scholarly journals Activation and inhibition of rabbit muscle pyruvate kinase by transition-metal ions

1975 ◽  
Vol 145 (1) ◽  
pp. 63-71 ◽  
Author(s):  
S Ainsworth ◽  
N Macfarlane
Keyword(s):  
Transition Metal ◽  
Comparative Study ◽  
Metal Ions ◽  
Pyruvate Kinase ◽  
Transition Metal Ions ◽  
Kinetic Constants ◽  
Ion Concentration ◽  
Rabbit Muscle ◽  
Bivalent Cation ◽  
Muscle Pyruvate Kinase

The paper reports a comparative study of the effects of Mn2+, Ni2+ and Co2+ on the reaction of ADP with phosphoenolypyruvate when catalysed by K+-activated rabbit muscle pyruvate kinase. The activation and subsequent inhibition that occurs as the bivalent ion concentration is increased is taken as evidence that the substrates of the enzyme are phosphoenolypyruvate, uncomplexed ADP and free bivalent cation. Kinetic constants for the binding of the bivalent cation to the enzyme are reported.

Chemical and enzymatic characterization of recombinant rabbit muscle pyruvate kinase

2013 ◽  
Vol 394 (5) ◽  
pp. 695-701 ◽  
Author(s):  
Christian Boehme ◽  
Frank Bieber ◽  
Julia Linnemann ◽  
Reinhard Breitling ◽  
Stefan Lorkowski ◽  
...  
Keyword(s):  
Metal Ions ◽  
Pyruvate Kinase ◽  
Adenosine Diphosphate ◽  
Transition Metal Ions ◽  
Recombinant Enzyme ◽  
High Yield ◽  
Rabbit Muscle ◽  
Reading Frame ◽  
Ph Range ◽  
Muscle Pyruvate Kinase

Abstract The stepwise synthesis of thymidine triphosphate (TTP) requires a kinase for phosphorylation in the last step. Because pyruvate kinase (PK) using phosphoenolpyruvate (PEP) as substrate can regenerate adenosine triphosphate and phosphorylate thymidine diphosphate as well, we chose this enzyme for the synthesis of TTP via an enzymatic cascade reaction. The metalloenzyme PK shows pronounced promiscuity and therefore fits well to the conditions of this reaction. PK commonly used today is isolated from rabbit muscle. We cloned and expressed the respective open reading frame in Escherichia coli, purified, and characterized the His-tagged recombinant enzyme. The enzyme has an activity optimum at 37°C and in the pH range from 7.4 to 7.8. Km constants conformed well with the isolated native enzyme for adenosine diphosphate (ADP) to 0.37±0.02 mm and for PEP to 0.07±0.01 mm. The recombinant enzyme shows the following range in its substrate specificity: ADP>dADP>dGDP>dCDP>thymidine diphosphate (TDP). It allows the phosphorylation of TDP to TTP in high yield (up to 95%). The metal ions Mg2+ and K+ are necessary for full enzymatic activity. The addition of transition metal ions such as Mn2+, Cu2+, Co2+, and Ni2+ reduces activity. Storage of the enzyme at -20°C retains full activity.

Behavior of Polyelectrolyte Gels in Concentrated Solutions of Highly Soluble Salts

MRS Advances ◽  
2020 ◽  
Vol 5 (17) ◽  
pp. 907-915 ◽  
Author(s):  
Jessica L. Sargent ◽  
Xunkai Chen ◽  
Mitchell C. Brezina ◽  
Sebastian Aldwin ◽  
John A. Howarter ◽  
...  
Keyword(s):  
Transition Metal ◽  
Metal Ions ◽  
High Performance Concrete ◽  
Group Versus ◽  
Transition Metal Ions ◽  
Main Group ◽  
Ion Concentration ◽  
Polyelectrolyte Gels ◽  
Counter Ion ◽  
Versus Transition

ABSTRACTIonic hydrogels are an abundant class of materials with applications ranging from drug delivery devices to high performance concrete to baby diapers. A more thorough understanding of interactions between polyelectrolyte networks and ionic solutes is critical as these materials are further tailored for performance applications in highly targeted ionic environments. In this work, we seek to develop structure-property relationships between polyelectrolyte gels and environments containing high concentrations of multivalent ions. Specifically, this work seeks to elucidate the causes behind differences in hydrogel response to divalent ions of main group metals versus transition metals. PANa-co-PAM hydrogels containing low and high fractions of ionic groups are investigated in solutions of DI water, NaCl, CaCl2, and CuSO4 at concentrations ranging from 5 to 100 mM in order to understand 1) the transient or permanent nature of crosslinks produced in these networks by divalent counter-ions, 2) the role of polymer ionic content in these interactions, and 3) how these interactions scale with salt concentration. Gravimetric swelling and mechanical compression testing are employed to characterize water and salt-swollen hydrogels in order to develop guiding principles to control and manipulate material properties through polymer-counter-ion interactions. The work presented here confirms the formation of permanent crosslinks by transition metal ions, offers explanation for the behavioral discrepancy observed between ionic hydrogels and main group versus transition metal ions, and illustrates how such hydrogel properties scale with counter-ion concentration.

