3-Dimensional interactions between inositol monophosphatase and its substrates, inhibitors and metal ion cofactors

1995 ◽  
pp. 2709 ◽  
Author(s):  
John Wilkie ◽  
Andrew G. Cole ◽  
David Gani
Keyword(s):  
Metal Ion ◽  
Inositol Monophosphatase ◽  
3 Dimensional ◽  
Metal Ion Cofactors

scholarly journals Transmembrane signal transduction by cofactor transport

2021 ◽  
Author(s):  
Istvan Kocsis ◽  
Yudi Ding ◽  
Nicholas H. Williams ◽  
Christopher A. Hunter
Keyword(s):  
Signal Transduction ◽  
Lipid Bilayer ◽  
Metal Ion ◽  
Bilayer Membrane ◽  
Ester Hydrolysis ◽  
Lipid Bilayer Membrane ◽  
Metal Ion Cofactors

Synthetic transducers transport externally added metal ion cofactors across the lipid bilayer membrane of vesicles to trigger catalysis of ester hydrolysis in the inner compartment. Signal transduction activity is modulated by hydrazone formation.

Structural elucidation of a dual-activity PAP phosphatase-1 fromEntamoeba histolyticacapable of hydrolysing both 3′-phosphoadenosine 5′-phosphate and inositol 1,4-bisphosphate

2014 ◽  
Vol 70 (7) ◽  
pp. 2019-2031 ◽  
Author(s):  
Khaja Faisal Tarique ◽  
Syed Arif Abdul Rehman ◽  
S. Gourinath
Keyword(s):  
Metal Ions ◽  
Metal Ion ◽  
Genomic Analysis ◽  
Inositol Polyphosphate ◽  
Inositol Monophosphatase ◽  
Native Form ◽  
Catalytic Loop ◽  
Important Regulator ◽  
Living Organisms ◽  
Toxic Byproduct

The enzyme 3′-phosphoadenosine 5′-phosphatase-1 (PAP phosphatase-1) is a member of the Li+-sensitive Mg2+-dependent phosphatase superfamily, or inositol monophosphatase (IMPase) superfamily, and is an important regulator of the sulfate-activation pathway in all living organisms. Inhibition of this enzyme leads to accumulation of the toxic byproduct 3′-phosphoadenosine 5′-phosphate (PAP), which could be lethal to the organism. Genomic analysis ofEntamoeba histolyticasuggests the presence of two isoforms of PAP phosphatase. The PAP phosphatase-1 isoform of this organism is shown to be active over wide ranges of pH and temperature. Interestingly, this enzyme is inhibited by submillimolar concentrations of Li+, while being insensitive to Na+. Interestingly, the enzyme showed activity towards both PAP and inositol 1,4-bisphosphate and behaved as an inositol polyphosphate 1-phosphatase. Crystal structures of this enzyme in its native form and in complex with adenosine 5′-monophosphate have been determined to 2.1 and 2.6 Å resolution, respectively. The PAP phosphatase-1 structure is divided into two domains, namely α+β and α/β, and the substrate and metal ions bind between them. This is a first structure of any PAP phosphatase to be determined from a human parasitic protozoan. This enzyme appears to function using a mechanism involving three-metal-ion assisted catalysis. Comparison with other structures indicates that the sensitivity to alkali-metal ions may depend on the orientation of a specific catalytic loop.

Structural Studies of Metal Binding by Inositol Monophosphatase: Evidence for Two-Metal Ion Catalysis

Biochemistry ◽  
1994 ◽  
Vol 33 (32) ◽  
pp. 9468-9476 ◽  
Author(s):  
Roger Bone ◽  
Lori Frank ◽  
James P. Springer ◽  
John R. Atack
Keyword(s):  
Metal Binding ◽  
Metal Ion ◽  
Structural Studies ◽  
Inositol Monophosphatase ◽  
Metal Ion Catalysis

scholarly journals Characterization of a Tetrameric Inositol Monophosphatase from the Hyperthermophilic Bacterium Thermotoga maritima

1999 ◽  
Vol 65 (10) ◽  
pp. 4559-4567 ◽  
Author(s):  
Liangjing Chen ◽  
Mary F. Roberts
Keyword(s):  
Metal Ion ◽  
Quaternary Structure ◽  
De Novo ◽  
Thermotoga Maritima ◽  
Heat Stability ◽  
Inositol Monophosphatase ◽  
Heat Stable ◽  
Hyperthermophilic Bacterium ◽  
A Subunit ◽  
Rate Of Hydrolysis

ABSTRACT Inositol monophosphatase (I-1-Pase) catalyzes the dephosphorylation step in the de novo biosynthetic pathway of inositol and is crucial for all inositol-dependent processes. An extremely heat-stable tetrameric form of I-1-Pase from the hyperthermophilic bacterium Thermotoga maritima was overexpressed in Escherichia coli. In addition to its different quaternary structure (all other known I-1-Pases are dimers), this enzyme displayed a 20-fold higher rate of hydrolysis of d-inositol 1-phosphate than of thel isomer. The homogeneous recombinant T. maritima I-1-Pase (containing 256 amino acids with a subunit molecular mass of 28 kDa) possessed an unusually highV max (442 μmol min−1mg−1) that was much higher than theV max of the same enzyme from another hyperthermophile, Methanococcus jannaschii. AlthoughT. maritima is a eubacterium, its I-1-Pase is more similar to archaeal I-1-Pases than to the other known bacterial or mammalian I-1-Pases with respect to substrate specificity, Li+inhibition, inhibition by high Mg2+ concentrations, metal ion activation, heat stability, and activation energy. Possible reasons for the observed kinetic differences are discussed based on an active site sequence alignment of the human and T. maritimaI-1-Pases.

