An extremely acidic copper-containing protein from chromaffin granules

Grigoryan, N. A.; Nalbandyan, R.M.; Buniatian, H. Ch.

doi:10.1016/0006-291x(81)91911-2

Cited by 11 publications

(3 citation statements)

References 13 publications

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“…Thus, either some mechanism must exist to protect the enzyme from inactivation (high levels of catalase) or a separate system for active reconstitution of DBH must be present. It is interesting in this connection to mention the discovery of a small acidic non-blue protein, neurocuproin, that appears to be present in catecholamine storage vesicles of both adrenal medullae and adrenergic neurons (Grigoryan et al, 1981;Sharoyan et al, 1977), which may be a possible candidate for copper transfer to DBH. Of particular significance is the finding that aponeurocuproin is able to inhibit DBH activity, presumably by a mechanism related to copper chelation, and regulation of DBH activity has been suggested as a possible physiological role for the holoneurocuproin molecule (Markossian et al, 1986).…”

Section: Discussionmentioning

confidence: 99%

Active site of dopamine .beta.-hydroxylase. Comparison of enzyme derivatives containing four and eight copper atoms per tetramer using potentiometry and EPR spectroscopy

et al. 1988

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Potentiometric titrations, continuous wave EPR, and microwave power saturation measurements have been used to examine 8-Cu and 4-Cu forms of native dopamine beta-hydroxylase and its azide derivative. The formation curve for the binding of Cu2+ to the apoenzyme is best fit by assuming two independent binding sites per subunit, with pK' values of 8.90 and 7.35 at pH 5.0. On the other hand, only minor differences are observed in either continuous wave EPR spectra or power saturation behavior of the 8- and 4-Cu forms of the native enzyme or of its azide derivative. The intensity of the EPR spectra of all derivatives integrates to greater than 95% of the total copper, and the temperature dependence of P1/2 shows no evidence for any S = 1 state of the copper ions in the enzyme. These results suggest a lower limit of ca. 7 A for the separation between the two copper ions per subunit and thus rule out a type 3 site in the oxidized enzyme. The data are most consistent with Cu(II) sites consisting of two or three N (imidazole) and one or two O donor ligands in the coordination sphere. The similarity in EPR spectra and power saturation of 8- and 4-Cu derivatives suggests that the difference in Cu-binding constants may be due either to differences in the identity of an axial ligand or to solvation effects in the active site.

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Section: Discussionmentioning

confidence: 99%

Active site of dopamine .beta.-hydroxylase. Comparison of enzyme derivatives containing four and eight copper atoms per tetramer using potentiometry and EPR spectroscopy

et al. 1988

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“…Mr, (PM30) = A . M r , (PMIo)-10,000 (A -IOO)/IOO, assuming that the molecules > 10 kD < 30 kD had Mr,n = 10,000(Grigoryan et a/. 1981).…”

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confidence: 99%

Osmotic properties of the chromogranins and relation to osmotic pressure in catecholamine storage granules

Helle

Reed

Pihl

et al. 1985

Acta Physiologica Scandinavica

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The soluble proteins (chromogranins) of bovine chromaffin granules have been studied by micro-osmometry with semi-permeable membranes (UM2, PM10 and PM30 with cut-offs greater than 1, greater than 10 and greater than 30 kD, respectively) at 1 = 0.15 and pH 5-8 for protein concentrations up to 20 mg X ml-1. After lysis of chromaffin granules in phosphate buffer pH 6, the released chromogranins behaved as aggregating solutes, consistent with an inconspicuous osmotic pressure contribution from the chromogranins at the protein concentration of the intact granules. Thus, in the presence of phosphate about 90% of the molecules behaved as colloids with Mr = 30,300 at c = o. After lysis in phosphate-free buffers the chromogranins behaved as highly non-ideal solutes in a manner which was incompatible with isotonicity at the protein concentration of the intact granules. About two-thirds of the molecules in the lysates in Na-succinate pH 5-6 and K-acetate pH 6 exhibited Mr = 66,000 and 79,000, respectively. In dilute solutions (less than 12 mg protein X ml-1) and ATP/protein ratios corresponding to those in the intact granules, the UM2 pressures were markedly increased, indicating release of polypeptides with Mr 2000-3000 from aggregates. CaCl2 was without specific effect on the colloid osmotic pressures but reduced the ATP-dependent increase in pressure, suggesting release of molecules twice the size of those released by ATP alone. A model is presented for the contribution of the chromogranins to osmotic pressure regulation in the bovine adrenomedullary catecholamine-storing granules.

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“…The first involves reduction of semidehydroascorbate (SDA •− ) in the granule matrix by cytochrome b 561 ( Cyt b 561 ), with the resulting ascorbate (AH − ) serving as a direct reductant of dopamine β‐hydroxylase. The second, represented by a dashed line , represents an alternative electron transfer pathway from cytochrome b 561 to dopamine β‐hydroxylase via a mediator protein (such as extremely acidic copper protein10). The heme composition of cytochrome b561 shown in the figure reflects our provisional hypothesis, with three hemes in a dimer of cytochrome b 561 , as discussed in the text.…”

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Composition of the Heme Centers in Chromaffin Granule Cytochrome b₅₆₁

Kamensky

Kulmacz

Palmer

2002

Annals of the New York Academy of Sciences

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An extremely acidic copper-containing protein from chromaffin granules

Cited by 11 publications

References 13 publications

Active site of dopamine .beta.-hydroxylase. Comparison of enzyme derivatives containing four and eight copper atoms per tetramer using potentiometry and EPR spectroscopy

Active site of dopamine .beta.-hydroxylase. Comparison of enzyme derivatives containing four and eight copper atoms per tetramer using potentiometry and EPR spectroscopy

Osmotic properties of the chromogranins and relation to osmotic pressure in catecholamine storage granules

Composition of the Heme Centers in Chromaffin Granule Cytochrome b₅₆₁

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An extremely acidic copper-containing protein from chromaffin granules

Cited by 11 publications

References 13 publications

Active site of dopamine .beta.-hydroxylase. Comparison of enzyme derivatives containing four and eight copper atoms per tetramer using potentiometry and EPR spectroscopy

Active site of dopamine .beta.-hydroxylase. Comparison of enzyme derivatives containing four and eight copper atoms per tetramer using potentiometry and EPR spectroscopy

Osmotic properties of the chromogranins and relation to osmotic pressure in catecholamine storage granules

Composition of the Heme Centers in Chromaffin Granule Cytochrome b561

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Composition of the Heme Centers in Chromaffin Granule Cytochrome b₅₆₁