scholarly journals Metallo-Supramolecular Hydrogels from the Copolymers of Acrylic Acid and 4-(2,2′:6′,2″-terpyridin-4′-yl)styrene

Polymers ◽  
2019 ◽  
Vol 11 (7) ◽  
pp. 1152 ◽  
Author(s):  
Huiqin Zhang ◽  
Pan Liu ◽  
Zheng Chi ◽  
Xuegang Chen
Keyword(s):  
Transition Metal ◽  
Acrylic Acid ◽  
Metal Ions ◽  
Self Assembly ◽  
Wavelength Region ◽  
Transition Metal Ions ◽  
Ion Concentration ◽  
Iron Ions ◽  
Absorption Intensity ◽  
Dilute Aqueous Solution

Hydrophilic copolymers containing 2,2′:6′,2″-terpyridine moieties and acrylic acid (AA) units poly (acrylic acid-co-4-(2,2′:6′,2″-terpyridin-4′-yl)styrene) (P(AA-co-TPY)) were synthesized and characterized. Coordinated with different transition metal ions, the dilute aqueous solution of the copolymers exhibited red-shifted UV-vis absorption peaks of π-π* transition from 317 to 340 nm. Further, interacting with iron ions, the copolymer showed new absorption peaks at a longer wavelength region (570 nm) and the absorption intensity enhanced with increase of the ion concentration. When enough ions were added to coordinate with the 2,2′:6′,2″-terpyridine moieties, novel metallo-supramolecular hydrogels were obtained due to the formation of metal coordination bonds between polymer back bones and transition metal ions (Ni2+, Zn2+, Cd2+, Fe2+ and Cu2+), which acted as self-assembly crosslinking structures. The mechanical strength and morphology of the resulting metallo-supramolecular hydrogels have been investigated.

pH-Dependent amino acid induced conformational changes of rabbit muscle pyruvate kinase

1980 ◽  
Vol 58 (3) ◽  
pp. 188-193 ◽  
Author(s):  
Chiu-Yin Kwan ◽  
Robert C. Davis
Keyword(s):  
Metal Ions ◽  
Pyruvate Kinase ◽  
Conformational Changes ◽  
Divalent Metal ◽  
Rabbit Muscle ◽  
Divalent Metal Ions ◽  
Spectral Changes ◽  
Metal Derivatives ◽  
Muscle Pyruvate Kinase ◽  
Difference Absorption

The interactions of L-Phe and L-Ala with rabbit muscle pyruvate kinase depended upon the nature of divalent metal ions studied: Mg(II), Co(II), Mn(II), and Ni(II). L-Phe inhibited all metal derivatives of the enzyme except Mn(II)–enzyme. L-Ala inhibited only Ni(II)–enzyme and had no effect on other metal derivatives. The inhibition by L-Phe could be partially or completely reversed by L-Ala for all metal derivatives. The mode of inhibition of pyruvate kinase by L-Phe depended upon pH as well as the nature of activating divalent metal ions. The sigmoidal response increased with increasing pH for all metal derivatives inhibited by L-Phe. L-Phe and L-Ala strongly perturbed the coordination sphere of enzyme bound Co(II), but not Ni(II). There were poor correlations between visible circular dichroic (cd) spectral changes and the corresponding kinetic changes. However, L-Phe and (or) L-Ala induced ultraviolet cd and difference absorption spectral changes, on the other hand, corresponded remarkably well with the kinetic observations.

scholarly journals Electrocatalysis by crown-type polyoxometalates multi-substituted by transition metal ions; Comparative study

2015 ◽  
Vol 176 ◽  
pp. 1248-1255 ◽  
Author(s):  
Rashda Naseer ◽  
Sib Sankar Mal ◽  
Ulrich Kortz ◽  
Gordon Armstrong ◽  
Fathima Laffir ◽  
...  
Keyword(s):  
Transition Metal ◽  
Comparative Study ◽  
Metal Ions ◽  
Transition Metal Ions

