Stopped-flow and steady-state study of the diphenolase activity of mushroom tyrosinase.


:The reaction of mushroom (Agaricus bisporus) tyrosinase with dioxygen in the presence of several o-diphenolic substrates has been studied by steady-state and transient-phase kinetics in order to elucidate the rate-limiting step and to provide new insights into the mechanism of oxidation of these substrates. A kinetic analysis has allowed for the first time the determination of individual rate constants for several of the partial reactions that comprise the catalytic cycle. Mushroom tyrosinase rapidly reacts with dioxygen with a second-order rate constant k(+8) = 2.3 x 10(7) M(-)(1) s(-)(1), which is similar to that reported for hemocyanins [(1.3 x 10(6))-(5.7 x 10(7)) M(-)(1) s(-)(1)]. Deoxytyrosinase binds dioxygen reversibly at the binuclear Cu(I) site with a dissociation constant K(D)(O)()2 = 46.6 microM, which is similar to the value (K(D)(O)()2 = 90 microM) reported for the binding of dioxygen to Octopus vulgaris deoxyhemocyanin [Salvato et al. (1998) Biochemistry 37, 14065-14077]. Transient and steady-state kinetics showed that o-diphenols such as 4-tert-butylcatechol react significantly faster with mettyrosinase (k(+2) = 9.02 x 10(6) M(-)(1) s(-)(1)) than with oxytyrosinase (k(+6) = 5.4 x 10(5) M(-)(1) s(-)(1)). This difference is interpreted in terms of differential steric and polar effects that modulate the access of o-diphenols to the active site for these two forms of the enzyme. The values of k(cat) for several o-diphenols are also consistent with steric and polar factors controlling the mobility, orientation, and thence the reactivity of substrates at the active site of tyrosinase.






Rodríguez-López JN,Fenoll LG,García-Ruiz PA,Varón R,Tudela J,Thorneley RN,García-Cánovas F




Has Abstract


2000-08-29 00:00:00














  • Glycosylated polyproline II rods with kinks as a structural motif in plant hydroxyproline-rich glycoproteins.

    abstract::Hydroxyproline-rich glycoproteins (HRGPs) are the major proteinaceous components of higher plant walls and the predominant components of the cell wall of the green alga Chlamydomonas reinhardtii. The GP1 protein, an HRGP of the C. reinhardtii wall, is shown to adopt a polyproline II helical configuration and to carry ...


    pub_type: 杂志文章


    authors: Ferris PJ,Woessner JP,Waffenschmidt S,Kilz S,Drees J,Goodenough UW

    更新日期:2001-03-06 00:00:00

  • Carboxylate ions are strong allosteric ligands for the HisB10 sites of the R-state insulin hexamer.

    abstract::The insulin hexamer is an allosteric protein which displays positive and negative cooperativity and half-site reactivity that is modulated by strong homotropic and heterotropic ligand binding interactions at two different loci. These loci consist of phenolic pockets situated on the dimer-dimer interfaces of T-R and R-...


    pub_type: 杂志文章


    authors: Huang ST,Choi WE,Bloom C,Leuenberger M,Dunn MF

    更新日期:1997-08-12 00:00:00

  • Kinetics and mechanism of transitions involving the lamellar, cubic, inverted hexagonal, and fluid isotropic phases of hydrated monoacylglycerides monitored by time-resolved X-ray diffraction.

    abstract::A study of the dynamics and mechanism of the various thermotropic phase transitions undergone by the hydrated monoacylglycerides monoolein and monoelaidin, in the temperature range of 20-120 degrees C and from 0 to 5 M NaCl, has been undertaken. Measurements were made by using time-resolved X-ray diffraction at the Co...


    pub_type: 杂志文章


    authors: Caffrey M

    更新日期:1987-10-06 00:00:00

  • New clevable photoreactive heterobifunctional cross-linking reagents for studying membrane organization.

