Reactivity of M<sup>II</sup> Metal-Substituted Derivatives of Pig Purple Acid Phosphatase (Uteroferrin) with Phosphate

Twitchett, Mark B.; Schenk, Gerhard; Aquino, Manuel A.S.; Yiu, Douglas T. Y.; Lau, Tai‐Chu; Sykes, A. Geoffrey

doi:10.1021/ic020037f

Cited by 54 publications

(91 citation statements)

References 30 publications

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“…The assignment is consistent with spectroscopic studies of the interaction of phosphates with the bovine and pig enzymes [25,[27][28][29][30], which revealed an ionization occurring in the pH range 3.9-4.8. The conjugate base, a coordinated hydroxyl group, is a potential candidate for the attacking nucleophile in hydrolysis [25,[29][30][31]. The pK es2 value of $6 may correspond to a residue in the active site acting as a general acid to protonate the leaving group on hydrolysis.…”

Section: Resultssupporting

confidence: 87%

“…Fe III -Zn II and Fe III -Mn II derivatives of pig purple acid phosphatase (which mimic the binuclear centers in red kidney bean and sweet potato purple acid phosphatases, respectively [40,41]) were generated according to published procedures [20,30], and inhibition data were collected for both the OMTand the FOMT-containing tripeptides (Scheme 1) at pH 3.3 and 4.9. The results are summarized in Table 6.…”

Section: Inhibition Of Purple Acid Phosphatasesmentioning

confidence: 99%

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Phosphotyrosyl peptides and analogues as substrates and inhibitors of purple acid phosphatases

Valizadeh

Schenk

Nash

et al. 2004

Archives of Biochemistry and Biophysics

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Purple acid phosphatases are metal-containing hydrolases. While their precise biological role(s) is unknown, the mammalian enzyme has been linked in a variety of biological circumstances (e.g., osteoporosis) with increased bone resorption. Inhibition of the human enzyme is a possible strategy for the treatment of bone-resorptive diseases such as osteoporosis. Previously, we determined the crystal structure of pig purple acid phosphatase to 1.55 A and we showed that it is a good model for the human enzyme. Here, a study of the pH dependence of its kinetic parameters showed that the pig enzyme is most efficient at pH values similar to those encountered in the osteoclast resorptive space. Based on the observation that phosphotyrosine-containing peptides are good substrates for pig purple acid phosphatase, peptides containing a range of phosphotyrosine mimetics were synthesized. Kinetic analysis showed that they act as potent inhibitors of mammalian and plant purple acid phosphatases, with the best inhibitors exhibiting low micromolar inhibition constants at pH 3-5. These compounds are thus the most potent organic inhibitors yet reported for the purple acid phosphatases.

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Section: Resultssupporting

confidence: 87%

Section: Inhibition Of Purple Acid Phosphatasesmentioning

confidence: 99%

Phosphotyrosyl peptides and analogues as substrates and inhibitors of purple acid phosphatases

Valizadeh

Schenk

Nash

et al. 2004

Archives of Biochemistry and Biophysics

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“…For the Fe(III)Fe(III) form of uteroferrin an upper limit of less than 1% of the activity of the heterovalent form has been determined [16], the release of the ultimate reaction product (phosphate) being proposed as the likely candidate for the rate-limiting step in the PAP-catalyzed reaction [1,18,25,40]. This hypothesis finds support in the relative water exchange rates of Fe(III) and Fe(II) (10 2 and 10 6 s -1 , respectively) [41][42][43].…”

Section: Discussionmentioning

confidence: 99%

Phosphate ester cleavage promoted by a tetrameric iron(III) complex

et al. 2010

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The purple acid phosphatases (PAPs) are the only binuclear metallohydrolases where the necessity for a heterovalent active site [Fe(III)-M(II) (M is Fe, Zn or Mn)] for catalysis has been established. The paradigm for the construction of PAP biomimetics, both structural and functional, is that the ligands possess characteristics which mimic those of the donor sites of the metalloenzyme and permit discrimination between trivalent and divalent metal ions. The donor atom set of the ligand 2-((2-hydroxy-5-methyl-3-((pyridin-2-ylmethylamino)methyl)benzyl) (2-hydroxybenzyl)amino)acetic acid (H 3 HPBA) mimics that of the active site of PAP although the iron(III) complex of this ligand has been characterized as the tetramer [Fe 4 (HPBA) 2 (l-CH 3 COO) 2 (l-O)(l-OH)(OH 2 ) 2 ]ClO 4 Á5H 2 O. The phosphoesterase-like activity of the complex in 1:1 acetonitrile/water has now been investigated using the substrate 2,4-bis(dinitrophenyl)phosphate. The pH dependence of the catalytic rate revealed a non-symmetric bellshaped profile, with a finite but non-zero rate at high pH. Unlike the traditional approach usually employed to analyse these bell-shaped profiles, the approach used here involved incorporating additional species which contribute to the overall activity. Employing this approach, we show that the complex has a k cat of 1.6 (±0.2) 9 10 -3 s -1 , three kinetically relevant pK a values of 5.3, 6.2 and 8.4, with K M of 7.4 ± 0.6 mM. The kinetic parameters are similar to those reported for heterovalent PAP biomimetics. Additionally, it is observed that, unlike the enzyme, the oxidation state is not the determining factor for catalytic activity.