L-Phenylalanine induced changes of sulfhydryl reactivity in rabbit muscle pyruvate kinase

1981 ◽  
Vol 59 (2) ◽  
pp. 92-99 ◽  
Author(s):  
Chiu-Yin Kwan ◽  
Robert C. Davis
Keyword(s):  
Metal Ions ◽  
Pyruvate Kinase ◽  
Divalent Metal ◽  
Enzyme Inactivation ◽  
Rabbit Muscle ◽  
Divalent Metal Ions ◽  
Substrate Analogue ◽  
Metal Derivatives ◽  
Sulfhydryl Modification ◽  
Muscle Pyruvate Kinase

Reactivity of sulfhydryl groups in rabbit muscle pyruvate kinase toward 5,5′-dithiobis(2-nitrobenzoic acid) (DTNB) was studied in the presence of activating divalent metal ions, substrate, substrate analogue, and the allosteric inhibitor, L-Phe. The pattern of sulfhydryl modification in various complexes of pyruvate kinase was consistent with the extent of enzyme inactivation by DTNB under very similar conditions. The sulfhydryl reactivity of Mg(II)-, Co(II)-, and Mn(II)-substituted pyruvate kinase toward DTNB depended upon the nature of the activating divalent metal ions used in the following order of increasing potency, Mg(II) < Mn(II) < Co(II), which is inversely related to the order of catalytic efficiency of these metal ions at alkaline pH. Similar optical spectra and the patterns of sulfhydryl modification by DTNB of the metal derivatives of pyruvate kinase were observed upon the binding of the substrate, phosphoenolpyruvate (PEP), or the substrate analogue, phosphoglycolate, which also provided a complete protection against enzyme inactivation by DTNB. L-Phe, on the other hand, deprotected the enzyme from inactivation and further sulfhydryl modification by DTNB in the presence of PEP with the following order of potency depending upon the activating metal ions, Mn(II) < Co(II) < Mg(II), which parallels the order of metal dependency of L-Phe inhibition of this enzyme. L-Ala, which reverses the L-Phe inhibition of Mg(II)- or Co(II)-activated enzyme, restored the protective effect of PEP in the presence of L-Phe. The different patterns of sulfhydryl reactivity toward Mn(II)–enzyme (hyperbolic) and Mg(II)–enzyme (sigmoidal) correspond well with their kinetic patterns in the presence of L-Phe, indicating the presence of different conformational states between these two metal–enzyme complexes. These results led us to conclude that enzyme sulfhydryl reactivity toward DTNB can be used as a valid index for allosteric conformational changes of rabbit muscle pyruvate kinase.

scholarly journals Selective Chromogenic Recognition of Copper(II) Ion by Thiacalix[4]arene Tetrasulfonate and Mechanism

Molecules ◽  
2020 ◽  
Vol 25 (3) ◽  
pp. 612 ◽  
Author(s):  
Shufang Zhu ◽  
Lilin Lu
Keyword(s):  
Transition Metal ◽  
Metal Ions ◽  
Density Functional ◽  
Color Change ◽  
Bathochromic Shift ◽  
Transition Metal Ions ◽  
Water Soluble ◽  
Ion Concentration ◽  
Absorption Bands ◽  
Simple Method

Detection of biologically important transition metal ions such as copper by using a simple method is desirable and of great importance. In this work, we firstly reported that water-soluble thiacalix[4]arene tetrasulfonate (TCAS) exhibited selective chromogenic recognition towards copper(II) ion over other transition metal ions. Color change from colorless to salmon pink was observed in TCAS solution, weak bathochromic shift was induced in UV absorption spectrum of TCAS upon addition of copper(II) ion, and the absorbance of characteristic absorption band at 312 nm increased linearly with copper(II) ion concentration. The recognition mechanism of TCAS to copper(II) ion was investigated by a comparative study with calix[4]arene tetrasulfonate (CAS) and time-dependent density functional theory(TD-DFT) study, and the absorption bands were assigned based on transition orbital analysis.

Comparative study of the magnetic form factors of transition-metal ions

1981 ◽  
Vol 23 (6) ◽  
pp. 2697-2709 ◽  
Author(s):  
D. C. Khan ◽  
S. M. Kirtane ◽  
J. K. Sharma
Keyword(s):  
Transition Metal ◽  
Comparative Study ◽  
Metal Ions ◽  
Form Factors ◽  
Transition Metal Ions ◽  
Magnetic Form Factors
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