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Purple acid phosphatases

About: Purple acid phosphatases is a research topic. Over the lifetime, 306 publications have been published within this topic receiving 13795 citations.


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TL;DR: To extend the biochemical characterization of wild-type phytases, the catalytic properties of a series of fungal phytased, as well as Escherichia coli phytase, were determined and phosphate liberation kinetics were studied in vitro.
Abstract: The phosphatases are a diverse class of enzymes. According to one classification, alkaline phosphatases, purple acid phosphatases, high-molecular-weight acid phosphatases, low-molecular-weight acid phosphatases, and protein phosphatases can be distinguished (13). These classes differ in their pH optima, metal ion requirements, substrate specificities, and possibly even reaction mechanisms. The phytases (myo-inositol hexakisphosphate phosphohydrolases; EC 3.1.3.8 and 3.1.3.26) are a subfamily of the high-molecular-weight histidine acid phosphatases. The phytase reaction mechanism is a two-step mechanism which includes a covalent phosphohistidine adduct as an obligatory reaction intermediate (6). Phytases are found naturally in plants and microorganisms, particularly fungi (for a review see reference 15). They catalyze phosphate monoester hydrolysis of phytic acid (myo-inositol hexakisphosphate), which results in the stepwise formation of myo-inositol pentakis-, tetrakis-, tris-, bis-, and monophosphates, as well as the liberation of inorganic phosphate. Phytic acid is the major storage form of phosphorus in plant seeds and, thus, in seed-based animal feed (for reviews see references 1 and 8). Monogastric animals, such as pigs and poultry, are not able to utilize phytic acid phosphorus, since they have only low levels of phytase activity in their digestive tracts and since phytic acid cannot be resorbed. Therefore, pig and poultry feed commonly is supplemented with either inorganic phosphate or a phytase of fungal origin. Despite considerable economic interest, only limited data on the catalytic properties of fungal phytases are available. In order to get an impression of the natural diversity of phytases, the enzymatic properties of six fungal phytases (phytases from Aspergillus niger, two strains of Aspergillus terreus, Aspergillus fumigatus, Emericella nidulans, and Myceliophthora thermophila) and of Escherichia coli phytase were characterized in more detail by addressing the following questions. (i) What are the specific activities and pH optima of wild-type phytases? (ii) What are the kinetics of phytic acid degradation, and what are the end products? (iii) Does the substrate specificity profile correlate with the results of in vitro experiments performed to determine phosphate liberation from feed samples? And (iv) what is the potential influence of modulators of enzymatic activity?

472 citations

Journal ArticleDOI
09 Jun 1995-Science
TL;DR: The active-site structure of the homodimeric 111-kilodalton KBPAP is consistent with previous proposals regarding the mechanism of phosphate ester hydrolysis involving nucleophilic attack on the phosphate group by an Fe(III)-coordinated hydroxide ion.
Abstract: Kidney bean purple acid phosphatase (KBPAP) is an Fe(III)-Zn(II) metalloenzyme resembling the mammalian Fe(III)-Fe(II) purple acid phosphatases. The structure of the homodimeric 111-kilodalton KBPAP was determined at a resolution of 2.9 angstroms. The enzyme contains two domains in each subunit. The active site is located in the carboxyl-terminal domain at the carboxy end of two sandwiched beta alpha beta alpha beta motifs. The two metal ions are 3.1 angstroms apart and bridged monodentately by Asp164. The iron is further coordinated by Tyr167, His325, and Asp135, and the zinc by His286, His323, and Asn201. The active-site structure is consistent with previous proposals regarding the mechanism of phosphate ester hydrolysis involving nucleophilic attack on the phosphate group by an Fe(III)-coordinated hydroxide ion.

409 citations

Journal ArticleDOI
TL;DR: An updated review of the current understanding of metallohydrolase-catalyzed reactions is presented, focusing on four systems, purple acid phosphatases, Ser/Thr protein phosph atases, PPs, 3′-5′ exonucleases, and 5′-nucleotidases, which have contributed to major advancement of the understanding of the catalytic mechanisms that operate in such enzymes.
Abstract: With the aim of critically assessing the current models for metal ion assisted hydrolytic reaction mechanisms, an updated review of the current understanding of metallohydrolase-catalyzed reactions is presented. Focus is on four systems, purple acid phosphatases (PAPs), Ser/Thr protein phosphatases (PPs), 3′-5′ exonucleases, and 5′-nucleotidases (5′-NTs), which have contributed to major advancement of the understanding of the catalytic mechanisms that operate in such enzymes.

390 citations

Journal ArticleDOI
TL;DR: All three structures reported herein support a mechanism of phosphate ester hydrolysis involving interaction of the substrate with Zn(II) followed by a nucleophilic attack on the phosphorus by an Fe(III)-coordinated hydroxide ion.

353 citations

Journal ArticleDOI
TL;DR: It is proposed that AtACP5 could be involved in phosphate mobilisation and in the metabolism of reactive oxygen species in stressed or senescent parts of the plant.
Abstract: Low phosphorous availability, a common condition of many soils, is known to stimulate phosphatase activity in plants; however, the molecular details of this response remain mostly unknown. We purified and sequenced the N-terminal region of a phosphate starvation induced acid phosphatase (AtACP5) from Arabidopsis thaliana, and cloned its cDNA and the corresponding genomic DNA. The nucleotide sequence of the cDNA predicted that AtACP5 is synthesised as a 338 amino acid-long precursor with a signal peptide. AtACP5 was found to be related to known purple acid phosphatases, especially to mammal type 5 acid phosphatases. Other similarities with purple acid phosphatases, which contain a dinuclear metal centre, include the conservation of all residues involved in metal ligand binding and resistance to tartrate inhibition. In addition, AtACP5, like other type 5 acid phosphatases, displayed peroxidation activity. Northern hybridisation experiments, as well as in situ glucuronidase (GUS) activity assays on transgenic plants harbouring AtACP5:GUS translational fusions, showed that AtACP5 is not only responsive to phosphate starvation but also to ABA and salt stress. It is also expressed in senescent leaves and during oxidative stress induced by H2O2, but not by paraquat or salicylic acid. Given its bifunctionality, as it displays both phosphatase and peroxidation activity, we propose that AtACP5 could be involved in phosphate mobilisation and in the metabolism of reactive oxygen species in stressed or senescent parts of the plant.

299 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20221
20211
20205
20197
20184
20173