scholarly journals Probing the mechanisms for the selectivity and promiscuity of methyl parathion hydrolase

2016 ◽  
Vol 374 (2080) ◽  
pp. 20160150 ◽  
Author(s):  
Miha Purg ◽  
Anna Pabis ◽  
Florian Baier ◽  
Nobuhiko Tokuriki ◽  
Colin Jackson ◽  
...  
Keyword(s):  
Transition State ◽  
Metal Ions ◽  
Metal Ion ◽  
Methyl Parathion ◽  
Model Systems ◽  
Functional Evolution ◽  
Methyl Parathion Hydrolase ◽  
Wide Range ◽  
Metal Metal ◽  
Parathion Hydrolase

Diverse organophosphate hydrolases have convergently evolved the ability to hydrolyse man-made organophosphates. Thus, these enzymes are attractive model systems for studying the factors shaping enzyme functional evolution. Methyl parathion hydrolase (MPH) is an enzyme from the metallo-β-lactamase superfamily, which hydrolyses a wide range of organophosphate, aryl ester and lactone substrates. In addition, MPH demonstrates metal-ion-dependent selectivity patterns. The origins of this remain unclear, but are linked to open questions about the more general role of metal ions in functional evolution and divergence within enzyme superfamilies. Here, we present detailed mechanistic studies of the paraoxonase and arylesterase activities of MPH complexed with five different transition metal ions, and demonstrate that the hydrolysis reactions proceed via similar pathways and transition states. However, while it is possible to discern a clear structural origin for the selectivity between different substrates , the selectivity between different metal ions appears to lie instead in the distinct electrostatic properties of the metal ions themselves, which causes subtle changes in transition state geometries and metal–metal distances at the transition state rather than significant structural changes in the active site. While subtle, these differences can be significant for shaping the metal-ion-dependent activity patterns observed for this enzyme. This article is part of the themed issue ‘Multiscale modelling at the physics–chemistry–biology interface’.

Crystal Structure of Methyl Parathion Hydrolase from Pseudomonas sp. WBC-3

2005 ◽  
Vol 353 (3) ◽  
pp. 655-663 ◽  
Author(s):  
Yan-Jie Dong ◽  
Mark Bartlam ◽  
Lei Sun ◽  
Ya-Feng Zhou ◽  
Zhi-Ping Zhang ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Methyl Parathion ◽  
Pseudomonas Sp ◽  
Methyl Parathion Hydrolase ◽  
Parathion Hydrolase

Metal Ion Release after Hip and Knee Arthroplasty – Causes, Biological Effects and Diagnostics

2019 ◽  
Vol 158 (04) ◽  
pp. 369-382 ◽  
Author(s):  
Jörg Lützner ◽  
Klaus-Peter Günther ◽  
Anne Postler ◽  
Michael Morlock
Keyword(s):  
Metal Ions ◽  
Metal Ion ◽  
Biological Effects ◽  
Ion Concentration ◽  
Blood Levels ◽  
Ceramic Head ◽  
Ion Release ◽  
Imaging Results ◽  
Metal Ion Release ◽  
Metal Metal

AbstractAll metal implants in human bodies corrode which results in metal ions release. This is not necessarily a problem and represents for most patients no hazard. However, if a critical metal ion concentration is exceeded, local or rarely systemic problems can occur. This article summarizes the mechanisms of metal ion release and its clinical consequences. Several situations can result in increased metal ion release: metal-on-metal hip arthroplasties with increased wear, increased micromotion at taper interfaces, direct metal-metal contact (polyethylene wear, impingement), erroneously used metal heads after ceramic head fracture. Possible problems are in most cases located close to the concerned joint. Furthermore, there are reports about toxic damage to several organs. Most of these reports refer to erroneously used metal heads in revisions after a broken ceramic head. There is currently no evidence of carcinogenic or teratogenic effects of implants but data is not sufficient to exclude possible effects. Cobalt and chromium blood levels (favorably in whole blood) should be measured in patients with suspected elevated metal ions. According to current knowledge levels below 2 µg/l seem to be uncritical, levels between 2 and 7 µg/l are considered borderline with unknown biological consequences and levels above 7 µg/l indicate a local problem which should be further diagnosed. Metal ion levels always need to be interpreted together with clinical symptoms and imaging results.

Alkali metal ion catalysis in nucleophilic displacement by ethoxide ion on p-nitrophenyl phenylphosphonate: Evidence for multiple metal ion catalysis

2003 ◽  
Vol 81 (1) ◽  
pp. 53-63 ◽  
Author(s):  
Erwin Buncel ◽  
Ruby Nagelkerke ◽  
Gregory RJ Thatcher
Keyword(s):  
Alkali Metal ◽  
Transition State ◽  
Metal Ions ◽  
Metal Ion ◽  
Alkali Metal Ions ◽  
Phosphoryl Transfer ◽  
Alkali Metal Ion ◽  
Nucleophilic Displacement ◽  
Displacement Reactions ◽  
Metal Ion Catalysis

