Abstract：
:The cofactor product of the aromatic amino acid hydroxylases, 4a-hydroxy-6(R)-tetrahydrobiopterin, requires dehydration before tetrahydrobiopterin can be regenerated by dihydropteridine reductase. Carbinolamine dehydration occurs nonenzymatically, but the reaction is also catalyzed by 4a-hydroxytetrahydropterin dehydratase. This enzyme has the identical amino acid sequence to DCoH, the dimerization cofactor of the transcription regulator, HNF-1 alpha. The catalytic activity of rat liver dehydratase was characterized using a new assay employing chemically synthesized 4a-hydroxytetrahydropterins. The enzyme shows little sensitivity to the structure or configuration of the 6-substituent of its substrate, with Km's for 6(S)-methyl, 6(R)-methyl, 6(S)-propyl, and 6(R)-L-erythro-dihydroxypropyl all between 1.5 and 6 microM. Turnover numbers at 37 degrees C are 50-90 s-1 at pH 7.4 and 2.5-3-fold lower at pH 8.4. Both 4a(R)- and 4a(S)-hydroxytetrahydropterins are good substrates. The quinoid dihydropterin products are strong inhibitors of the dehydratase with KI's about one half of their respective Km's, but no inhibition was observed with 7,8-dihydropterins or tetrahydropterins. The enzyme contains no metals and no phosphorus. Reaction mechanisms which involve either acid and/or base catalysis are discussed. 4a-Hydroxy-6(R)-tetrahydrobiopterin was determined not to be a product inhibitor of phenylalanine hydroxylase. It is concluded that the dehydratase (which was found to be 6 microM in rat liver) is essential in vivo to prevent rearrangement of 4a-hydroxy-6(R)-tetrahydrobiopterin and to maintain the supply of tetrahydrobiopterin cofactor for the hydroxylases under conditions where the nonenzymatic rate would be inadequate.
journal_name
Biochemistryjournal_title
Biochemistryauthors
Rebrin I,Bailey SW,Boerth SR,Ardell MD,Ayling JEdoi
10.1021/bi00017a011subject
Has Abstractpub_date
1995-05-02 00:00:00pages
5801-10issue
17eissn
0006-2960issn
1520-4995journal_volume
34pub_type
杂志文章相关文献
BIOCHEMISTRY文献大全abstract：:Protein S is an anticoagulant protein containing a Gla (enclosing gamma-carboxyglutamic acids) module, a TSR (thrombin sensitive region) module, four EGF (epidermal growth factor)-like modules, and a SHBG (sex hormone binding globulin)-like region. Protein S is a cofactor to activated protein C (APC) in the degradatio...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi0601151
更新日期：2006-09-05 00:00:00
abstract：:RNAs are involved in myriad cellular events. In general, RNA function is affected by cellular conditions. For instance, molecular crowding promotes RNA folding through compaction of the RNA. Metabolites generally destabilize RNA secondary structure, which improves RNA folding cooperativity and increases the fraction o...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/acs.biochem.9b00578
更新日期：2019-09-24 00:00:00
abstract：:Rapid withdrawal of estrogen from immature chicks, previously stimulated with the hormone, results in the inhibition of transcription of mRNAs of egg white proteins, rapid degradation of existing estrogen-induced mRNAs of egg white proteins, and decline in ribosomes and weight of the oviduct. On rapid withdrawal of es...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi00409a019
更新日期：1988-05-03 00:00:00
abstract：:The specific effect of the binding of IF2 and initiator fMET-tRNA(fMet) on Escherichia coli 16S rRNA has been probed by phosphate alkylation with ethylnitrosourea. The results show that IF2 does not significantly shield portions of 16S rRNA but induces both reductions and enhancements of reactivity scattered in the en...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi00487a023
更新日期：1990-09-04 00:00:00
abstract：:Dihydrofolate and dihydropteroylpolyglutamates inhibit pig liver methylenetetrahydrofolate reductase. In all cases the inhibition is linearly competitive with respect to methylenetetrahydrofolate. The Ki values decrease with each additional glutamyl residue from one to six, from a value of 6.5 microM for dihydrofolate...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi00551a005
更新日期：1980-05-13 00:00:00
abstract：:Synthetic nonviral vector systems are attractive because of their apparent simplicity of preparation and use. However, there are many barriers to success at the moment, including the formulation of uniform and reproducible particles of transfection competent, condensed nucleic acids such as plasmid DNA (pDNA). For thi...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi034325e
更新日期：2003-09-09 00:00:00
abstract：:The peptides generated from the degradation of the oxidized B chain of bovine insulin by the multiproteinase complex macropain (proteasome) have been analyzed by reverse-phase peptide mapping and identified by N-terminal amino acid sequencing and composition analysis. Six of the 29 peptide bonds in the insulin B chain...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi00224a022
