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== Publication Abstract from PubMed ==

Cys116, Lys240&lt;sup&gt;*&lt;/sup&gt;, and Asp241&lt;sup&gt;*&lt;/sup&gt; (asterisks indicate residues from the second subunit of the active dimer) at the active site of L-methionine gamma-lyase of Pseudomonas putida (MGL_Pp) are highly conserved among heterologous MGLs. In a previous study, we found that substitution of Cys116 for His led to a drastic increase in activity toward L-cysteine and a decrease in that toward L-methionine. In this study, we examined some properties of the C116H mutant by kinetic analysis and 3D structural analysis. We assumed that substitution of Cys116 for His broke the original hydrogen-bond network and that this induced a significant effect of Tyr114 as a general acid catalyst, possibly due to the narrow space in the active site. The C116H mutant acquired a novel beta-elimination activity and lead a drastic conformation change in the histidine residue at position 116 by binding the substrate, suggesting that this His residue affects the reaction specificity of C116H. Furthermore, we suggest that Lys240&lt;sup&gt;*&lt;/sup&gt; is important for substrate recognition and structural stability and that Asp241&lt;sup&gt;*&lt;/sup&gt; is also involved in substrate specificity in the elimination reaction. Based on this, we suggest that the hydrogen-bond network among Cys116, Lys240&lt;sup&gt;*&lt;/sup&gt;, and Asp241&lt;sup&gt;*&lt;/sup&gt; contributes to substrate specificity that is, to L-methionine recognition at the active site in MGL_Pp.

The Role of Amino Acid Residues in the Active Site of &lt;small&gt;L&lt;/small&gt;-Methionine gamma-lyase from &lt;i&gt;Pseudomonas putida&lt;/i&gt;.,Fukumoto M, Kudou D, Murano S, Shiba T, Sato D, Tamura T, Harada S, Inagaki K Biosci Biotechnol Biochem. 2012 Jul 23;76(7):1275-84. Epub 2012 Jul 7. PMID:22785484<ref>PMID:22785484</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>

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== References ==

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