In continuation of our studies of alkali metal ion catalysis and inhibition at carbon, phosphorus, and sulfur centers, the role of alkali metal ions in nucleophilic displacement reactions of p-nitrophenyl phenylphosphonate (PNPP) has been examined. All alkali metal ions studied acted as catalysts. Alkali metal ions added as inert salts increased the rate while decreased rate resulted on M+ complexation with 18-crown-6 ether. Kinetic analysis indicated the interaction of possibly three potassium ions, four sodium ions, and five lithium ions in the transition state of the reactions of ethoxide with PNPP. Pre-association of the anionic substrate with two metals ions in the ground state gave the best fit to the experimental data of the sodium system. Thus, the study gives evidence of the role of several metal ions in nucleophilic displacement reactions of ethoxide with anionic PNPP, both in the ground state and in the transition state. Molecular modeling of the anionic transition state implies that the size of the monovalent cation and the steric requirement of the pentacoordinate transition state are the primary limitations on the number of cations that can be brought to bear to stabilize the transition state and catalyze nucleophilic substitution at phosphorus. The bearing of the present work on metal ion catalysis in enzyme systems is discussed, in particular enzymes that catalyze phosphoryl transfer, which often employ multiple metal ions. Our results, both kinetic and modeling, reveal the importance of electrostatic stabilization of the transition state for phosphoryl transfer that may be effected by multiple cations, either monovalent metal ions or amino acid residues. The more such cations can be brought into contact with the anionic transition state, the greater the catalysis observed.Key words: alkali metal ion catalysis, nucleophilic displacement at phosphorus, multiple metal ion catalysis, phosphoryl transfer.

Comparative inhibition of hepatic hydroxymethylbilane synthase by both hard and soft metal cations

1984 ◽  
Vol 62 (1) ◽  
pp. 49-54 ◽  
Author(s):  
D. J. Farmer ◽  
B. R. Hollebone
Keyword(s):  
Metal Ions ◽  
Metal Ion ◽  
Ph Dependence ◽  
Sprague Dawley ◽  
Sprague Dawley Rats ◽  
Wide Range ◽  
Chemical Behaviour ◽  
Soft Metal ◽  
Hardness Values

The in vitro inhibition of hydroxymethylbilane synthase (EC 4.3.1.8, uroporphyrinogen I synthetase) obtained from livers of Sprague–Dawley rats has been studied with a wide range of di- and tri-valent metal ions. After purification by cell lysis, heat treatment, and centrifugation, the stable, soluble enzyme yielded sigmoidal inhibition curves with increasing concentrations of each of the 16 test ions. Using the negative logarithm of metal concentration for 50% inhibition (the pM50 value), the metal ions could be classified according to their Klopman hardness values. Very soft ions including Hg2+, intermediate ions including Cr3+, and very hard ions including Al3+ all yielded large pM50 values indicating strong inhibition. In comparison to known metal-ion chemical behaviour, these three ions could indicate three different types of inhibitory binding sites at or near the active site: Hg2+ corresponding to sulfur in cysteine, Cr3+ corresponding to nitrogen in histidine, and Al3+ corresponding to oxygen in carboxyl groups. The presence of the first two sites is also indicated by the pH dependence of activity.

Twin-Arginine Translocation of Methyl Parathion Hydrolase inBacillus subtilis

2010 ◽  
Vol 44 (19) ◽  
pp. 7607-7612 ◽  
Author(s):  
Chao Yang ◽  
Cunjiang Song ◽  
Roland Freudl ◽  
Ashok Mulchandani ◽  
Chuanling Qiao
Keyword(s):  
Methyl Parathion ◽  
Methyl Parathion Hydrolase ◽  
Twin Arginine Translocation ◽  
Parathion Hydrolase

Application of methyl parathion hydrolase (MPH) as a labeling enzyme

2008 ◽  
Vol 390 (8) ◽  
pp. 2133-2140 ◽  
Author(s):  
Wei Yang ◽  
Ya-Feng Zhou ◽  
He-Ping Dai ◽  
Li-Jun Bi ◽  
Zhi-Ping Zhang ◽  
...  
Keyword(s):  
Methyl Parathion ◽  
Methyl Parathion Hydrolase ◽  
Parathion Hydrolase

scholarly journals Isolation of Methyl Parathion-Degrading Strain M6 and Cloning of the Methyl Parathion Hydrolase Gene

2001 ◽  
Vol 67 (10) ◽  
pp. 4922-4925 ◽  
Author(s):  
Cui Zhongli ◽  
Li Shunpeng ◽  
Fu Guoping
Keyword(s):  
Nucleotide Sequence ◽  
Methyl Parathion ◽  
Genomic Library ◽  
Methyl Parathion Hydrolase ◽  
Organophosphate Hydrolase ◽  
Shotgun Cloning ◽  
Esherichia Coli ◽  
Parathion Hydrolase

ABSTRACT A degradative bacterium, M6, was isolated and presumptively identified as Plesiomonas sp. strain M6 was able to hydrolyze methyl parathion to p-nitrophenol. A novel organophosphate hydrolase gene designated mpd was selected from its genomic library prepared by shotgun cloning. The nucleotide sequence of the mpd gene was determined. The gene could be effectively expressed in Esherichia coli.

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