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Effects of Alcohols and Compatible Solutes on the Activity of β-Galactosidase.
MedLine Citation:
PMID:  23274723     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
During alcoholic fermentation, the products build up and can, ultimately, kill the organism due to their effects on the cell's macromolecular systems. The effects of alcohols on the steady-state kinetic parameters of the model enzyme β-galactosidase were studied. At modest concentrations (0 to 2 M), there was little effect of methanol, ethanol, propanol and butanol on the kinetic constants. However, above these concentrations, each alcohol caused the maximal rate, V (max), to fall and the Michaelis constant, K (m), to rise. Except in the case of methanol, the chaotropicity of the solute, rather than its precise chemical structure, determined and can, therefore, be used to predict inhibitory activity. Compounds which act as compatible solutes (e.g. glycerol and other polyols) generally reduced enzyme activity in the absence of alcohols at the concentration tested (191 mM). In the case of the ethanol- or propanol-inhibited β-galactosidase, the addition of compatible solutes was unable to restore the enzyme's kinetic parameters to their uninhibited levels; addition of chaotropic solutes such as urea tended to enhance the effects of these alcohols. It is possible that the compatible solutes caused excessive rigidification of the enzyme's structure, whereas the alcohols disrupt the tertiary and quaternary structure of the protein. From the point of view of protecting enzyme activity, it may be unwise to add compatible solutes in the early stages of industrial fermentations; however, there may be benefits as the alcohol concentration increases.
Authors:
Andrew N W Bell; Emma Magill; John E Hallsworth; David J Timson
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-12-30
Journal Detail:
Title:  Applied biochemistry and biotechnology     Volume:  -     ISSN:  1559-0291     ISO Abbreviation:  Appl. Biochem. Biotechnol.     Publication Date:  2012 Dec 
Date Detail:
Created Date:  2012-12-31     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  8208561     Medline TA:  Appl Biochem Biotechnol     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Affiliation:
School of Biological Sciences, Medical Biology Centre, Queen's University Belfast, 97 Lisburn Road, Belfast, BT9 7BL, UK.
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