A new kinetic model of recombinant beta-galactosidase from Kluyveromyces lactis for both hydrolysis and transgalactosylation reactions.
Previous models based on the Michaelis-Menten kinetic equation, that glucose was not used as an acceptor, did not explain our experimental data for lactose conversion by a recombinant beta-galactosidase from Kluyeromyces lactis. In order to create a new kinetic model based on the data, the effects of galactose and glucose on beta-galactosidase activity were investigated. Galactose acted as an inhibitor at low concentrations of galactose and lactose, but did not inhibit the activity of beta-galactosidase at high concentrations of galactose (above 50mM) and lactose (above 100mM). The addition of glucose at concentrations below 50mM resulted in an increased reaction rate. A new model of K. lactis beta-galactosidase for both hydrolysis and transgalactosylation reactions with glucose and lactose as acceptors was proposed. The proposed model was fitted well to the experimental data of the time-course reactions for lactose conversion by K. lactis beta-galactosidase at various concentrations of substrate.
Kim
Chang Sup
CS
Department of Bioscience and Biotechnology, Sejong University, Seoul 143-747, Republic of Korea.
Ji
Eun-Su
ES
Oh
Deok-Kun
DK
D004305:Dose-Response Relationship, Drug; D004926:Escherichia coli / Q000378:metabolism; D005690:Galactose / Q000737:chemistry*; D005947:Glucose / Q000737:chemistry; D006868:Hydrolysis; D007700:Kinetics; D007716:Kluyveromyces / Q000201:enzymology*; D007785:Lactose / Q000737:chemistry; D008956:Models, Chemical; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000737:chemistry*; D013997:Time Factors; D001616:beta-Galactosidase / Q000737:chemistry* / Q000378:metabolism
D011994:Recombinant Proteins; D001616:beta-Galactosidase; D005947:Glucose; D007785:Lactose; D005690:Galactose