Purification and N-terminal amino acid sequence of fructose-6-phosphate phosphoketolase from Bifidobacterium longum BB536

AIMS: The key enzyme in the fructose-6-phosphate shunt in bifidobacteria, Fructose-6-phosphate phosphoketolase (F6PPK; E.C. 4.1.2.22.), was purified to electrophoretic homogeneity for the first time from Bifidobacterium longum (BB536). METHODS AND RESULTS: A three-step procedure comprising acetone fractionation followed by fast protein liquid chromatography (FPLC) resulted in a 30-fold purification. The purified enzyme had a molecular mass of 300 +/- 5 kDa as determined by gel filtration. It is probably a tetramer containing two different subunits with molecular masses of 93 +/- 1 kDa and 59 +/- 0.5 kDa, as determined by SDS-PAGE. CONCLUSION: The deduced N-terminal amino acid sequences of the two subunits revealed no significant similarity between them and other proteins when compared to the data bases of EMBL and SWISS-PROT, indicating that this could be the first report on N-terminal amino acid sequence of F6PPK. SIGNIFICANCE AND IMPACT OF THE STUDY: The data from this study will be used to design oligonucleotide probe specific for bifidobacteria and to study the gene encoded F6PPK.