Leucine Aminopeptidase (Bovine Lens)

Carpenter, Frederick H.; Vahl, James M.

doi:10.1016/s0021-9258(19)44474-8

Cited by 152 publications

(51 citation statements)

References 36 publications

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“…Even though zinc is an intrinsic component, in the absence of either Mn2+ or Mg2+ the enzyme is essentially inactive. Though the specific role of metals may differ in the various enzymes, a number of enzymes have similar dual requirements for Zn on the one hand and Mg and Mn on the other, e.g., E. coli DNA and RNA polymerases, alkaline phosphatases, and leucine aminopeptidase (Lehman et al, 1958;Chamberlain and Berg, 1962;Plocke et al, 1962;Simpson et al, 1968;Himmelhoch, 1969;Slater et al, 1971;Scrutton et al, 1971;Carpenter and Vahl, 1973;Anderson et al, 1975;. In zinc alkaline phosphatase, magnesium regulates the mode of binding of zinc and enhances the enzyme activity (Anderson et al, 1975).…”

Section: Discussionmentioning

confidence: 99%

Euglena gracilis DNA dependent RNA polymerase II: a zinc metalloenzyme

Falchuk¹,

Mazuś²,

Ulpino³

et al. 1976

Biochemistry

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Zinc is essential for cellular proliferation. Zinc deficiency of Euglena gracilis results in arrest of cell division and deranges nucleic acid and protein metabolism pointing to a decisive role of zinc in transcription and translation. We have, therefore, investigated the role of zinc in the function of the DNA-dependent RNA polymerases of this organism. Two RNA polymerases from zinc sufficient organisms were purified first by affinity chromatography on a DNA cellulose column and subsequently separated on diethylaminoethyl (DEAE)-Sephadex A-25. The two fractions were characterized as polymerase I and II by their elution pattern from DEAE-Sephadex and sensitivity to alpha-amanitin. RNA polymerase II has a provisional molecular weight of 700 000 and contains an average of 2.2 g=atoms of zinc per mol of enzyme, but not Mn, Cu, or Fe, as measured by microwave emission spectroscopy. Chelating agents, such as 1,10-phenanthroline, 8-hydroxyquinoline, 8-hydroxyquinoline-5-sulfonic acid, and lomofungin, inhibit activity. In contrast, the nonchelating analogues, 1,7-and 4,7-phenanthroline, do not affect activity. Inhibition by 1,10-phenanthroline is instantaneous and fully reversible by dilution. 1,10-Phenanthroline also inhibits RNA polymerase I, suggesting a role of zinc in its function. The demonstration that RNA polymerase II is a zinc enzyme indicates the involvement of zinc in eukaryotic RNA synthesis and serves as a further basis for the definition of the role of this element in eukaryotic cell growth, division, and differentiation.

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Section: Discussionmentioning

confidence: 99%

Euglena gracilis DNA dependent RNA polymerase II: a zinc metalloenzyme

Falchuk¹,

Mazuś²,

Ulpino³

et al. 1976

Biochemistry

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“…It is similar in many ways to the aminopeptidase from bovine lens (Taylor et al, 1984a,b;Oettgen & Taylor, 1985) that has been studied more extensively. In particular, both aminopeptidases are hexameric and possess two metal binding sites per subunit (Carpenter & Vahl, 1973; Thompson & Carpenter, 1976a,b;Van Wart & Lin, 1981;Allen et al, 1983). The activity of both aminopeptidases is influenced by the identity of the metal ion that resides at each site (Carpenter & Vahl, 1973;Thompson & Carpenter, 1976a; Van Wart & Lin, 1981;Allen et al, 1983), and it is of interest to differentiate the role of the metal ion at these two binding sites in catalysis.…”

mentioning

confidence: 99%

“…After chromatographic purification, porcine kidney and bovine lens LAP contain one and two Zn(II) atoms per subunit, respectively (Carpenter & Vahl, 1973; Van Wart & Lin, 1981). Porcine kidney LAP also binds a second Zn(II) per subunit in the presence of excess Zn(II), but the association constant is too small to allow isolation of the enzyme containing both Zn(II) atoms.…”

mentioning

confidence: 99%

Steady-state kinetics of hydrolysis of dansyl-peptide substrates by leucine aminopeptidase

Lin¹,

Lin²,

Wart³

1988

Biochemistry

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Stopped-flow fluorescence experiments have been carried out at 23 degrees C to study the hydrolysis of Leu-Gly-NHNH-Dns [Dns = 5-(dimethylamino)naphthalene-1-sulfonyl] and Leu-Gly-NH(CH2)2NH-Dns by porcine kidney cytosol leucine aminopeptidase (LAP). Experiments have been performed with LAP species containing Mg(II), Mn(II), Ni(II), Cu(II), Zn(II), and no metal ion at the regulatory metal binding site. The fluorescence changes observed on hydrolysis of these dansyl substrates by LAP arise from changes in the concentration of substrate. Several kinetic relationships have been developed that allow the steady-state kinetic parameters for these reactions to be determined from the stopped-flow fluorescence traces. When any of the five metal ions are bound at the regulatory site, kcat and KM are both raised to approximately the same extent with the result that the maximum increase observed for kcat/KM is only approximately twofold. The effects of these metal ions on kcat, KM, and kcat/KM observed for these substrates differ markedly from those for less physiologically relevant substrates, such as Leu-p-nitroanilide, that do not have amino acids on both sides of the scissile bond. This suggests that earlier conclusions regarding the effect of the regulatory metal ion on the activity of LAP may have been misleading and casts doubt as to whether the term "regulatory site" has validity in the context of LAP-catalyzed reactions under physiological conditions.

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“…Most aminopeptidases contain an intrinsic catalytic-essential zinc ion [11][12][13][14][15]. Addition of different metal ions to a second metal-binding site or formation of hybrids of metal ions on both binding sites modify the enzyme activity to various extents [16][17][18].…”

Section: Discussionmentioning

confidence: 99%

Effects of metal ions on the catalytic and thermodynamic properties of the aminopeptidase isolated from pronase

Lin

1995

Journal of Inorganic Biochemistry

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Leucine Aminopeptidase (Bovine Lens)

Cited by 152 publications

References 36 publications

Euglena gracilis DNA dependent RNA polymerase II: a zinc metalloenzyme

Euglena gracilis DNA dependent RNA polymerase II: a zinc metalloenzyme

Steady-state kinetics of hydrolysis of dansyl-peptide substrates by leucine aminopeptidase

Effects of metal ions on the catalytic and thermodynamic properties of the aminopeptidase isolated from pronase

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