Abstract:
:Recent models for water oxidation in photosystem II postulate that the tyrosine Y(Z) radical, Y(Z)(*), abstracts both an electron and a proton from the Mn cluster during one or more steps in the catalytic cycle. This coupling of proton- and electron-transfer events is postulated to provide the necessary driving force for oxidizing the Mn cluster in its higher oxidation states. The formation of Y(Z)(*) requires the deprotonation of Y(Z) by His190 of the D1 polypeptide. For Y(Z)(*) to abstract both an electron and a proton from the Mn cluster, the proton abstracted from Y(Z) must be transferred rapidly from D1-His190 to the lumenal surface via one or more proton-transfer pathways. The proton acceptor for D1-His190 has been proposed to be either Glu189 of the D1 polypeptide or a group positioned by this residue. To further define the role of D1-Glu189, 17 D1-Glu189 mutations were constructed in the cyanobacterium Synechocystis sp. PCC 6803. Several of these mutants are of particular interest because they appear to assemble Mn clusters in 70-80% of reaction centers in vivo, but evolve no O(2). The EPR and electron-transfer properties of PSII particles isolated from the D1-E189Q, D1-E189L, D1-E189D, D1-E189N, D1-E189H, D1-E189G, and D1-E189S mutants were examined. Intact PSII particles isolated from mutants that evolved no O(2) also exhibited no S(1) or S(2) state multiline EPR signals and were unable to advance beyond an altered Y(Z)(*)S(2) state, as shown by the accumulation of narrow "split" EPR signals under multiple turnover conditions. In the D1-E189G and D1-E189S mutants, the quantum yield for oxidizing the S(1) state Mn cluster was very low, corresponding to a > or =1400-fold slowing of the rate of Mn oxidation by Y(Z)(*). In Mn-depleted D1-Glu189 mutant PSII particles, charge recombination between Q(A)(*)(-) and Y(Z)(*) in the mutants was accelerated, showing that the mutations alter the redox properties of Y(Z) in addition to those of the Mn cluster. These results are consistent with D1-Glu189 participating in a network of hydrogen bonds that modulates the properties of both Y(Z) and the Mn cluster and are consistent with proposals that D1-Glu189 positions a group that accepts a proton from D1-His190.
journal_name
Biochemistryjournal_title
Biochemistryauthors
Debus RJ,Campbell KA,Pham DP,Hays AM,Britt RDdoi
10.1021/bi992749wsubject
Has Abstractpub_date
2000-05-30 00:00:00pages
6275-87issue
21eissn
0006-2960issn
1520-4995pii
bi992749wjournal_volume
39pub_type
杂志文章相关文献
BIOCHEMISTRY文献大全abstract::Endonuclease V from bacteriophage T4 is a well characterized enzyme that initiates the repair of ultraviolet light induced pyrimidine dimers. Scission of the phosphodiester backbone between the pyrimidines within a dimer, or 3' to an abasic (AP) site, occurs by a beta-elimination mechanism. In addition, high concentra...
journal_title:Biochemistry
pub_type: 杂志文章
doi:10.1021/bi00027a031
更新日期:1995-07-11 00:00:00
abstract::OleD is shown to play a key reductive role in the generation of alkenes (olefins) from acyl thioesters in Stenotrophomonas maltophilia. The gene coding for OleD clusters with three other genes, oleABC, and all appear to be transcribed in the same direction as an operon in various olefin producing bacteria. In this stu...
journal_title:Biochemistry
pub_type: 杂志文章
doi:10.1021/bi201096w
更新日期:2011-11-08 00:00:00
abstract::R67 dihydrofolate reductase (DHFR) is a novel homotetrameric protein that possesses 222 symmetry and a single, voluminous active site pore. This symmetry poses numerous limitations on catalysis; for example, two dihydrofolate (DHF) molecules or two NADPH molecules, or one substrate plus one cofactor can bind. Only the...
