EFFECT OF TEMPERATURE ON SUBSITE MAP OF BACILLUS LICHENIFORMIS α -AMYLASE

Kandra, Lili and Remenyik, Judit and Gyémánt, Gyöngyi and Lipták, A. and Lipták, A. and Lipták, A. (2006) EFFECT OF TEMPERATURE ON SUBSITE MAP OF BACILLUS LICHENIFORMIS α -AMYLASE. Acta Biologica Hungarica, 57 (3). pp. 367-375. ISSN 0236-5383

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Abstract

To elucidate how temperature effects subsite mapping of a thermostable α -amylase from Bacillus licheniformis (BLA), a comparative study was performed by using 2-chloro-4-nitrophenyl (CNP) β -mal- tooligosides with degree of polymerisation (DP) 4–10 as model substrates. Action patterns, cleavage frequencies and subsite binding energies were determined at 50 °C, 80 °C and 100 °C. Subsite map at 80 °C indicates more favourable bindings compared to the hydrolysis at 50 °C. Hydrolysis at 100 °C resulted in a clear shift in the product pattern and suggests significant differences in the active site archi- tecture. Two preferred cleavage modes were seen for all substrates in which subsite (+2) and (+3) were dominant, but CNP-G 1 was never formed. In the preferred binding mode of shorter oligomers, CNP-G 2 serves as the leaving group (79%, 50%, 59% and 62% from CNP-G 4 , CNP-G 5 , CNP-G 6 and CNP-G 7 , respectively), while CNP-G 3 is the dominant hydrolysis product from CNP-G 8 , CNP-G 9 , and CNP-G 10 (62%, 68% and 64%, respectively). The high binding energy value (–17.5 kJ/mol) found at subsite (+2) is consistent with the significant formation of CNP-G 2 . Subsite mapping at 80 °C and 100 °C confirms that there are no further binding sites despite the presence of longer products

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