Carboxylated lysine is required for higher activities in Hydantoinases.

Kumar, Vijay and Saxena, Neetu and Sarma, Monika and Radha Kishan, K V (2011) Carboxylated lysine is required for higher activities in Hydantoinases. Protein and peptide letters, 18 (7). pp. 663-9. ISSN 1875-5305

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Hydantoinases are industrial enzymes with varying degree of activities on variable substrates to form different products. Although, few of the hydantoinase structures were known recently, the functional details and active site mechanism were not clearly understood yet. In a structure determination effort we reported that Bacillus sp. AR9 hydantoinase contains uncarboxylated lysine in the active site, whereas all the other hydantoinases have a carboxylated active site lysine. Here we describe the importance of carboxylated lysine for differential activities by making lysine mutations as well as carboxylating the lysine in a D-hydantoinase from Bacillus sp. AR9. The lysine to alanine and lysine to arginine mutations showed reduced activities whereas carboxylation of the lysine has enhanced the activity. Theoretical studies involving the calculation of electrostatic potentials for the hydroxide ion between the two metal ions present in the active site suggest that the presence of carboxylated lysine increases the nucleophilicity of the hydroxide.

Item Type: Article
Additional Information: Copyright of this article belongs to Bentham Science
Uncontrolled Keywords: Metalloenzyme, lysine modifications, TIM-barrel, nucleophilicity of water, enzyme activity
Subjects: Q Science > QD Chemistry
Depositing User: Dr. K.P.S.Sengar
Date Deposited: 09 Dec 2011 06:57
Last Modified: 09 Dec 2011 06:57

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