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/Author (Popovic, Dragan and Djordjevic, Ivana)
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/Title ({Catalytic center of cytochrome c oxidase: Effects of protein environment on pKa values of cub histidine ligands})
/bibtex#2FPAGES (1429--1444)
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/Subject (Molecular mechanism by which the electron transfer \(ET\) is coupled to proton pumping in cytochrome oxidase is one of main unsolved problems in biochemistry. Particularly, the nature and position of the proton-loading site is under dispute. The CuB complex has three ligated histidines, whereas only His290 and His291 are ionizable sites with the equal pKas in aqueous solution, but apparently quite different ones within the enzyme. Earlier, it was proposed a model of proton pumping with the central role of His290. Recent calculations indicate that His291 ligand of CuB center might play the role of the pumping element, since its protonation state depends on the oxidation state of the binuclear complex \(BNC\). The present electrostatic study is applied to assess the role of the protein environment on acidity of the two histidines. Their pKa values and effects of different energy terms are evaluated to discover the nature of their diverse behavior in the enzyme. Here, a new set of pKas for the non-standard model compounds within the BNC is applied. The enhanced results are compared with results of previous studies in the light of the plausible proton pumping mechanism. The obtained microscopic and apparent pKa values in the oxidized state of BNC are virtually the same, indicating that deprotonated form of His291 accounts for the large pKa increase of His290, since the both titratable sites on CuB center cannot simultaneously be in the charged state. The present results support the underlined His291 pumping model. [Projects of the Serbian Ministry of Education, Science and Technological Development, Grant no. 451-03-68/2020-14/200026 and Grant no. OI 172035]nema)
/bibtex#2FPUBLISHER (Serbian Chemical Society)
/bibtex#2FISSN (0352-5139)
/bibtex#2FURL (https://www.shd-pub.org.rs/index.php/JSCS/article/view/9721)
/Keywords (Bioenergetics,binuclear complex,bovine,histidine ligands,linear Poisson-Boltzmann equation,pK a calculations,reaction and protein field)
/bibtex#2FYEAR (2020)
/bibtex#2FKEY_FIELD (Popovic2020)
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/bibtex#2FDOI (10.2298/jsc200720047p)
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Molecular mechanism by which the electron transfer (ET) is coupled to proton pumping in cytochrome oxidase is one of main unsolved problems in biochemistry. Particularly, the nature and position of the proton-loading site is under dispute. The CuB complex has three ligated histidines, whereas only His290 and His291 are ionizable sites with the equal pKas in aqueous solution, but apparently quite different ones within the enzyme. Earlier, it was proposed a model of proton pumping with the central role of His290. Recent calculations indicate that His291 ligand of CuB center might play the role of the pumping element, since its protonation state depends on the oxidation state of the binuclear complex (BNC). The present electrostatic study is applied to assess the role of the protein environment on acidity of the two histidines. Their pKa values and effects of different energy terms are evaluated to discover the nature of their diverse behavior in the enzyme. Here, a new set of pKas for the non-standard model compounds within the BNC is applied. The enhanced results are compared with results of previous studies in the light of the plausible proton pumping mechanism. The obtained microscopic and apparent pKa values in the oxidized state of BNC are virtually the same, indicating that deprotonated form of His291 accounts for the large pKa increase of His290, since the both titratable sites on CuB center cannot simultaneously be in the charged state. The present results support the underlined His291 pumping model. [Projects of the Serbian Ministry of Education, Science and Technological Development, Grant no. 451-03-68/2020-14/200026 and Grant no. OI 172035]nema
Dragan Popovic
Ivana Djordjevic
bibtex/bibtexkey/Popovic2020
bibtex/file/:C\:/Users/Dekanski/AppData/Local/Mendeley Ltd./Mendeley Desktop/Downloaded/Popovic, Djordjevic - 2020 - Catalytic center of cytochrome c oxidase Effects of protein environment on pKa values of cub histidine liga.pdf:pdf;:D\:/Dokumenti/Dropbox/02_SHD-WEB/JSCS/Vol85/No11_2020_www/04_9721_5385.pdf:PDF
bibtex/issn/0352-5139
bibtex/journal/Journal of the Serbian Chemical Society
bibtex/month/nov
bibtex/number/11
bibtex/pages/1429--1444
bibtex/url/https://www.shd-pub.org.rs/index.php/JSCS/article/view/9721
bibtex/volume/85
10.2298/jsc200720047p
Bioenergetics
binuclear complex
bovine
histidine ligands
linear Poisson-Boltzmann equation
pK a calculations
reaction and protein field
Serbian Chemical Society
{Catalytic center of cytochrome c oxidase: Effects of protein environment on pKa values of cub histidine ligands}
2020-11
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