Characterization of aldolase from Methanococcus jannaschii by gas chromatography

Abstract

The products of reactions catalyzed by Methanococcus. jannaschii (Mj) aldolase using various substrates were identified by gas chromatography (GC). Although Mj aldolase is considered a fuculose-1-phosphate aldolase based on homology searching after gene sequencing, it has not been proven to be a fuculose-1-phosphate aldolase based on its reaction products. Mj aldolase was found to catalyze reactions between glycoaldehyde or D, L-glyceraldehyde and DHAP (dihydroxyacetone phosphate). Before performing GC the ketoses produced were converted into peracetylated alditol derivatives by sequential reactions, i.e., dephosphorylation, NaBH4 reduction, and acetyllation. By comparing the GC data of final products with those of standard alditol samples, it was found that the enzymatic reactions with glycoaldehyde, D-glyceraldehyde, and D, L-glyceraidehyde produced D-ribulose-1-phosphate, Dpsicose-1-phosphate, and a mixture of D-psicose and Ltagatose-1-phosphate, respectively. These results provide direct evidence that Mj aldolase is a foculose-1-phosphatea1dolase.