scholarly journals Influence of transition and heavy metal ions on ATP-ases activity in rat synaptic plasma membranes

2004 ◽  
Vol 69 (7) ◽  
pp. 541-547 ◽  
Author(s):  
Ljubica Vujisic ◽  
Danijela Krstic ◽  
Katarina Krinulovic ◽  
Vesna Vasic
Keyword(s):  
Heavy Metal ◽  
Metal Ions ◽  
Heavy Metal Ions ◽  
Plasma Membranes ◽  
Model System ◽  
Half Maximum ◽  
Synaptic Plasma Membranes ◽  
Equilibrium Binding ◽  
Inhibitory Activities ◽  
The Stability

The influence of transition metal (Cu2+, Zn2+, Fe2+ and Co2+) and heavy metal ions (Hg2+, Pb2+ and Cd2+) on the activities of Na+/K+-ATPase and Mg2+-ATPase isolated from rat synaptic plasma membranes (SPM) was investigated. The aim of the study was to elucidate the inhibition of both ATPase activities by exposure to the considered metal ions as a function of their affinity to bind to the ?SH containing ligand L-cysteine, as a model system. The half-maximum inhibitory activities (IC 50) of the enzymes were determined as parameters of rectangular hyperbolas and correlated with the stability constant (K s) of the respectivemetal- ion-L-cysteine complex. The linear Dixon plots indicate equilibrium binding of the investigated ions to both enzymes.

PREPARATION AND PROPERTIES OF TRANSKETOLASE FROM PORK LIVER

1960 ◽  
Vol 38 (1) ◽  
pp. 115-124 ◽  
Author(s):  
F. J. Simpson
Keyword(s):  
Heavy Metal ◽  
Metal Ions ◽  
Heavy Metal Ions ◽  
Thiamine Pyrophosphate ◽  
Magnesium Ions ◽  
Optimum Activity ◽  
Pork Liver ◽  
High Concentrations ◽  
The Stability ◽  
Ph Range

Transketolase of pork liver has been purified 90-fold and separated from ribulose 5-phosphate 3-epimerase. The transketolase is most stable between pH 7.5 and 8.5 and below 40 °C. The pH range for optimum activity is between 7.6 and 8.1. Activation by magnesium ions or thiamine pyrophosphate could not be demonstrated, but thiamine pyrophosphate increased the stability of the enzyme. Sulphydryl agents, such as p-chloromercuriphenyl sulphonic acid and N-ethylmaleimide, and heavy metal ions, such as cupric, mercuric, and zinc, at relatively high concentrations inhibited the enzyme.

scholarly journals Comparative study of binding strengths of heavy metals with humic acid

2013 ◽  
Vol 67 (5) ◽  
pp. 773-779 ◽  
Author(s):  
Ivana Kostic ◽  
Tatjana Andjelkovic ◽  
Ruzica Nikolic ◽  
Tatjana Cvetkovic ◽  
Dusica Pavlovic ◽  
...  
Keyword(s):  
Heavy Metals ◽  
Heavy Metal ◽  
Humic Acid ◽  
Metal Ions ◽  
Stability Constants ◽  
Metal Ion ◽  
Heavy Metal Ions ◽  
Exchange Method ◽  
Divalent Metal Ion ◽  
The Stability

The complexation of humic acid with certain heavy metal ions (Co(II), Ni(II), Cu(II), Zn(II) and Pb(II)) was investigated. The stability constants of humate complexes were determined by method which is based on distribution of metal ions between solution and resin in the presence and the absence of ligand, known as Schubert?s ion exchange method. Experiments were performed at 25 ?C, at pH 4.0 and ionic strength of 0.01 mol dm-3. It was found that the 1:1 complexes were formed between metal ions and humic acid. Obtained results of the stability constants, log ?mn, of complexes formed between the metal ions and humic acid follow the order Co(II) < Ni(II) < Cu(II) > Zn(II) which is the same like in the Irving-Williams series for the binding strength of divalent metal ion complexes. Stability constant of complex between Pb(II) ions and humic acid is greater than stability constants of other investigated metal-humate complexes. The investigation of interaction between heavy metal ions and humics is important for the prediction of the distribution and control of the migration of heavy metals in natural environment.

PREPARATION AND PROPERTIES OF TRANSKETOLASE FROM PORK LIVER

1960 ◽  
Vol 38 (2) ◽  
pp. 115-124 ◽  
Author(s):  
F. J. Simpson
Keyword(s):  
Heavy Metal ◽  
Metal Ions ◽  
Heavy Metal Ions ◽  
Thiamine Pyrophosphate ◽  
Magnesium Ions ◽  
Optimum Activity ◽  
Pork Liver ◽  
High Concentrations ◽  
The Stability ◽  
Ph Range

Transketolase of pork liver has been purified 90-fold and separated from ribulose 5-phosphate 3-epimerase. The transketolase is most stable between pH 7.5 and 8.5 and below 40 °C. The pH range for optimum activity is between 7.6 and 8.1. Activation by magnesium ions or thiamine pyrophosphate could not be demonstrated, but thiamine pyrophosphate increased the stability of the enzyme. Sulphydryl agents, such as p-chloromercuriphenyl sulphonic acid and N-ethylmaleimide, and heavy metal ions, such as cupric, mercuric, and zinc, at relatively high concentrations inhibited the enzyme.

scholarly journals Heavy metal complexation by surfaces and humic acids: a brief discourse on assessment by acidimetric titration.

1987 ◽  
Vol 35 (3) ◽  
pp. 231-240 ◽  
Author(s):  
Z.J. Wang ◽  
W. Stumm
Keyword(s):  
Heavy Metal ◽  
Metal Ions ◽  
Metal Ion ◽  
Heavy Metal Ions ◽  
Natural Waters ◽  
Ion Concentration ◽  
Natural Sample ◽  
Voltammetric Measurement ◽  
Ph Dependent ◽  
The Stability

In natural waters the form of occurrence of heavy metal ions needs to be known to understand the factors that control their concentrations, their reactivity and bioavailability. In natural samples, it is difficult to identify the species present and to distinguish between dissolved and particulate concentrations, because of the lack of sufficiently sensitive and specific analytical detectors. It is suggested that the voltammetric measurement of the labile metal ion concentration as a function of pH (from an acidimetric titration of a natural sample) may provide useful information on the pH-dependent distribution of soluble and particulate concentrations and on the stability of (surface and solute) complexes formed. (Abstract retrieved from CAB Abstracts by CABI’s permission)

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