journal_title:Biochemistry
pub_type: 杂志文章
doi:10.1021/bi052504l
更新日期:2006-05-30 00:00:00
abstract::ATP, its nonhydrolyzable analogue, AMP-PNP, and albumin were found to promote the dissociation of rhodopsin kinase from rod outer segments (ROS) containing photoactivated-rhodopsin (Rho*). These features were embodied in a protocol for the recovery of rhodopsin kinase from incubations containing ROS which had been sub...
journal_title:Biochemistry
pub_type: 杂志文章
doi:10.1021/bi952480q
更新日期:1996-05-14 00:00:00
abstract::Pancreatic and duodenal homeobox 1 (Pdx1) is a homeodomain transcription factor belonging to the ParaHox family. Pdx1 plays an essential role in pancreatic endocrine and exocrine cell development and maintenance of adult islet beta-cell function. Mutations in the human pdx1 gene are linked to an early onset form of no...
journal_title:Biochemistry
pub_type: 杂志文章
doi:10.1021/bi060969l
更新日期:2007-03-20 00:00:00
abstract::Periodate-oxidized ATP (o-ATP) was prepared as an affinity label of nucleotide binding sites on the chloroform-released ox heart mitochondrial ATPase. In the presence of MgSO4, o-ATP is a substrate for the ATPase. It can act as a reversible, competitive inhibitor of ATPase activity and can also induce an irreversible ...
journal_title:Biochemistry
pub_type: 杂志文章
doi:10.1021/bi00260a025
更新日期:1982-08-17 00:00:00
abstract::The association-dissociation kinetics of ribosomes from Escherichia coli have been studied under various conditions in a light-scattering stopped-flow apparatus. The dissociation reaction at 2 mg/ml at 25 degrees C, induced by lowering the MgCl2 concentration from 18 to 3 mM, can best be described by three independent...
journal_title:Biochemistry
pub_type: 杂志文章
doi:10.1021/bi00671a010
更新日期:1976-12-28 00:00:00
abstract::The hallmark of serpins is the ability to undergo the so-called "stressed-to-relaxed" switch during which the surface-exposed reactive center loop (RCL) becomes incorporated as strand 4 in central beta-sheet A. RCL insertion drives not only the inhibitory reaction of serpins with their target serine proteases but also...
journal_title:Biochemistry
pub_type: 杂志文章
doi:10.1021/bi100066j
更新日期:2010-05-18 00:00:00
abstract::12-Iodo-cis-9-octadecenoic acid (12-IODE) is a time-dependent, irreversible inactivator of soybean lipoxygenase 1. The rate of inactivation is independent of 12-IODE concentration above 20 microM and is half-maximal at about 4 microM. Inactivation by 12-IODE requires lipid hydroperoxide, which must be present even aft...
journal_title:Biochemistry
pub_type: 杂志文章
doi:10.1021/bi00424a019
更新日期:1988-11-29 00:00:00
abstract::Hydrolysis of monodisperse short chain phosphatidylcholines, far below their critical micelle concentration, by phospholipase A2 (PLA2) and other interfacial enzymes is characterized. Results show that virtually all the observed hydrolysis by pancreatic and human inflammatory PLA2 occurs on surfaces of the reaction ve...
journal_title:Biochemistry
pub_type: 杂志文章
doi:10.1021/bi990194z
更新日期:1999-08-10 00:00:00
abstract::Cooperative binding of the bacteriophage lambda cI repressor dimer to specific sites of the phage operators OR and OL controls the developmental state of the phage. Cooperativity has long been thought to be mediated by self-assembly of repressor dimers to form tetramers which can bind simultaneously to adjacent operat...
journal_title:Biochemistry
pub_type: 杂志文章
doi:10.1021/bi971368k
更新日期:1997-10-21 00:00:00
abstract::Under conditions where muscle actin only partially polymerizes, or where it does not polymerize at all, a significant enhancement of polymerization was observed if equimolar phalloidin was also present. The increased extent of polymerization in the the presence of phalloidin can be explained by the reduced critical ac...
