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Ca2+
-
about 80% reactivation of the demetalled protein
Cu2+
-
inhibits enzymatic activity. High molecular weight fraction as well as metallothionein are involved in the detoxification of harmful heavy metals
Cd2+
-
can restore activity of the apoenzyme
Cd2+
-
inhibition at low concentration of substrate and stimulation at high levels of substrate
Cd2+
-
inhibits enzymatic activity. High molecular weight fraction as well as metallothionein are involved in the detoxification of harmful heavy metals
Co2+
-
activates
Co2+
-
about 50% reactivation of the demetalled protein
Co2+
-
partially restores activity after inhibition with EDTA
Co2+
-
about 70% reactivation of the demetalled protein
Fe2+
-
about 70% reactivation of the demetalled protein
Fe2+
-
partially restores enzyme after inactivation of 2,9-dimethyl-4,7-diphenyl-1,10-phenanthrolinedisulfonate
K+
-
required
K+
-
activates up to 3 mM
K+
-
stimulates, between pH 6.5 and 7.0, K+ is as stimulatory as Mg2+ and the stimulation is almost 2fold
Mg2+
-
enzyme utilizes a catalytic MgA present at a stoichiometry of 4/octamer, an allosteric MgC present at a stoichiometry of 8/octamer and a monovalent metal ion, K+
Mg2+
-
4 Zn at metal binding site A , 4 Zn at metal binding site B and 8 Mg at metal binding site C are required for full activity per homooctamer
Mg2+
-
Mg(II) causes a twofold stimulation of the Zn(II)-induced activity
Mg2+
-
can not activate the apoenzyme alone, but is able to substitute for the second molar equivalent of bound Zn2+ leading to a further 4fold stimulation
Mg2+
chimeric proteins are constructed that contain the aspartate-rich sequences of the pea enzyme or the enzyme from Pseudomonas aeruginosa in place of the naturally occuring cysteine-rich sequence of the human enzyme. The chimeric enzymes are substantially activated by both magnesium and potassium, but not by zinc
Mg2+
-
4 Zn at metal binding site A and 8 Mg at metal binding site C are required for full activity per homooctamer
Mg2+
-
essentail cofactor, allosteric Mg(II) binds with a Kd of 2.5 mM, 2.3fold activation, binding of 3 Mg(II) per subunit
Mg2+
-
2 Mg2+ binding sites per subunit
Mg2+
-
implicated in quarternary structure
Mg2+
-
20-30% stimulation at pH 8.5, no requirement for a metal ion
Mg2+
-
stimulates but is not required for activity. Eight Mg2+ ions can be seen in the crystal structure, one per monomer, all bound at the allosteric magnesium-binding site. No metal ion can be seen in the active site
Mg2+
-
binds only 4 Mg2+ per octamer, these 4 Mg2+ allosterically stimulate a metal ion independent catalytic actiovity, in a fashion dependent upon both pH and K+, the allosteric Mg2+ is located in metal binding site C, which is outside the active site. NO evidence is found for metal binding to the potential high-affinity active site metal binding site A and/or B, no direct involvement of Mg2+ in substrate binding and product formation
Mg2+
-
can completrly restore activity after inhibition by EDTA
Mg2+
-
can completrly restore activity after inhibition by EDTA, stabilizes the oligomeric state but is not essential for octamer formation
Mg2+
enzyme contains Mg2+ in the active site
Mg2+
-
enzyme responds to Mg2+ but not to Zn2+, enzyme shows two Mg2+ affinities
Mn2+
-
activates
Mn2+
-
can reactivate the demetallated protein
Mn2+
-
can reactivate the demetallated protein
Ni(2+)
-
0.15 mM, activates
Ni(2+)
-
about 70% reactivation of the demetalled protein
Ni2+
-
partially restores activity after inhibition with EDTA
Zinc
-
contains 1 gatom of zinc per mol of subunit, zinc has a structural rather than a direct catalytic role
Zinc
-
lacks a catalytic ZnA, enzyme can bind Zn(II), presumably as ZnA, at a stoichiometry of 4/octamer with a Kd of 0.2 mM, this high concentration is outside the physiologically significant range
Zinc
-
Zn(II) metalloenzyme, Zn(II) is required for catalytic activity
Zinc
-
4 Zn at metal binding site A , 4 Zn at metal binding site B and 8 Mg at metal binding site C are required for full activity per homooctamer
Zinc
-
4 Zn at metal binding site A and 4 Zn at metal binding site B are required for full activity per homooctamer
Zinc
-
binds 8 mol of zinc per mol of octamer, zinc may interact with one or more of the highly reactive enzyme thiol groups
Zinc
-
4 Zn at metal binding site A and 8 Mg at metal binding site C are required for full activity per homooctamer
Zinc
8 Zn at metal binding site A and 8 Zn at metal binding site B are required for full activity per homooctamer
Zn2+
-
required
Zn2+
-
Zn2+ forms a bond with a sulfhydryl group in the enzyme, the octameric enzyme contains 4 gatom of Zn2+ per mol of enzyme, Zn2+ does not participate in substrate binding nor in the maintenance of the quarternary structure of the enzyme
Zn2+
-
2 mol of Zn2+ bound per mol of subunit
Zn2+
enzyme uses a catalytic Zn2+
Zn2+
-
0.5 mM, 10% increase in activity
Zn2+
-
optimal activation by 0.1-0.3 mM ZnCl2
Zn2+
-
activates at 0.1-0.02 mM, inhibits at 1.0 mM
Zn2+
the cysteines of the metal switch sequence of the wild-type enzyme bind a catalytic zinc. Chimeric proteins are constructed that contain the aspartate-rich sequences of the pea enzyme or the enzyme from Pseudomonas aeruginosa in place of the naturally occuring cysteine-rich sequence of the human enzyme. The chimeric enzymes are substantially activated by both magnesium and potassium, but not by zinc.
Zn2+
-
optimal stimulation at 0.1 mM
Zn2+
-
required for activity
Zn2+
-
inhibits enzymatic activity
Zn2+
-
partially restores activity after inhibition with EDTA
Zn2+
requires exogenous thiols and zinc ions for optimal activity. 0.7 zinc ions per mol of subunit
Zn2+
-
delta-ALA-D is a metalloenzyme requiring zinc for activation
Zn2+
-
activity is progressively increased with increasing Zn2+ concentrations up to 0.1 mM, inhibition at high concentrations
Zn2+
-
required for catalysis, bound at the active site
Zn2+
-
restores enzyme after inactivation by 2,9-dimethyl-4,7-diphenyl-1,10-phenanthrolinedisulfonate
additional information
-
zinc is apparently not a cofactor
additional information
-
no stimulation by Mg2+
additional information
-
does not require metallic cations for activation
additional information
does not utilize metal ions such as Zn2+ or Mg2+
additional information
-
does not utilize metal ions such as Zn2+ or Mg2+