The radiolysis of protein A

Moore, J.S.; Sakhri, Mohamed; Butler, J. A. V.

doi:10.1016/s0969-806x(99)00518-6

Cited by 5 publications

(3 citation statements)

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“…The radiolysis of water with ionizing radiation produces electrons, free radicals (H· radicals and ·OH radicals) and hydrogen peroxide H 2 O 2 via free radical mechanisms (50). When proteins are irradiated in aqueous solution, the reactive oxygen species, namely, ·OH free radicals, could attack specific amino acids or the groups of amino acids, such as histidine, tyrosine, tryptophan, cysteine, and methionine, in the active site, leading to protein inactivation (19,41,48,51). The residues could interact with water-derived radicals because of the readily oxidizable functional groups, including indole, phenol, aromatic, and thiol groups.…”

Section: Discussionmentioning

confidence: 99%

Crystal Structures of Complexes of the Branched-Chain Aminotransferase from Deinococcus radiodurans with α-Ketoisocaproate and l- Glutamate Suggest the Radiation Resistance of This Enzyme for Catalysis

et al. 2012

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dBranched-chain aminotransferases (BCAT), which utilize pyridoxal 5=-phosphate (PLP) as a cofactor, reversibly catalyze the transfer of the ␣-amino groups of three of the most hydrophobic branched-chain amino acids (BCAA), leucine, isoleucine, and valine, to ␣-ketoglutarate to form the respective branched-chain ␣-keto acids and glutamate. The BCAT from Deinococcus radiodurans (DrBCAT), an extremophile, was cloned and expressed in Escherichia coli for structure and functional studies. The crystal structures of the native DrBCAT with PLP and its complexes with L-glutamate and ␣-ketoisocaproate (KIC), respectively, have been determined. The DrBCAT monomer, comprising 358 amino acids, contains large and small domains connected with an interdomain loop. The cofactor PLP is located at the bottom of the active site pocket between two domains and near the dimer interface. The substrate (L-glutamate or KIC) is bound with key residues through interactions of the hydrogen bond and the salt bridge near PLP inside the active site pocket. Mutations of some interaction residues, such as Tyr71, Arg145, and Lys202, result in loss of the specific activity of the enzymes. In the interdomain loop, a dynamic loop (Gly173 to Gly179) clearly exhibits open and close conformations in structures of DrBCAT without and with substrates, respectively. DrBCAT shows the highest specific activity both in nature and under ionizing radiation, but with lower thermal stability above 60°C, than either BCAT from Escherichia coli (eBCAT) or from Thermus thermophilus (HB8BCAT). The dimeric molecular packing and the distribution of cysteine residues at the active site and the molecular surface might explain the resistance to radiation but small thermal stability of DrBCAT.

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Section: Discussionmentioning

confidence: 99%

Crystal Structures of Complexes of the Branched-Chain Aminotransferase from Deinococcus radiodurans with α-Ketoisocaproate and l- Glutamate Suggest the Radiation Resistance of This Enzyme for Catalysis

et al. 2012

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“…It is believed that superoxide anion radical shows low reactivity and in the oxidative stress it is regarded mainly as an initiator of more reactive species such as d OH and ONOO À (Gebicki, 2006). Several papers devoted to the direct influence of O 2 d À on proteins prove that this radical can play a significant part in the destruction and loss of enzyme activity (Moore et al, 2000;Hasan et al, 1994;Badiello et al, 1974;Saha et al, 1995).…”

Section: Discussionmentioning

confidence: 99%

“…If these residues are situated inside or near the protein's active site, the superoxide radical can also cause significant inactivation of the enzyme. Moore et al (2000) in the work on the radiolysis of protein A estimated that superoxide is as efficient as the hydroxyl radical in this protein inactivation. Similar observations regarding alcohol dehydrogenase were made by Badiello et al (1974).…”

Section: Introductionmentioning

confidence: 99%

Efficiency of superoxide anions in the inactivation of selected dehydrogenases

Rodacka

Serafin

Puchała

2010

Radiation Physics and Chemistry

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Reactive Oxygen Species

2012

Oxidation of Amino Acids, Peptides, and Proteins

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Reactive oxygen species (ROS) are generated in mammalian cells via both enzymatic and non-enzymatic mechanisms. Although certain ROS production pathways are required for the performance of specific physiological functions, excessive ROS generation is harmful, and has been implicated in the pathogenesis of a number of diseases. Among the ROS-producing enzymes, NADPH oxidase is widely distributed among mammalian cells, and is a crucial source of ROS for physiological and pathological processes. Reactive oxygen species are also generated by arachidonic acid (AA) metabolites, which are released from membrane phospholipids via the activity of cytosolic phospholipase A2 (cPLA2). In this study, we describe recent studies concerning the generation of ROS by AA metabolites. In particular, we have focused on the manner in which AA metabolism via lipoxygenase (LOX) and LOX metabolites contributes to ROS generation. By elucidating the signaling mechanisms that link LOX and LOX metabolites to ROS, we hope to shed light on the variety of physiological and pathological mechanisms associated with LOX metabolism. [BMB reports 2008; 41(8): 555-559]Reactive oxygen species (ROS) are highly reactive O2 metabolites, such as superoxide radicals (O2 •−

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The radiolysis of protein A

Cited by 5 publications

References 33 publications

Crystal Structures of Complexes of the Branched-Chain Aminotransferase from Deinococcus radiodurans with α-Ketoisocaproate and l- Glutamate Suggest the Radiation Resistance of This Enzyme for Catalysis

Crystal Structures of Complexes of the Branched-Chain Aminotransferase from Deinococcus radiodurans with α-Ketoisocaproate and l- Glutamate Suggest the Radiation Resistance of This Enzyme for Catalysis

Efficiency of superoxide anions in the inactivation of selected dehydrogenases

Reactive Oxygen Species

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