    abstract::The synthesis is described of four new cleavable, photosensitive, heterobifunctional cross-linking reagents for use in examining membrane organization: 4'-azidoazobenzene-4oxysuccinimide ester (1), N-[4-(p-azidophenylazo)benzoyl]-3-aminopropyl-N'-oxysuccinimide ester (2), N-[4-(p-azidophenylazo)benzoyl]-6-aminohexyl-N...


    pub_type: 杂志文章


    authors: Jaffe CL,Lis H,Sharon N

    更新日期:1980-09-16 00:00:00

  • Involvement of insulin-like growth factor type 1 receptor and protein kinase Cdelta in bis(maltolato)oxovanadium(IV)-induced phosphorylation of protein kinase B in HepG2 cells.

    abstract::Vanadium(IV) oxo-bis(maltolato) (BMOV), an organovanadium compound, is a potent insulinomimetic agent and improves glucose homeostasis in various models of diabetes. We have shown previously that BMOV stimulates the phosphorylation of PKB which may contribute as one of the mechanisms for the insulinomimetic effect of ...


    pub_type: 杂志文章


    authors: Mehdi MZ,Vardatsikos G,Pandey SK,Srivastava AK

    更新日期:2006-09-26 00:00:00

  • Tryptophan 500 and arginine 707 define product and substrate active site binding in soybean lipoxygenase-1.

    abstract::There is much debate whether the fatty acid substrate of lipoxygenase binds "carboxylate-end first" or "methyl-end first" in the active site of soybean lipoxygenase-1 (sLO-1). To address this issue, we investigated the sLO-1 mutants Trp500Leu, Trp500Phe, Lys260Leu, and Arg707Leu with steady-state and stopped-flow kine...


    pub_type: 杂志文章


    authors: Ruddat VC,Mogul R,Chorny I,Chen C,Perrin N,Whitman S,Kenyon V,Jacobson MP,Bernasconi CF,Holman TR

    更新日期:2004-10-19 00:00:00

  • Atomic resolution (0.94 A) structure of Clostridium acidurici ferredoxin. Detailed geometry of [4Fe-4S] clusters in a protein.

    abstract::The crystal structure of the 2[4Fe-4S] ferredoxin from Clostridium acidurici has been solved using X-ray diffraction data extending to atomic resolution, 0.94 A, recorded at 100 K. The model was refined with anisotropic representation of atomic displacement parameters for all non-hydrogen atoms and with hydrogens ridi...


    pub_type: 杂志文章


    authors: Dauter Z,Wilson KS,Sieker LC,Meyer J,Moulis JM

    更新日期:1997-12-23 00:00:00

  • Detailed structural characterization of unbound protein phosphatase 1 inhibitors.

    abstract::Protein phosphatase 1 (PP1) is an essential and ubiquitous serine/threonine protein phosphatase that is regulated by more than 100 known inhibitor and targeting proteins. It is currently unclear how protein inhibitors distinctly and specifically regulate PP1 to enable rapid responses to cellular alterations. We demons...


    pub_type: 杂志文章


    authors: Dancheck B,Nairn AC,Peti W

    更新日期:2008-11-25 00:00:00

  • Transmembrane topography of the mitochondrial oxoglutarate carrier assessed by peptide-specific antibodies and enzymatic cleavage.

    abstract::The folding of the peptide chain of the bovine heart oxoglutarate carrier in the inner mitochondrial membrane and in the membrane of reconstituted proteoliposomes has been investigated by enzymatic and immunochemical approaches using proteinase K and polyclonal site-directed antibodies, respectively. Two peptides corr...


    pub_type: 杂志文章


    authors: Bisaccia F,Capobianco L,Brandolin G,Palmieri F

    更新日期:1994-03-29 00:00:00

  • Conformational preferences of synthetic peptides derived from the immunodominant site of the circumsporozoite protein of Plasmodium falciparum by 1H NMR.

    abstract::Proton nuclear magnetic resonance and ultraviolet circular dichroism spectroscopy have been used to probe the conformational ensemble of the tandemly repeating tetrapeptide unit of the circumsporozoite coat protein of the malaria parasite Plasmodium falciparum. Peptides based on the Asn-Ala-Asn-Pro and Asn-Pro-Asn-Ala...