RNA-cleaving 10–23 deoxyribozyme with a single amino acid-like functionality operates without metal ion cofactors

2010 ◽  
Vol 34 (5) ◽  
pp. 934 ◽  
Author(s):  
Damian Smuga ◽  
Kinga Majchrzak ◽  
Elzbieta Sochacka ◽  
Barbara Nawrot
Keyword(s):  
Amino Acid ◽  
Metal Ion ◽  
Single Amino Acid ◽  
Metal Ion Cofactors

Gold Cluster Crystals

2000 ◽  
Vol 6 (S2) ◽  
pp. 326-327
Author(s):  
J.F. Hainfeld ◽  
R.D. Powell ◽  
F.R. Furuya ◽  
J.S. Wall
Keyword(s):  
Metal Ion ◽  
Gold Cluster ◽  
Gel Filtration ◽  
Size Variation ◽  
Gold Clusters ◽  
Cluster Compounds ◽  
Statistical Process ◽  
3 Dimensional ◽  
X Ray Crystallography ◽  
Gold Compounds

Gold clusters are gold compounds with a core of gold atoms and organic groups covalently bound to the surface gold atoms. An example is undecagold, Au11(P(C6H5)3)7, whose structure was solved by x-ray crystallography using 3-dimensional crystals. These differ from colloidal gold, which are suspensions of metal particles, usually formed by metal ion reduction; although the particles may be approximately the same size, they vary due to the statistical process of formation. Gold clusters are compounds with a definite formula, and should all be perfectly identical. However, it is known that there is a family of stable gold cluster compounds, such as Au6, Au11, Au13, AU55, Au67, etc. In a given preparation of gold clusters, there is usually some mixture of these, thus leading to some size variation. Methods such as gel filtration column chromatography and ultrafiltration can be used to separate most of these species, so that relatively pure preparations may be achieved.

scholarly journals Kinetic characterization of enzyme forms involved in metal ion activation and inhibition of myo-inositol monophosphatase

1995 ◽  
Vol 307 (2) ◽  
pp. 585-593 ◽  
Author(s):  
F Strasser ◽  
P D Pelton ◽  
A J Ganzhorn
Keyword(s):  
Metal Ions ◽  
Metal Ion ◽  
Catalytic Mechanism ◽  
Inositol Monophosphatase ◽  
Inositol 1 ◽  
Enzyme Substrate ◽  
Nitrophenyl Phosphate ◽  
Preferential Binding ◽  
Sugar Phosphates ◽  
High Concentrations

Activation and inhibition of recombinant bovine myo-inositol monophosphatase by metal ions was studied with two substrates, D,L-inositol 1-phosphate and 4-nitrophenyl phosphate. Mg2+ and Co2+ are essential activators of both reactions. At high concentrations, they inhibit hydrolysis of inositol 1-phosphate, but not 4-nitrophenyl phosphate. Mg2+ is highly selective for inositol 1-phosphate (kcat. = 26 s-1) compared with the aromatic substrate (kcat. = 1 s-1), and follows sigmoid activation kinetics in both cases. Co2+ catalyses the two reactions at similar rates (kcat. = 4 s-1), but shows sigmoid activation only with the natural substrate. Li+ and Ca2+ are uncompetitive inhibitors with respect to inositol 1-phosphate, but non-competitive with respect to 4-nitrophenyl phosphate. Both metal ions are competitive inhibitors with respect to Mg2+ with 4-nitrophenyl phosphate as the substrate. With inositol 1-phosphate, Ca2+ is competitive and Li+ non-competitive with respect to Mg2+. Multiple inhibition studies indicate that Li+ and Pi can bind simultaneously, whereas no such complex was detected with Ca2+ and Pi. Several sugar phosphates were also characterized as substrates of myo-inositol monophosphatase. D-Ribose 5-phosphate is slowly hydrolysed (kcat. = 3 s-1), but inhibition by Li+ is very efficient (Ki = 0.15 mM), non-competitive with respect to the substrate and competitive with respect to Mg2+. Depending on the nature of the substrate, Li+ inhibits by preferential binding to free enzyme (E), the enzyme-substrate (E.S) or the enzyme-phosphate (E.Pi) complex. Ca2+, on the other hand, inhibits by binding to E and E.S, in competition with Mg2+. The results are discussed in terms of a catalytic mechanism involving two metal ions.

Using enzymes isolated from diverse sources to determine metal ion cofactors

2005 ◽  
Vol 381 (7) ◽  
pp. 1328-1335 ◽  
Author(s):  
Tatyana N. Shekhovtsova ◽  
Svetlana V. Muginova
Keyword(s):  
Metal Ion ◽  
Metal Ion Cofactors

scholarly journals 3-dimensional electrode patterning within a microfluidic channel using metal ion implantation

Lab on a Chip ◽  
2010 ◽  
Vol 10 (6) ◽  
pp. 783 ◽  
Author(s):  
Jae-Woo Choi ◽  
Samuel Rosset ◽  
Muhamed Niklaus ◽  
James R. Adleman ◽  
Herbert Shea ◽  
...  
Keyword(s):  
Ion Implantation ◽  
Metal Ion ◽  
Microfluidic Channel ◽  
3 Dimensional ◽  
Metal Ion Implantation
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