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KMID : 0545120010110050838
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Journal of Microbiology and Biotechnology
2001 Volume.11 No. 5 p.838 ~ p.844
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Fuculose-1-Phosphate Aldolase of Methanococcus jannaschii
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Lee, Bong Hwan
Yu, Yeon Gyu/Kim, Bok Hwan/Choi, Jung Do/Yoon, Moon Young
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Abstract
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The enzyme Fuc aldolase from Methanococcus jannaschii that catalyzes the aldol condensation of DHAP and L-lactaldehyde to give fuculose-l-phosphate was inactivated by DEP. The inactivation was pseudo first-order in the enzyme and DEP, which was biphasic. A pseudo second-order rate constant of 120M^-1min^-1 was obtained at pH 6.0 and 25℃. Quantifying the increase in absorbance at 240 ㎚ showed that four histidine residues per subunit were modified during the nearly complete inactivation. The statistical analysis and the time course of the modification suggested that two or three histidine residues were essential for activity. The rate of inactivation was dependent on the pH, and the pH inactivation data implied the involvement of an amino acid residue with a pK_a value of 5.7. Fuc aldolase was protected against DEP inactivation by DHAP, indicating that the histidine residues were located at the active site of Fuc aldolase. DL-Glyceraldehyde, as an alternative substrate to L-lactaldehyde, showed no specific protection for Fuc aldolase.
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