    pub_type: 杂志文章


    authors: Dyson HJ,Satterthwait AC,Lerner RA,Wright PE

    更新日期:1990-08-28 00:00:00

  • Conformational insights into the lesion and sequence effects for arylamine-induced translesion DNA synthesis: 19F NMR, surface plasmon resonance, and primer kinetic studies.

    abstract::Adduct-induced DNA damage can affect transcription efficiency and DNA replication and repair. We previously investigated the effects of the 3'-next flanking base (G*CT vs G*CA; G*, FABP, N-(2'-deoxyguanosin-8-yl)-4'-fluoro-4-aminobiphenyl; FAF, N-(2'-deoxyguanosin-8-yl)-7-fluoro-2-aminofluorene) on the conformation of...


    pub_type: 杂志文章


    authors: Jain V,Vaidyanathan VG,Patnaik S,Gopal S,Cho BP

    更新日期:2014-06-24 00:00:00

  • Sequence context- and temperature-dependent nucleotide excision repair of a benzo[a]pyrene diol epoxide-guanine DNA adduct catalyzed by thermophilic UvrABC proteins.

    abstract::The influence of DNA base sequence context on the removal of a bulky benzo[a]pyrene diol epoxide-guanine adduct, (+)-trans-B[a]P-N2-dG (G*), by UvrABC nuclease from the thermophilic organism Bacillus caldotenax was investigated. The lesion was flanked by either T or C in otherwise identical complementary 43-mer duplex...


    pub_type: 杂志文章


    authors: Ruan Q,Liu T,Kolbanovskiy A,Liu Y,Ren J,Skorvaga M,Zou Y,Lader J,Malkani B,Amin S,Van Houten B,Geacintov NE

    更新日期:2007-06-12 00:00:00

  • Generation and characterization of two transgenic mouse lines expressing human ApoE2 in neurons and glial cells.

    abstract::Apolipoprotein E (apoE) isoforms are key determinants of susceptibility to late-onset Alzheimer's disease (AD). The epsilon 4 and epsilon 2 alleles have been associated with increased and decreased risk for AD, respectively. We have generated and characterized transgenic mice in which the human apoE2 gene is expressed...


    pub_type: 杂志文章


    authors: Georgopoulos S,McKee A,Kan HY,Zannis VI

    更新日期:2002-07-30 00:00:00

  • Disentangling the coil: modulation of conformational and dynamic properties by site-directed mutation in the non-native state of hen egg white lysozyme.

    abstract::The conformational analysis of non-native states of proteins remains one of the most difficult problems in structural biology, because such states are represented by a superimposition of several states that are rapidly interconverting. Hence, model building of the conformational ensemble remains challenging, although ...


    pub_type: 杂志文章


    authors: Sziegat F,Silvers R,Hähnke M,Jensen MR,Blackledge M,Wirmer-Bartoschek J,Schwalbe H

    更新日期:2012-04-24 00:00:00

  • An RNA polymerase mutant with reduced accuracy of chain elongation.

    abstract::A new Escherichia coli RNA polymerase mutant was isolated which exhibited reduced accuracy of chain elongation in vivo and in vitro. The novel isolation procedure consisted of simultaneous selection for rifampicin resistance and screening for increased leakiness of an early, strongly polar nonsense mutation of lacZ, o...


    pub_type: 杂志文章


    authors: Blank A,Gallant JA,Burgess RR,Loeb LA

    更新日期:1986-10-07 00:00:00

  • Dynamics of activation of lecithin:cholesterol acyltransferase by apolipoprotein A-I.

    abstract::The product of transesterification of phospholipid acyl chains and unesterified cholesterol (UC) by the enzyme lecithin:cholesterol acyltransferase (LCAT) is cholesteryl ester (CE). Activation of LCAT by apolipoprotein (apo) A-I on nascent (discoidal) high-density lipoproteins (HDL) is essential for formation of matur...


    pub_type: 杂志文章


    authors: Jones MK,Catte A,Li L,Segrest JP

    更新日期:2009-12-01 00:00:00

  • Mutations affecting transition-state stabilization by residues coordinating zinc at the active site of cytidine deaminase.

