Primary structures of seven metallothioneins from rabbit tissue

Hunziker, Peter; Kaur, Parjit; Wan, Min; Kanzig, A.

doi:10.1042/bj3060265

Cited by 35 publications

(31 citation statements)

References 21 publications

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“…To date, six subisoforms of rabbit liver MT-I and MT-II isoforms have been reported [27] (Swiss-Prot Database, http://www.expasy.ch), which in some cases were also found as non-N-acetylated subisoforms. Table 1 shows their amino acidic sequences and, in bold letters, the relevant ionizable amino acids over the whole pH range.…”

Section: Determination Of Electrophoretic Mobility (M E ) Pk Values mentioning

confidence: 99%

Modeling the migration behavior of rabbit liver apothioneins in capillary electrophoresis

et al. 2008

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Metallothioneins (MTs) are a group of low-molecular-mass proteins (6-7 kDa) characterized by their great affinity for heavy metal ions. At acidic pH, the bound metal ions are released from the amino acidic structure and MTs lead to apothioneins. In this study, a general equation is used to model the electrophoretic mobility of rabbit liver apothioneins as a function of the pH of the separation electrolyte. The ability of these relationships to explain the migration behavior of these relatively complex polyprotic proteins in the pH range between 2 and 6 has been investigated. Their relevant ionization constant values in the studied pH range were estimated and employed for molecular charge calculations. The classical semiempirical relationships between electrophoretic mobility and charge-to-mass ratio (me vs. q/Malpha) were tested for prediction of their electrophoretic separations. The accuracy of the separations predicted at acidic pH was confirmed by CE-ESI-MS.

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Section: Determination Of Electrophoretic Mobility (M E ) Pk Values mentioning

confidence: 99%

Modeling the migration behavior of rabbit liver apothioneins in capillary electrophoresis

et al. 2008

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“…ESI-MS under acidic conditions showed that this MT-2 preparation consisted of roughly equivalent amounts of MT-2a and MT-2c (nomenclature of Ref. 33).…”

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confidence: 99%

Modulation of DNA Binding of a Tramtrack Zinc Finger Peptide by the Metallothionein-Thionein Conjugate Pair

Roesijadi¹,

Bogumil²,

Vašák³

et al. 1998

Journal of Biological Chemistry

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The ability of metallothionein (MT) to modulate DNA binding by a two-finger peptide of Tramtrack (TTK), a CCHH zinc transcription factor, was investigated using metal-bound and metal-deficient forms of rabbit MT-2 and the TTK peptide. Thionein inhibited DNA binding by zinc-bound TTK, and Zn-MT restored DNA-binding by zinc-deficient apo-TTK. "Free" zinc at low concentrations was as effective as Zn-MT in restoring DNA binding by apopeptide but was inhibitory at concentrations equal to zinc bound to 2 mol eq and higher of Zn-MT. Substitution of cadmium for zinc reduced the affinity of the peptide for its DNA binding site. This effect was reversed by incubation with Zn-MT. The circular dichroic spectra of the TTK peptide indicated that zinc removal resulted in loss of ␣-helical structures, which are sites of DNA contact points. Reconstitution with cadmium resulted in stoichiometric substitution of 2 mol of Cd/mol of peptide but not recovery of ␣-helical structures. Incubation of Cd-TTK with Zn-MT restored the secondary structure expected for zinc-bound TTK. The ability of Zn-MT and thionein to restore or inhibit DNAbinding by TTK was associated with effects on the metallation status of the peptide and related alterations in its secondary structure.The low molecular weight metal-binding protein metallothionein (MT) 1 is proposed to have functions in metal ion regulation and detoxification (1) and as a scavenger of free radicals (2). Roles for MT in dynamic intermolecular metal exchange reactions are consistent with the high thermodynamic stability (3) and high kinetic lability of its metal binding sites (4, 5). Metal exchange can also be facilitated by cellular redox couples such as ). An early focus on enzyme activation by Zn-MT implicated MT as a zinc donor to apometallic forms of metalloenzymes such as aldolase, thermolysin, and carbonic anhydrase (10) and pyridoxal kinase (11). Recent studies on the effect of MTs on interactions between zinc transcription factors and their cognate DNAs implicate MTs in gene regulation. Incubation of metal-free thionein with CCHH zinc finger transcription factors Sp1 (12) and TFIIIA (13) inhibits DNA binding, suggesting zinc abstraction by thionein as a mechanism for regulating gene expression. Reciprocal zinc exchange is suggested as a mechanism for regulating gene expression in a study in which Zn-MT and thionein could activate or inhibit DNA binding by the estrogen receptor (14), a CCCC zinc finger protein.Zinc transcription factors appear uniquely qualified as potential partner molecules in metal exchange reactions with MT. Reported stability constants for zinc binding by zinc finger peptides and proteins are in a similar range, i.e. within 1 or 2 orders of magnitude, as that of . Additionally, it appears that the kinetics for zinc exchange in these structures are also relatively rapid (18). Direct examination of the metal transfer process has shown that zinc can be transferred from an ␣-domain peptide of human MT-2 (␣-hMT-2) to a peptide derived from the third finger of Sp1...

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“…MT-1a, MT-2a, MT-2b, MT-2c, MT-2d and MT-2e [36] (Swiss-Prot Database, Electrophoresis 2008, 29, 4355-4367 http://www.expasy.ch). Their presence in MT-I, MT-II and MT samples was confirmed in our previous studies using LC-ESI-MS and CE-ESI-MS [6,37].…”

Section: Resultsmentioning

confidence: 99%

A multiway approach for classification and characterization of rabbit liver apothioneins by CE‐ESI‐MS

et al. 2008

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We applied a multiway approach to extract information from the analysis of protein isoforms by CE-ESI-MS. Metallothioneins (MT) are low-molecular-weight proteins (6-7 kDa) with a strong affinity for heavy-metal ions. Rabbit liver MT-I and MT-II fractions are purified from MT samples. At low pH, the bound metal ions were released from the amino acid structures, giving rise to apothioneins. MT-I, MT-II and MT apothioneins, which are complex mixtures of protein isoforms, were analyzed by CE-ESI-MS. After data pre-processing, parallel factor analysis (PARAFAC) and multivariate curve resolution-alternating least squares (MCR-ALS) were applied to the data sets. In both cases, the models enabled classification of the protein samples and identification of their characteristic sub-isoforms using a set of three components. MCR-ALS required an initial estimate of the pure mass spectra of the three components. Thus, PARAFAC loadings were used to initialize the MCR-ALS optimization. The classifications obtained with MCR-ALS were slightly better than those obtained with PARAFAC, probably because MCR-ALS was less affected by the small migration time shifts of the preprocessed electropherograms. However, no differences were found between the pure mass spectra of the three components in either model. Finally, MCR-ALS allowed us to obtain an individual electrophoretic profile of each of the three components for each of the samples analyzed, which proved valuable for characterization and quantification purposes.

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Primary structures of seven metallothioneins from rabbit tissue

Cited by 35 publications

References 21 publications

Modeling the migration behavior of rabbit liver apothioneins in capillary electrophoresis

Modeling the migration behavior of rabbit liver apothioneins in capillary electrophoresis

Modulation of DNA Binding of a Tramtrack Zinc Finger Peptide by the Metallothionein-Thionein Conjugate Pair

A multiway approach for classification and characterization of rabbit liver apothioneins by CE‐ESI‐MS

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