journal_title:Biochemistry
pub_type: 杂志文章
doi:10.1021/bi00507a006
更新日期:1981-02-17 00:00:00
abstract::For the elucidation of the mechanism of steroid hormone receptor activation, the hydrodynamic properties of the unactivated and activated forms of the nonproteolyzed glucocorticoid receptor from the mouse AtT-20 pituitary tumor cell line were determined. The unactivated, molybdate-stabilized receptor has the following...
journal_title:Biochemistry
pub_type: 杂志文章
doi:10.1021/bi00277a038
更新日期:1983-04-12 00:00:00
abstract::Interleukin-8 (IL-8), a member of the chemokine superfamily, exists as both monomers and dimers, and mediates its function by binding to neutrophil CXCR1 and CXCR2 receptors that belong to the G protein-coupled receptor class. It is now well established that the monomer functions as a high-affinity ligand, but the bin...
journal_title:Biochemistry
pub_type: 杂志文章
doi:10.1021/bi0605944
更新日期:2006-06-27 00:00:00
abstract::It is generally accepted that electron transfer in bacterial photosynthesis is driven by the first singlet excited state of a special pair of bacteriochlorophylls (P*). We have examined the first steps of electron transfer in a mutant of the Rhodobacter sphaeroides reaction center in which charge separation from P* is...
journal_title:Biochemistry
pub_type: 杂志文章
doi:10.1021/bi9703756
更新日期:1997-06-10 00:00:00
abstract::The manganese transport regulator (MntR) of Bacillus subtilis is activated by Mn(2+) to repress transcription of genes encoding transporters involved in the uptake of manganese. MntR is also strongly activated by cadmium, both in vivo and in vitro, but it is poorly activated by other metal cations, including calcium a...
journal_title:Biochemistry
pub_type: 杂志文章
doi:10.1021/bi0524215
更新日期:2006-03-21 00:00:00
abstract::The dynamics of the enthalpy and volume changes found in the photodissociation of CO from sperm whale carboxymyoglobin and two site-directed mutants in which arginine-45 is replaced by glycine and asparagine are examined by photoacoustic calorimetry. An intermediate is observed whose lifetime at 20 degrees C is 700 ns...
journal_title:Biochemistry
pub_type: 杂志文章
doi:10.1021/bi00480a026
更新日期:1990-07-17 00:00:00
abstract::Aromatic amino acid aminotransferase (ArAT) from Escherichia coli was overexpressed in E. coli cells, purified, and characterized. The enzyme was similar to aspartate aminotransferase (AspAT) of E. coli in many aspects, such as gross protein structure and spectroscopic properties. The reactions of pyridoxal 5'-phospha...
journal_title:Biochemistry
pub_type: 杂志文章
doi:10.1021/bi00096a036
更新日期:1993-11-16 00:00:00
abstract::The relationship between cholesterol and ubiquinone synthesis in rat intestinal epithelial cell cultures was examined by using 3 beta-[2-(diethylamino)ethoxy]androst-5-en-17-one hydrochloride (U18666A). Addition of U18666A to cells caused a greater than 90% inhibition of incorporation of [3H]acetate into cholesterol a...
journal_title:Biochemistry
pub_type: 杂志文章
doi:10.1021/bi00294a001
更新日期:1983-12-06 00:00:00
abstract::The effect of DNA supercoiling on a sterically very demanding threading intercalation process is investigated here. We find that the threading rate of a dimeric ruthenium complex into a negatively supercoiled plasmid at low binding density is 2 orders of magnitude higher than into the cleaved linear form. Further satu...
journal_title:Biochemistry
pub_type: 杂志文章
doi:10.1021/bi802336p
更新日期:2009-02-24 00:00:00
abstract::Superoxide reductase (SOR) is an Fe protein that catalyzes the reduction of superoxide to give H(2)O(2). Recently, the mutation of the Glu47 residue into alanine (E47A) in the active site of SOR from Desulfoarculus baarsii has allowed the stabilization of an iron-peroxo species when quickly reacted with H(2)O(2) [Math...