更新日期：1991-03-12 00:00:00
abstract：:The thermodynamic quantities of the anti-dinitrophenyl antibody-hapten interaction are reported for rabbit, goat, and guinea pig antibodies. Rabbit and goat antibodies had similar exothermic enthalpy changes for their reaction with 2,4-dinitrophenyl-L-lysine (-13.9 and -14.8 kcal/mol, respectively). The enthalpy chang...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi00694a032
更新日期：1975-11-18 00:00:00
abstract：:We have examined the effects on redox kinetics of changing the reduction potential of the mu-oxo-bridged binuclear iron center in octameric hemerythrin (Hr) from Phascolopsis gouldii. The opportunity to examine such effects is provided by the availability of mu-sulfidomethemerythrin (mu-S2-metHr), whose [Fe(III),Fe(II...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi00400a033
更新日期：1987-12-29 00:00:00
abstract：:A heterologous expression system was used to evaluate activation of BlaR1, a sensor/signal transducer protein of Staphylococcus aureus with a central role in resistance to β-lactam antibiotics. In the absence of other S. aureus proteins that might respond to antibiotics and participate in signal transduction events, w...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi300429p
更新日期：2012-06-12 00:00:00
abstract：:Fragment-based approaches to finding novel small molecules that bind to proteins are now firmly established in drug discovery and chemical biology. Initially developed primarily in a few centers in the biotech and pharma industry, this methodology has now been adopted widely in both the pharmaceutical industry and aca...
journal_title：Biochemistry
pub_type： 杂志文章,评审
doi：10.1021/bi3005126
更新日期：2012-06-26 00:00:00
abstract：:Unilamellar liposomes can be fused at low pH with the plasma membrane of cells that express the hemagglutinin glycoprotein of influenza virus on their surface [van Meer, G., & Simons, K. (1983) J. Cell Biol. 97, 1365-1374]. Here, we have resolved this fusion process into two kinetically distinct steps. The first and m...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi00335a030
更新日期：1985-07-02 00:00:00
abstract：:In eukaryotic cells, chromatin is classified into euchromatin, which is active in transcription, and heterochromatin that silences transcription. Histones in these two domains contain distinct modifications. Chromatin assembly factor 1 (CAF-1) is a highly conserved protein that functions in DNA replication, DNA repair...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi0521083
更新日期：2006-03-07 00:00:00
abstract：:Protein folding in vivo takes place in a highly crowded environment. The resulting excluded volume forces are thought to stabilize folded forms of proteins. In agreement, many in vitro studies have shown that the presence of macromolecular crowding agents increases the stability of folded proteins but often by only a ...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi500222g
更新日期：2014-04-15 00:00:00
abstract：:Deazaflavins have been found to act as potent catalysts in the photoreduction of flavoproteins in the presence of EDTA and other "photosubstrates". In distinction to the catalysis brought about by normal flavins which involves dark reaction of the photoreduced flavin catalyst, the mechanism of the catalysis by deazafl...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi00594a002
更新日期：1978-01-10 00:00:00
abstract：:Illuminating Ca2+-depleted photosystem (PS) II membranes generated two new EPR signals at g = 11 and 15 by perpendicular and parallel polarization modes, respectively. Two turnovers of the oxygen evolving center (OEC) beyond the modified S2' state are required for the appearance of these signals. The formation of the ...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi972471c
更新日期：1998-03-03 00:00:00
abstract：:The trimeric main light-harvesting complex (LHC-II) is the only antenna complex of higher plants of which a high-resolution 3D structure has been obtained (Kühlbrandt, W., Wang, D., and Fujiyoshi, Y. (1994) Nature 367, 614-621) and which can be refolded in vitro from its components. Four different recombinant forms of...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi015875k
更新日期：2002-02-19 00:00:00
abstract：:The effect of the general anesthetics alpha-chloralose and chloral hydrate as well as the nonanesthetic beta-chloralose on the order of phosphatidylcholine and phosphatidylcholine-cholesterol liposomes has been examined by 2H nuclear magnetic resonance. Chloral hydrate interacts with the hydrophilic head-group region,...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi00346a019
