Aldolases reversibly catalyze the cleavage of carbon-carbon bonds. A recombinantsnailsialicacidaldolase (sNPL) differs significantly in its carbohydrate substrate promiscuity from other sialicaldolases described so far. In addition, sNPL was able to synthesize a series of 4-hydroxy-2-oxoates using the corresponding aliphaticaldehyde substrates.