    abstract::Cytidine deaminase from Escherichia coli contains 1 mol of tightly bound zinc per enzyme subunit (Yang, C., Carlow, D., Wolfenden, R., & Short, S.A. (1992) Biochemistry 31, 4168-4174). When the metal liganding residues Cys-129 and Cys-132 were replaced by Ala, and His-102 was replaced by Ala, Asn, or Gln, deaminase ac...


    pub_type: 杂志文章


    authors: Smith AA,Carlow DC,Wolfenden R,Short SA

    更新日期:1994-05-31 00:00:00

  • Steps toward constructing a cytochrome b6 f complex in the purple bacterium Rhodobacter sphaeroides: an example of the structural plasticity of a membrane cytochrome.

    abstract::We have modified the cytochrome b subunit of the cytochrome bc1 complex from the purple bacterium Rhodobacter sphaeroides to introduce two distinctive features of cytochrome b6 f complexes. In the first one, we have split cyt b into two polypeptides thus mimicking the organization of cyt b6 and subunit IV in the b6 f ...


    pub_type: 杂志文章


    authors: Kuras R,Guergova-Kuras M,Crofts AR

    更新日期:1998-11-17 00:00:00

  • Sulfated glycoproteins, glycolipids, and glycosaminoglycans from synaptic plasma and myelin membranes: isolation and characterization of sulfated glycopeptides.

    abstract::In this report we provide biochemical evidence that a highly purified synaptic plasma membrane fraction derived from rat brain, after intraventricular injection of 35S-labeled sodium sulfate, is enriched in a number of large sulfated glycoproteins compared with a purified myelin fraction studied concurrently. A fracti...


    pub_type: 杂志文章


    authors: Simpson DL,Thorne DR,Loch HH

    更新日期:1976-12-14 00:00:00

  • Temperature-sensitive mutations of bacteriophage T4 lysozyme occur at sites with low mobility and low solvent accessibility in the folded protein.

    abstract::Twenty-five different temperature-sensitive point mutations at 20 sites in the lysozyme gene of bacteriophage T4 have been identified. All of the mutations alter amino acid side chains that have lower than average crystallographic thermal factors and reduced solvent accessibility in the folded protein. This suggests t...


    pub_type: 杂志文章


    authors: Alber T,Sun DP,Nye JA,Muchmore DC,Matthews BW

    更新日期:1987-06-30 00:00:00

  • Stoichiometry and specificity of lipid-protein interaction with myelin proteolipid protein studied by spin-label electron spin resonance.

    abstract::The interaction of spin-labeled lipids with the myelin proteolipid apoprotein in complexes with dimyristoylphosphatidylcholine of varying lipid/protein ratios has been studied with electron spin resonance spectroscopy. A first shell of approximately 10 lipids per 25 000-dalton protein is found to be motionally restric...


    pub_type: 杂志文章


    authors: Brophy PJ,Horváth LI,Marsh D

    更新日期:1984-02-28 00:00:00

  • Investigations of photolysis and rebinding kinetics in myoglobin using proximal ligand replacements.

    abstract::We use laser flash photolysis and time-resolved Raman spectroscopy of CO-bound H93G myoglobin (Mb) mutants to study the influence of the proximal ligand on the CO rebinding kinetics. In H93G mutants, where the proximal linkage with the protein is eliminated and the heme can bind exogenous ligands (e.g., imidazole, 4-b...


    pub_type: 杂志文章


    authors: Cao W,Ye X,Sjodin T,Christian JF,Demidov AA,Berezhna S,Wang W,Barrick D,Sage JT,Champion PM

    更新日期:2004-08-31 00:00:00

  • Involvement of carboxy-terminal amino acids in secretion of human lysosomal protease cathepsin L.

