TY  - JOUR
ID  - open475
UR  - http://www.benthamdirect.org/pages/content.php?PPL/2011/00000018/00000007/0003E
IS  - 7
A1  - Kumar, Vijay
A1  - Saxena, Neetu
A1  - Sarma, Monika
A1  - Radha Kishan, K V
N2  - 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.
VL  - 18
TI  - Carboxylated lysine is required for higher activities in Hydantoinases.
AV  - none
EP  - 9
N1  - Copyright of this article belongs to Bentham Science
Y1  - 2011///
PB  - Bentham Science
JF  - Protein and peptide letters
KW  - Metalloenzyme
KW  -  lysine modifications
KW  -  TIM-barrel
KW  -  nucleophilicity of water
KW  -  enzyme activity 
SN  - 1875-5305
SP  - 663
ER  -