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Effects of buffer properties on cyclodextrin glucanotransferase reactions and cyclodextrin production from raw sago ( Cycas revoluta ) starch
Author(s) -
Kamaruddin Kamarulzaman,
Illias Rosli Md.,
Aziz Suraini Abdul,
Said Mamot,
Hassan Osman
Publication year - 2005
Publication title -
biotechnology and applied biochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.468
H-Index - 70
eISSN - 1470-8744
pISSN - 0885-4513
DOI - 10.1042/ba20040040
Subject(s) - cyclodextrin , chemistry , tris , yield (engineering) , ionic strength , phosphate , buffer solution , starch , ionic liquid , chromatography , nuclear chemistry , organic chemistry , catalysis , biochemistry , aqueous solution , materials science , metallurgy
Results from the present study have shown that the ionic species of buffers, pH values and reaction temperature can affect the enzyme unit activities and product specificity of Toruzyme® (Novo Nordisk A/S Bagsvaerd, Denmark) CGTase (cyclodextrin glucanotransferase). Applying a similar reaction environment (acetate buffer, pH 6.0; temperature, 60 °C), the CGTase was found to be capable of producing pre dominantly β‐cyclodextrin from either raw or gelatinized sago ( Cycas revoluta ) starch. Changing the buffer from acetate to phosphate reduced the yield of β‐cyclodextrin from 2.48 to 1.42 mg/ml and also affected the product specificity, where production of both α‐ and β‐cyclodextrins were more pronounced. The decrease in the production of cyclodextrins in phosphate buffer was significant at both pH 6.0 and 7.0. However, changing the buffer to Tris/HCl (pH 7.0) showed a significant increase in β‐cyclodextrin production. Increasing the ionic strength of sodium acetate and Tris/HCl buffers at pH 6.0 and 7.0 to equivalent ionic strength of phosphate buffers showed no significant effects on cyclodextrin production. Higher yield of cyclodextrins at pH 7.0 when Tris/HCl was used might be due to the binding of chloride ions at the calcium‐binding sites of the CGTase, resulting in the shift of the optimum pH close to physiological environment, leading to an increase in the activities and specificity.