EC Number   |
Reaction |
Reference |
|---|
    3.5.1.19 | nicotinamide + H2O = nicotinate + NH3 |
- |
- |
| 3.5.1.19 | nicotinamide + H2O = nicotinate + NH3 |
catalytic mechanism in two stages: (i) formation of a tetrahedral thioester enzyme-substrate intermediate (with the sulfur of Cys136 nucleophilically attacks the nicotinamidase substrate's carbonyl carbon while concomitantly the Cys136-SH thiol proton is transferred onto the substrate's amide group nitrogen) and (ii) hydrolysis of the thioester bond to give the products, overview. The catalytic triad comprises Lys103, Asp9, and Cys136, substrate binding and roles of active site residues of the enzyme from Streptococcus pneumoniae. The active site Lys103 likely plays a role in stabilizing the thiolate of Cys136 during the reaction |
734741 |
| 3.5.1.19 | nicotinamide + H2O = nicotinate + NH3 |
the active site Cys159, conserved and essential, is located at the N-terminus of a6 at one side of the active site with the Zn2+ ion positioned on the other side. The metal ion is bound tightly in the AbPncA active site. The reaction proceeds in a four-stage mechanism via a tetrahedral and an acyl intermediate, overview |
710862 |
