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Ortho phosphate anion enhances the stability and activity of endoxylanase from Bacillus sp.
Author(s) -
Park Min Tae,
Lee Myung Seop,
Choi Ja Young,
Kim Sun Chang,
Lee Gyun Min
Publication year - 2001
Publication title -
biotechnology and bioengineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.136
H-Index - 189
eISSN - 1097-0290
pISSN - 0006-3592
DOI - 10.1002/1097-0290(20000220)72:4<434::aid-bit1005>3.0.co;2-6
Subject(s) - chemistry , biochemistry
Endoxylanase, for which the optimum temperature is 60°C (optimum pH 7), is labile to heat. Because the isoelectric point (pI) value of this xylanase is 10.6, the net charge of this enzyme is positive at pH 7. Thus, ions are likely to influence its enzyme structure and the thermal stability of endoxylanase may improve. Among the various ions tested, ortho phosphate anion (HPO 4 2− ) was found to significantly improve not only the stability but the activity of xylanase. When K 2 HPO 4 concentration was increased from 50 m M to 1.2 M , the T m value of xylanase was increased from 60.0°C to 74.5°C. The affinity of xylanase on xylan also increased along with K 2 HPO 4 concentration. Thus, the xylanase activity at 0.6 M K 2 HPO 4 was 2.3‐fold higher than that at 50 m M K 2 HPO 4 , and 120.2‐fold higher than that in 40 m M MOPS buffer. This enhanced activity in the presence of K 2 HPO 4 probably takes place because the ortho phosphate anion affects the binding and catalytic residues of endoxylanase. © 2001 John Wiley & Sons, Inc. Biotechnol Bioeng 72: 434–440, 2001.