journal_title:Biochemistry
pub_type: 杂志文章
doi:10.1021/bi0498151
更新日期:2004-07-13 00:00:00
abstract::Many current models of the Q cycle for the cytochrome (cyt) b6f and the cyt bc1 complexes incorporate 'Rieske' iron-sulfur protein (ISP) domain movements to gate electron transfer and to ensure high yields of proton shuttling. It was previously proposed that copper ions, which bind at a site distant from the quinol ox...
journal_title:Biochemistry
pub_type: 杂志文章
doi:10.1021/bi015996k
更新日期:2002-03-26 00:00:00
abstract::Ligand-dependent site-site (or subunit-subunit) interactions provide the basis for explaining cooperativity in chemical reactions. Even in the simplest possible nonaggregating system, interpretation of the interactions in terms of structural details requires an explicit assumption (or model) for the binding of the lig...
journal_title:Biochemistry
pub_type: 杂志文章,评审
doi:10.1021/bi00106a004
更新日期:1991-10-22 00:00:00
abstract::Cathepsin L, a lysosomal cysteine protease, is overexpressed and secreted by malignantly transformed cells. However, the reason for secretion of this man 6-phosphate-containing lysosomal protease into the extracellular medium is not clear. We wished to determine whether there is a region within the primary sequence of...
journal_title:Biochemistry
pub_type: 杂志文章
doi:10.1021/bi972251z
更新日期:1998-06-09 00:00:00
abstract::Human secretory group IIa phospholipase A2 (hIIa-PLA2) contains a large number of prominent cationic patches on its molecular surface and has exceptionally high affinity for anionic surfaces, including anionic membranes. To identify the cationic amino acid residues that support binding of hIIa-PLA2 to anionic membrane...
journal_title:Biochemistry
pub_type: 杂志文章
doi:10.1021/bi971200z
更新日期:1997-11-25 00:00:00
abstract::The structure of the anti-inflammatory drug diclofenac bound in the active site of rabbit microsomal cytochrome P450 2C5/3LVdH was determined by X-ray crystallography to 2.1 A resolution. P450 2C5/3LVdH and the related enzyme 2C5dH catalyze the 4'-hydroxylation of diclofenac with apparent K(m) values of 80 and 57 micr...
journal_title:Biochemistry
pub_type: 杂志文章
doi:10.1021/bi034556l
更新日期:2003-08-12 00:00:00
abstract::We report the use of electrospray ionization (ESI) mass spectrometry (MS) in conjunction with online rapid mixing to monitor the kinetics of acid-induced ferrihemoglobin denaturation. Under equilibrium conditions, the hemoglobin mass spectrum is dominated by the intact heterotetramer. Dimeric and monomeric species are...
journal_title:Biochemistry
pub_type: 杂志文章
doi:10.1021/bi048501a
更新日期:2004-11-23 00:00:00
abstract::FixL is a heme-based oxygen-sensing histidine kinase that induces the expression of nitrogen fixation genes under hypoxic conditions. Oxygen dissociation from heme iron in the sensor domain of FixL initiates protein conformational changes that are transmitted to the histidine kinase domain, activating autophosphorylat...
journal_title:Biochemistry
pub_type: 杂志文章
doi:10.1021/acs.biochem.6b00405
更新日期:2016-07-26 00:00:00
abstract::In this paper, we examined the posttranslational modifications (PTMs) of high-mobility group A1 (HMGA1) proteins in PC-3 human prostate cancer cells that are either treated or not treated with a histone deacetylase inhibitor, sodium butyrate. We found that, from a reversed-phase C4 column, the HMGA1a protein eluted in...
journal_title:Biochemistry
pub_type: 杂志文章
doi:10.1021/bi060504v
更新日期:2006-06-13 00:00:00
abstract::The coat protein of bacteriophage Pf3 forms discrete and stable ion channels of uniform size in planar bilayers of asolectin. Its primary sequence suggests a channel formed by a bundle of transmembrane helices. Since the apparent transmembrane region only consists of strongly hydrophobic residues, it represents a new ...
journal_title:Biochemistry
pub_type: 杂志文章
doi:10.1021/bi00167a037
更新日期:1994-01-11 00:00:00