis experiments to investigate enzyme activity.
• Molecular docking and molecular dynamics simulations to understand substrate interactions.

Main Results:

• The first crystal structure of a mammalian aldehyde oxidase (mouse AOX3) has been successfully determined.
• The structure reveals key features of the protein active center, including the molybdenum cofactor.
• Combined structural, kinetic, and computational data provide a molecular basis for AOX3's broad substrate specificity.

Conclusions:

• The solved structure of mouse AOX3 is a significant advancement for drug design and understanding enzyme mechanisms.
• Comparisons with xanthine oxidase structures explain differences in substrate and inhibitor specificities.
• This work provides crucial molecular insights into the function and specificity of aldehyde oxidases.