    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...


    pub_type: 杂志文章


    authors: Chauhan SS,Ray D,Kane SE,Willingham MC,Gottesman MM

    更新日期:1998-06-09 00:00:00

  • "Dilysine trigger" in transferrins probed by mutagenesis of lactoferrin: crystal structures of the R210G, R210E, and R210L mutants of human lactoferrin.

    abstract::The mammalian iron-binding proteins lactoferrin (Lf) and transferrin (Tf) bind iron very tightly, but reversibly. Despite homologous structures and essentially identical iron binding sites, Tf begins to release iron at pH 6.0, whereas Lf retains iron to pH approximately 3.5. This difference in iron retention gives the...


    pub_type: 杂志文章


    authors: Peterson NA,Arcus VL,Anderson BF,Tweedie JW,Jameson GB,Baker EN

    更新日期:2002-12-03 00:00:00

  • Crystal structures of two self-hydroxylating ribonucleotide reductase protein R2 mutants: structural basis for the oxygen-insertion step of hydroxylation reactions catalyzed by diiron proteins.

    abstract::The R2 protein of ribonucleotide reductase catalyzes the dioxygen-dependent one-electron oxidation of Tyr122 at a diiron-carboxylate site. Methane monooxygenase and related hydroxylases catalyze hydrocarbon hydroxylation at diiron sites structurally related to the one in R2. In protein R2, the likely reaction site for...


    pub_type: 杂志文章


    authors: Logan DT,deMaré F,Persson BO,Slaby A,Sjöberg BM,Nordlund P

    更新日期:1998-07-28 00:00:00

  • Phosphonate analogues of carboxypeptidase A substrates are potent transition-state analogue inhibitors.

    abstract::Analogues of tri- and tetrapeptide substrates of carboxypeptidase A in which the scissile peptide linkage is replaced with a phosphonate moiety (-PO2--O-) were synthesized and evaluated as inhibitors of the enzyme. The inhibitors terminated with either L-lactate or L-phenyllactate [designated (O) Ala and (O) Phe, resp...


    pub_type: 杂志文章


    authors: Hanson JE,Kaplan AP,Bartlett PA

    更新日期:1989-07-25 00:00:00

  • Critical side-chain interactions at a subunit interface in the Arc repressor dimer.

    abstract::In the Arc repressor dimer, the side chains of Ile37 and Val41 in alpha-helix B pack against each other and against the symmetry-related side chains of Ile37' and Val41' in alpha-helix B' to form part of the hydrophobic core and the dimer interface. Following combinatorial mutagenesis of these positions, only the wild...


    pub_type: 杂志文章


    authors: Milla ME,Sauer RT

    更新日期:1995-03-14 00:00:00

  • Histidine residues at the N- and C-termini of alpha-helices: perturbed pKas and protein stability.

    abstract::A single histidine residue has been placed at either the N-terminus or the C-terminus of each of the two alpha-helices of barnase. The pKa of that histidine residue in each of the four mutants has been determined by 1H NMR. The pKas of the two residues at the C-terminus are, on average, 0.5 unit higher, and those of t...


    pub_type: 杂志文章


    authors: Sancho J,Serrano L,Fersht AR

    更新日期:1992-03-03 00:00:00

  • Mid- to low-frequency Fourier transform infrared spectra of S-state cycle for photosynthetic water oxidation in Synechocystis sp. PCC 6803.

    abstract::Flash-induced Fourier transform infrared (FTIR) difference spectra for the four-step S-state cycle and the effects of global (15)N- and (13)C-isotope labeling on the difference spectra were examined for the first time in the mid- to low-frequency (1200-800 cm(-1)) as well as the mid-frequency (1700-1200 cm(-1)) region...


    pub_type: 杂志文章


    authors: Yamanari T,Kimura Y,Mizusawa N,Ishii A,Ono TA

    更新日期:2004-06-15 00:00:00

  • Evolvability of thermophilic proteins from archaea and bacteria.

    abstract::Proteins from thermophiles possess high thermostability. The stabilization mechanisms differ between archaeal and bacterial proteins, whereby archaeal proteins are mainly stabilized via hydrophobic interactions and bacterial proteins by ion pairs. High stability is an important factor in promoting protein evolution, b...


    pub_type: 杂志文章


    authors: Takano K,Aoi A,Koga Y,Kanaya S

    更新日期:2013-07-16 00:00:00