X-ray crystal structures of the Yersinia tyrosine phosphatase (PTPase) in complex with tungstate and nitrate have been solved to 2.4-Å resolution. Tetrahedral tungstate, WO 4 2؊ , is a competitive inhibitor of the enzyme and is isosteric with the substrate and product of the catalyzed reaction. Planar nitrate, NO 3 ؊ , is isosteric with the PO 3 moiety of a phosphotransfer transition state. The crystal structures of the Yersinia PTPase with and without ligands, together with biochemical data, permit modeling of key steps along the reaction pathway. These energy-minimized models are consistent with a general acid-catalyzed, in-line displacement of the phosphate moiety to Cys 403 on the enzyme, followed by attack by a nucleophilic water molecule to release orthophosphate. This nucleophilic water molecule is identified in the crystal structure of the nitrate complex. The active site structure of the PTPase is compared to alkaline phosphatase, which employs a similar phosphomonoester hydrolysis mechanism. Both enzymes must stabilize charges at the nucleophile, the PO 3 moiety of the transition state, and the leaving group. Both an associative (bond formation preceding bond cleavage) and a dissociative (bond cleavage preceding bond formation) mechanism were modeled, but a dissociative-like mechanism is favored for steric and chemical reasons. Since nearly all of the 47 invariant or highly conserved residues of the PTPase domain are clustered at the active site, we suggest that the mechanism postulated for the Yersinia enzyme is applicable to all the PTPases.

No abstract

No abstract

Neutral endopeptidase (NEP) is a mammalian zinc metalloprotease involved in the inactivation of a wide variety of regulatory peptides such as enkephalins and atrial natiuretic factor. The soluble extracellular domain of NEP (sNEP) was expressed in the methylotrophic yeast Pichia pastoris. The protein was puri®ed to homogeneity and single crystals have been obtained. Enzymatic deglycosylation of the enzyme was essential for the production of crystals suitable for X-ray analysis for both the NEP±phosphoramidon binary complex and the apo enzyme.

No abstract

This is a corrigendum and clarification on behalf of the authors. Figure 4 (including the figure legend) in the original version of this article has been corrected as follows:In addition, the authors would like to emphasize that the refinery case study reported in this paper came from the Thai LCI database development of petroleum and petrochemical industry project phase 1 (2006)(2007). The current available LCI data on the Thai LCI database website were from the project phase 2 (2008)(2009)(2010)(2011). Presently, the project phase 3 is on-going (2015-present), and the updated data will be available in the near future.The online version of the original article can be found at http://dx.doi.