Diferenzas entre revisións de «Citocromo f»

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O '''citocromo ''f''''' (cyt f) é a subunidade máis grande do [[complexo do citocromo b6f|complexo do citocromo ''b''<sub>6</sub>''f'']] (plastoquinol&mdash;plastocianina redutase; [[Númeronúmero EC]] 1.10.99.1). Na súa estrutura e funcións, o complexo do citocromo b6f presenta unha grande analoxía co [[complexo do citocromo bc1]] da [[mitocondria]] e das [[bacterias fotosintéticas púrpuras]]. O citocromo f xoga un papel similar ao do citocromo c1, a pesar da súa [[estrutura secundaria das proteínas|estrutura secundaria]] diferente.<ref name="pmid7631417">{{cite journal | author = Prince RC, George GN | title = Cytochrome f revealed | journal = Trends Biochem. Sci. | volume = 20 | issue = 6 | pages = 217–8 |date=June 1995 | pmid = 7631417 | doi = | url = }}</ref>
 
The 3D structure of ''Brassica rapa'' ([[Turnip]]) cyt f has been determined.<ref name="pmid8762139">{{cite journal | author = Martinez SE, Huang D, Ponomarev M, Cramer WA, Smith JL | title = The heme redox center of chloroplast cytochrome f is linked to a buried five-water chain | journal = Protein Sci. | volume = 5 | issue = 6 | pages = 1081–92 |date=June 1996 | pmid = 8762139 | pmc = 2143431 | doi = 10.1002/pro.5560050610 | url = }}</ref> The lumen-side segment of cyt f includes two [[secondary structure|structural]] domains: a small one above a larger one that, in turn, is on top of the attachment to the membrane domain. The large domain consists of an anti-parallel beta-sandwich and a short haem-binding peptide, which form a three-layer [[protein structure|structure]]. The small domain is inserted between beta-strands F and G of the large domain and is an all-beta domain. The haem nestles between two short [[Alpha helix|helices]] at the N terminus of cyt f. Within the second [[helix]] is the [[sequence motif]] for the c-type cytochromes, CxxCH (residues 21-25), which is [[covalently]] attached to the haem through thioether [[Chemical bond|bond]]s to Cys-21 and Cys-24. His-25 is the fifth haem [[iron]] [[ligand (biochemistry)|ligand]]. The sixth haem iron [[Ligand (biochemistry)|ligand]] is the alpha-amino group of Tyr-1 in the first helix.<ref name="pmid8762139">{{cite journal | author = Martinez SE, Huang D, Ponomarev M, Cramer WA, Smith JL | title = The heme redox center of chloroplast cytochrome f is linked to a buried five-water chain | journal = Protein Sci. | volume = 5 | issue = 6 | pages = 1081–92 |date=June 1996 | pmid = 8762139 | pmc = 2143431 | doi = 10.1002/pro.5560050610 | url = }}</ref> Cyt f has an internal network of [[water]] molecules that may function as a proton wire.<ref name="pmid8762139">{{cite journal | author = Martinez SE, Huang D, Ponomarev M, Cramer WA, Smith JL | title = The heme redox center of chloroplast cytochrome f is linked to a buried five-water chain | journal = Protein Sci. | volume = 5 | issue = 6 | pages = 1081–92 |date=June 1996 | pmid = 8762139 | pmc = 2143431 | doi = 10.1002/pro.5560050610 | url = }}</ref> The water [[polymer|chain]] appears to be a [[conserved sequence|conserved]] feature of cyt f.
 
TheDeterminouse 3Da structureestrutura oftridimensional do citocromo f de ''Brassica rapa'' ([[Turnipnabo]]) cyt f has been determined.<ref name="pmid8762139">{{cite journal | author = Martinez SE, Huang D, Ponomarev M, Cramer WA, Smith JL | title = The heme redox center of chloroplast cytochrome f is linked to a buried five-water chain | journal = Protein Sci. | volume = 5 | issue = 6 | pages = 1081–92 |date=June 1996 | pmid = 8762139 | pmc = 2143431 | doi = 10.1002/pro.5560050610 | url = }}</ref> The lumen-side segment of cyt f includes two [[secondary structure|structural]] domains: a small one above a larger one that, in turn, is on top of the attachment to the membrane domain. The large domain consists of an anti-parallel beta-sandwich and a short haem-binding peptide, which form a three-layer [[protein structure|structure]]. The small domain is inserted between beta-strands F and G of the large domain and is an all-beta domain. The haem nestles between two short [[Alpha helix|helices]] at the N terminus of cyt f. Within the second [[helix]] is the [[sequence motif]] for the c-type cytochromes, CxxCH (residues 21-25), which is [[covalently]] attached to the haem through thioether [[Chemical bond|bond]]s to Cys-21 and Cys-24. His-25 is the fifth haem [[iron]] [[ligand (biochemistry)|ligand]]. The sixth haem iron [[Ligand (biochemistry)|ligand]] is the alpha-amino group of Tyr-1 in the first helix.<ref name="pmid8762139">{{cite journal | author = Martinez SE, Huang D, Ponomarev M, Cramer WA, Smith JL | title = The heme redox center of chloroplast cytochrome f is linked to a buried five-water chain | journal = Protein Sci. | volume = 5 | issue = 6 | pages = 1081–92 |date=June 1996 | pmid = 8762139 | pmc = 2143431 | doi = 10.1002/pro.5560050610 | url = }}</ref> Cyt f has an internal network of [[water]] molecules that may function as a proton wire.<ref name="pmid8762139">{{cite journal | author = Martinez SE, Huang D, Ponomarev M, Cramer WA, Smith JL | title = The heme redox center of chloroplast cytochrome f is linked to a buried five-water chain | journal = Protein Sci. | volume = 5 | issue = 6 | pages = 1081–92 |date=June 1996 | pmid = 8762139 | pmc = 2143431 | doi = 10.1002/pro.5560050610 | url = }}</ref> The water [[polymer|chain]] appears to be a [[conserved sequence|conserved]] feature of cyt f.
 
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