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“…16,17 In fact, this approach has been successfully employed to generate metalloderivatives of PAPs. [16][17][18][19][20][21][22][23] For instance, the Fe II in pig PAP (uteroferrin) can be replaced by Zn II without a significant change in activity, whereas the Mn II , Ni II , Cu II , and Co II derivatives display 10-50% activity of the native enzyme. 19,[21][22][23] Although the divalent ion can be replaced, there are no reports of catalytically active dinuclear homodivalent PAPs.…”

Section: Introductionmentioning

confidence: 99%

Metal-Ion Mutagenesis: Conversion of a Purple Acid Phosphatase from Sweet Potato to a Neutral Phosphatase with the Formation of an Unprecedented Catalytically Competent Mn^IIMn^II Active Site

et al. 2009

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Abstract:The currently accepted paradigm is that the purple acid phosphatases (PAPs) require a heterovalent, dinuclear metal-ion center for catalysis. It is believed that this is an essential feature for these enzymes in order for them to operate under acidic conditions. A PAP from sweet potato is unusual in that it appears to have a specific requirement for manganese, forming a unique Fe III -µ-(O)-Mn II center under catalytically optimal conditions (Schenk et al. Proc. Natl. Acad. Sci. U.S.A. 2005, 102, 273). Herein, we demonstrate, with detailed electron paramagnetic resonance (EPR) spectroscopic and kinetic studies, that in this enzyme the chromophoric Fe III can be replaced by Mn II , forming a catalytically active, unprecedented antiferromagnetically coupled homodivalent Mn II -µ-(H)OH-µ-carboxylato-Mn II center in a PAP. However, although the enzyme is still active, it no longer functions as an acid phosphatase, having optimal activity at neutral pH. Thus, PAPs may have evolved from distantly related divalent dinuclear metallohydrolases that operate under pH neutral conditions by stabilization of a trivalent-divalent metal-ion core. The present Mn II -Mn II system models these distant relatives, and the results herein make a significant contribution to our understanding of the role of the chromophoric metal ion as an activator of the nucleophile. In addition, the detailed analysis of strain broadened EPR spectra from exchange-coupled dinuclear Mn II -Mn II centers described herein provides the basis for the full interpretation of the EPR spectra from other dinuclear Mn metalloenzymes.

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Reactivity of M^II Metal-Substituted Derivatives of Pig Purple Acid Phosphatase (Uteroferrin) with Phosphate

Abstract: The Fe II of the binuclear Fe II Fe III active site of pig purple acid phosphatase (uteroferrin)

Cited by 54 publications

References 30 publications

Phosphotyrosyl peptides and analogues as substrates and inhibitors of purple acid phosphatases

Phosphotyrosyl peptides and analogues as substrates and inhibitors of purple acid phosphatases

Phosphate ester cleavage promoted by a tetrameric iron(III) complex

Metal-Ion Mutagenesis: Conversion of a Purple Acid Phosphatase from Sweet Potato to a Neutral Phosphatase with the Formation of an Unprecedented Catalytically Competent Mn^IIMn^II Active Site

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Reactivity of MII Metal-Substituted Derivatives of Pig Purple Acid Phosphatase (Uteroferrin) with Phosphate

Abstract: The Fe II of the binuclear Fe II Fe III active site of pig purple acid phosphatase (uteroferrin)

Cited by 54 publications

References 30 publications

Phosphotyrosyl peptides and analogues as substrates and inhibitors of purple acid phosphatases

Phosphotyrosyl peptides and analogues as substrates and inhibitors of purple acid phosphatases

Phosphate ester cleavage promoted by a tetrameric iron(III) complex

Metal-Ion Mutagenesis: Conversion of a Purple Acid Phosphatase from Sweet Potato to a Neutral Phosphatase with the Formation of an Unprecedented Catalytically Competent MnIIMnII Active Site

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Product

Resources

About

Reactivity of M^II Metal-Substituted Derivatives of Pig Purple Acid Phosphatase (Uteroferrin) with Phosphate

Metal-Ion Mutagenesis: Conversion of a Purple Acid Phosphatase from Sweet Potato to a Neutral Phosphatase with the Formation of an Unprecedented Catalytically Competent Mn^IIMn^II Active Site