更新日期：1985-12-03 00:00:00
abstract：:Calcium protects a limited number of embryonic chick neural retina cell surface proteins from tryptic cleavage. One glycoprotein of Mr approximately 1.3 X 10(5) and pI approximately 4.8 (gp130) is present in intact retinas and, in the presence of Ca2+, is both resistant to tryptic cleavage and poorly iodinated. When c...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi00300a016
更新日期：1984-02-28 00:00:00
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...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi972155y
更新日期：1997-12-23 00:00:00
abstract：:Specific binding of glutamate to its carrier was investigated by using cytoplasmic membrane vesicles prepared from Escherichia coli B. The binding activity was specifically affected by the Na+ and H+ concentrations of the medium. Cytoplasmic membrane vesicles from the mutant strain 36-39 that is defective in the Na+-d...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi00277a033
更新日期：1983-04-12 00:00:00
abstract：:A compound tentatively identified as O2-methyl-5-carboxymethyluridine (cm5Um) was recently isolated in this laboratory from bulk yeast transfer RNA (Gray, M. W. (1975), Can, J. Biochem. 53, 735-746). Alkaline hydrolysis of yeast tRNA releases this nucleoside as part of an alkali-stable dinucleotide, cm5Um-Ap, from whi...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi00659a017
更新日期：1976-07-13 00:00:00
abstract：:In refolding of iso-2 cytochrome c from Saccharomyces cerevisiae, there are two slow folding reactions, tau 1a and tau 1b. The slower of the slow reactions, tau 1a = 100-200 s, is observed only by absorbance changes, while tau 1b (10-20-fold faster) is detected by fluorescence changes. The temperature dependence of th...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi00348a024
更新日期：1985-12-31 00:00:00
abstract：:Single mutations of three amino acid residues in the vicinity of the primary electron donor, P, in the reaction center (RC) from Rhodobacter (Rb.) sphaeroides were constructed and characterized in order to study the effects of hydrogen-bonding on the physical properties of P. The mutations, Phe M197-->Tyr, Met L248-->...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi00210a041
更新日期：1993-11-30 00:00:00
abstract：:Transient phosphorylation at an aspartate residue on the Spo0F protein is a central step in the phosphorelay signal transduction pathway controlling sporulation in Bacilli. The response regulator Spo0F-P is stable to hydrolysis (t1/2 > 24 h at 23 degrees C in the absence of Mg2+), allowing the use of nondenaturing PAG...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi9519361
更新日期：1996-03-05 00:00:00
abstract：:A 39/34-kilodalton (kDa) monomeric dispase fragment of von Willebrand factor (vWF) has been purified by heparin affinity chromatography. Detailed structural analysis of the individual 39- and 34-kDa fragments indicated that they had identical amino acid sequences extending from Leu-480/Val-481 to Gly-718 with an intra...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi00447a010
更新日期：1989-10-17 00:00:00
abstract：:A highly sensitive and stable scanning microcalorimeter is employed in a reinvestigation of the effect of cholesterol on multilamellar suspensions of dimyristoylphosphatidylcholine (DMPC) and dipalmitoylphosphatidylcholine (DPPC). Below 20 mol % cholesterol the DPPC mixtures give heat-capacity curves each of which can...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi00605a034
更新日期：1978-06-13 00:00:00
abstract：:Structural changes in the complex formation between transducin and metarhodopsin II, the activated form of photolyzed rhodopsin, in visual transduction processes were analyzed by Fourier transform infrared spectroscopy. The spectrum of the complex was obtained by subtracting the contribution of metarhodopsin I and unc...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi960911e
更新日期：1996-10-15 00:00:00
abstract：:Isoaspartyl dipeptidase (IAD) is a member of the amidohydrolase superfamily and catalyzes the hydrolytic cleavage of beta-aspartyl dipeptides. Structural studies of the wild-type enzyme have demonstrated that the active site consists of a binuclear metal center positioned at the C-terminal end of a (beta/alpha)(8)-bar...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi050008r
更新日期：2005-05-17 00:00:00
abstract：:The structural features of a chemically modified DNA template strand may promote error-prone DNA synthesis during replication. The resulting higher incidence of mutations, in turn, can eventually lead to tumor initiation. Structural insights into this process can be monitored by studying chemically modified base adduc...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi00046a043
更新日期：1995-11-21 00:00:00
