Polyethylene glycols enhance the thermostability of β-cyclodextrin glycosyltransferase from Bacillus circulans

• Published in: Food chemistry Vol. 164; pp. 17 - 22
• Main Authors: Li, Caiming, Li, Wenwen, Holler, Tod P., Gu, Zhengbiao, Li, Zhaofeng
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.12.2014; Elsevier
• Subjects: Bacillus - enzymology; Bacillus circulans; Bacterial Proteins - chemistry; beta-Cyclodextrins - chemistry; Biological and medical sciences; Circular Dichroism; Cyclodextrin; Cyclodextrin glycosyltransferase; Dichroism; Enzyme Stability; Fluorescence; Food toxicology; Foods; Glucosyltransferases - chemistry; Half-Life; Hot Temperature; Hydrophobic and Hydrophilic Interactions; Medical sciences; Molecular structure; Molecular weight; Polyethylene glycol; Polyethylene Glycols - chemistry; Protein Structure, Secondary; Spectrometry, Fluorescence; Thermal stability; Thermostability; Toxicology; Thermostability; Cyclodextrin glycosyltransferase; Cyclodextrin; Polyethylene glycol; EC 2.4.1.19; Bacillus circulans; Oligosaccharide; Bacillaceae; Thermal stability; Ethylene oxide polymer; β-Cyclodextrin; Bacillales; Bacteria
• ISSN: 0308-8146; 1873-7072
• DOI: 10.1016/j.foodchem.2014.05.013

•PEG 400 enhances the activity of β-cyclodextrin glycosyltransferase by 20%.•PEG 1000 prolongs the half-life of this enzyme at 60°C by 6.5-fold.•Fluorescence spectroscopy shows that PEGs protect tertiary structure.•Circular dichroism shows that PEGs protect secondary structure. We investigated the ability of six polyethylene glycols (PEGs), with molecular weights ranging from 400 to 20,000Da, to enhance the thermostability of β-cyclodextrin glycosyltransferase (β-CGTase) from Bacillus circulans. We found that PEGs with different molecular weights could activate and stabilize this β-CGTase, but to different degrees. The most significant increase (about 20%) in β-cyclodextrin-forming activity was achieved by adding 10–15% PEG 400. PEGs with low molecular weights also significantly enhanced the thermostability of β-CGTase; 15% PEG 1000 prolonged its half-life at 60°C by 6.5-fold, compared to a control. Fluorescence spectroscopy and circular dichroism analysis indicated that PEGs helped protect the tertiary and secondary structure of β-CGTase, respectively. This study provides an effective approach for improving the thermostability of CGTases and related enzymes.