Effects of Various Inhibitors on ?-galactosidase Purified from the Thermoacidophilic Alicyclobacillus acidocaldarius Subsp Rittmannii Isolated from Antarctica

beta-Galactosidase purified from the thermoacidophilic Alicyclobacillus acidocaldarius subsp. rittmannii isolated from Antarctica is a member of the GH42 family. The enzyme was not effected by various concentrations of its reaction product glucose, but was greatly inhibited by the other reaction pro...

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Bibliographic Details
Published in:Biotechnology and Bioprocess Engineering
Main Authors: Guven, Reyhan Gul, Kaplan, Alevcan, Guven, Kemal, Matpan, Fatma, Dogru, Mehmet
Format: Article in Journal/Newspaper
Language:English
Published: Korean Soc Biotechnology & Bioengineering 2011
Subjects:
Beta-Galactosidase
Metal Ion Chelators
Inhibition
Galactose
Pmcb And Pmsf
Antarc*
Antarctica
Online Access:https://hdl.handle.net/11468/14907
https://doi.org/10.1007/s12257-010-0070-7
Description
Summary:beta-Galactosidase purified from the thermoacidophilic Alicyclobacillus acidocaldarius subsp. rittmannii isolated from Antarctica is a member of the GH42 family. The enzyme was not effected by various concentrations of its reaction product glucose, but was greatly inhibited by the other reaction product galactose using both substrates, ONPG and lactose. Linewever-Burk plot analysis derived from both ONPG and lactose hydrolysis results showed that galactose is a mixed-type inhibitor of the purified beta-galactosidase. The enzyme was slightly activated by Mg(2+) (13% at 20 mM), while inhibited at higher concentrations of Ca(+2) (33% at 10 mM), Zn(+2) (86% at 8 mM) and Cu(+2) (87% at 4 mM). The enzyme activity was not significantly altered by the metal ion chelators EDTA and 1,10-phenanthroline up to 20 mM, indicating that this enzyme is not a metalloenzyme. 2-Mercaptoethanol and DTT were found to enhance beta-galactosidase activity, while p-chloromercuribenzoic acid (PCMB) completely inhibited enzymatic activity (97% at 1 mM; 99.7% at 2 mM), indicating at least one essential Cys residue modified by the reagents in the active site of beta-galactosidase. Iodoacetamide and N-ethylmaleimide had little effect on the beta-galactosidase. Phenylmethylsulfonyl fluoride (PMSF) inhibited the enzyme strongly (19.8% at 1 mM; 71.9% at 10 mM), also showing the participation of serine for enzyme activity.

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