Characterization of a purified beta-fructofuranosidase from Bifidobacterium infantis ATCC 15697.
OBJECTIVE
To characterize the beta-fructofuranosidase of Bifidobacterium infantis ATCC 15697 and to compare it with other bacterial beta-fructofuranosidases.


RESULTS
The beta-fructofuranosidase of B. infantis ATCC 15697 was purified 46.8 times over the crude extract by anion exchange chromatography, ultrafiltration and gel filtration. The sequence of 15 amino acid residues of the NH2 terminal was determined. This enzyme was a monomeric protein (Mr 70 kDa) with beta-fructofuranosidase and invertase activities. The isoelectric point was pH 4.3, the optimum pH 6.0 and pKas (4.5 and 7.2) of two active groups were obtained. The activities were inhibited by Hg2+ and p-chloromercuribenzoic acid (pCMB). The optimal temperature was 37 degrees C and activities were unstable at 55 degrees C. beta-fructofuranosidase activity was more efficient than that of invertase with Vm/Km ratios of 0.65 and 0.025 x 10-3 l min(-1) mg(-1), respectively. The enzyme catalyses the hydrolysis of fructo-oligosaccharides, sucrose and inulin at relative velocities of 100, 10 and 6, respectively.


CONCLUSIONS
The enzyme of B. infantis ATCC 15697 is an exo-inulinase which has beta-fructofuranosidase and invertase activities. This protein was different from the beta-fructofuranosidase of another strain of B. infantis (B. infantis JCM no. 7007).


CONCLUSIONS
A better knowledge of bacterial beta-fructofuranosidases, especially from bifidobacteria, has been gained.
Warchol
M
M
Laboratoire de Biochimie des Bactéries Gram +, Université Henri Poincaré-Nancy I, Faculté des Sciences et Techniques, Vandoeuvre-lès-Nancy Cedex, France.
Perrin
S
S
Grill
J-P
JP
Schneider
F
F
D001644:Bifidobacterium / Q000201:enzymology* / Q000254:growth & development; D004591:Electrophoresis, Polyacrylamide Gel; D006026:Glycoside Hydrolases / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D013696:Temperature; D043324:beta-Fructofuranosidase
D006026:Glycoside Hydrolases; D043324:beta-Fructofuranosidase