Pasteurella multocida sialic acid aldolase: a promising biocatalyst

Area of Science:

• Biocatalysis
• Enzymology
• Synthetic Chemistry

Background:

• Sialic acid aldolases (NanAs) are enzymes that catalyze reversible reactions involving N-acetylneuraminic acid (Neu5Ac).
• Characterizing NanA activity is crucial for understanding their potential in synthesizing sialic acid derivatives.

Purpose of the Study:

• To develop a capillary electrophoresis assay for characterizing NanA activity.
• To compare the kinetic properties, pH profiles, and substrate specificities of NanAs from Pasteurella multocida (PmNanA) and Escherichia coli (EcNanA).
• To evaluate PmNanA as a superior catalyst for chemoenzymatic synthesis.

Main Methods:

• Development of a capillary electrophoresis assay for direct activity characterization.
• Determination of pH profiles and kinetic parameters for PmNanA and EcNanA.
• Substrate specificity studies using N-acetyl-D-mannosamine (ManNAc) derivatives.
• Enzyme expression level analysis.

Main Results:

• Both PmNanA and EcNanA exhibit activity across a broad pH range (6.0-9.0) with similar kinetic parameters.
• PmNanA efficiently synthesizes 8-O-methyl Neu5Ac using 5-O-methyl-ManNAc, unlike EcNanA.
• PmNanA demonstrates a 2.5-fold higher expression level compared to EcNanA.

Conclusions:

• PmNanA exhibits broader substrate tolerance and higher expression levels than EcNanA.
• PmNanA is a more effective biocatalyst for the chemoenzymatic synthesis of sialic acids and their derivatives.