Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.5.1.4 (deaminase)
 5,113 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Fatty acid amide hydrolase (FAAH) is a member of the amidase signature family and is responsible for the hydrolytic deactivation of fatty acid amide neuromodulators, such as anandamide. FAAH carries an unusual catalytic triad consisting of Lys-Ser-Ser, which uniquely enables the enzyme to cleave amides and esters at similar rates. The acylation of 9Z-octadecenamide (oleamide, a FAAH reference substrate) has been widely investigated by computational methods, and those have shown that conformational fluctuations of the active site affect the reaction barrier. Empirical descriptors have been devised to provide a possible mechanistic explanation for such conformational effects, but a first-principles understanding is still missing. A comparison of FAAH acylation with a reference reaction in water suggests that transition-state stabilization is crucial for catalysis because the activation energy barrier falls by 6 kcal/mol in the presence of the active site. With this in mind, we have analyzed the enzymatic reaction using the differential transition-state stabilization (DTSS) approach to determine key active-site residues for lowering the barrier. We examined several QM/MM structures at the MP2 level of theory and analyzed catalytic effects with a variation-perturbation partitioning of the interaction energy into electrostatic multipole and penetration, exchange, delocalization, and correlation terms. Three residues - Thr236, Ser218, and one water molecule - appear to be essential for the stabilization of the transition state, a conclusion that is also reflected by catalytic fields and agrees with site-directed mutagenesis data. An analogous analysis for URB524, URB618, and URB694 (three potent representatives of covalent, carbamate-based FAAH inhibitors) confirms the importance of the residues involved in oleamide acylation, providing insight for future inhibitor design.
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PMID:Nonempirical energetic analysis of reactivity and covalent inhibition of fatty acid amide hydrolase. 2365 26

In arthropods, melanization plays a major role in the innate immune response to encapsulate and kill the invasive organisms. It is mediated by a serine protease cascade and is regulated by serpins. The identification of the molecular components of melanization and the regulation of those components are still unclear in Drosophila melanogaster, although some genetic research on the activation of melanization has been reported. Here we report that Drosophila serine protease MP2 directly cleaves both recombinant and native prophenoloxidase-1. Overexpression or repression of MP2 in flies resulted in increased and decreased rates of cleavage, respectively, of prophenoloxidase-1. Moreover, serine protease inhibitor Spn27A formed SDS-stable complexes with MP2, both in vitro and in vivo. The amidase activity of MP2 was inhibited efficiently by Spn27A. Spn27A also prevented MP2 from cleaving prophenoloxidase-1. Taken together, these results indicate that under our experimental conditions MP2 functions as a prophenoloxidase-activating protease, and that this function is inhibited by Spn27A. MP2 and Spn27A thus constitute a regulatory unit in the prophenoloxidase activation cascade in Drosophila. The combination of genetic, molecular genetic and biochemical approaches should allow further advances in our understanding of the prophenoloxidase-activating cascade in insects and indirectly shed further light on protease-cascades in humans and other vertebrates.
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PMID:Serine protease MP2 activates prophenoloxidase in the melanization immune response of Drosophila melanogaster. 2426 Feb 43