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

Aims: The kev enzyme in the fructose-6-phosphate shunt in bifidobacteria, F ructose-6-phosphate phosphoketolase (F6PPK; E.C. 4.1.2.22.), was purified t o electrophoretic homogeneity for the first time from Bifidobacterium longu m (BB536). Methods and Results: A three-step procedure comprising acetone fractionatio n followed bq fast protein liquid chromatography (FPLC) resulted in a 30-fo ld purification. The purified enzyme had a molecular mass of 300 +/- 5 kDa as determined by gel filtration. It is probably a tetramer containing two d ifferent subunits with molecular masses of. 93 +/- 1 kDa and 59 +/- 0.5 kDa , as determined by SDS-PAGE. Conclusions: The deduced N-terminal amino acid sequences of the two subunit s revealed no significant similarity between them and other proteins cr:hen compared to the data bases of EMBL and SWISS-PROT, indicating that this co uld 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 t he gene encoded F6PPK.