The effect of glutaraldehyde on the conformational properties of Kluyveromyces
lactis β-galactosidase was determined. The optimum substrate of the enzyme
interchanged from lactose to sucrose when it reacted with a certain concentration of
glutaraldehyde. Its mechanism was studied by detecting the changes in fluorescence
absorption. This is the first discovery that β-galactosidase can be converted to another
kind of enzyme which can catalyze sucrose to produce glucose rather than lactose. On
the basis of this phenomenon, an amperometric sucrose biosensor using β-galactosidase
modified by glutaraldehyde as the immobilized enzyme and poly-β-cyclodextrin as the
carrier was prepared. The response characteristic of the sucrose biosensor was also
studied. Under optimum conditions, the current response had a linear relationship with
the sucrose concentration in the range of 0–2 g/dL with a correlation coefficient of 0.9996
and a response time of < 30 s. The sucrose biosensor exhibited excellent diffusion and
stability, and retained its sensitivity after 7 d of continuous use. This sucrose biosensor
is expected to provide an effective and economical alternative for the quick and sensitive
detection of sucrose in the food and beverage industries in the future.
