Abstract：
:The molecular mechanism of hemoglobin cooperativity was studied kinetically by flash photolysis on mixed-state hemoglobins which consist of three ferrous carboxy subunits and one hybrid ferric subunit including fluoromet, azidomet, cyanatomet, and thiocyanatomet. The effects of conformational transitions on the hybrid subunit were detected by kinetic absorption spectroscopy after the CO was fully photodissociated from the binding sites by a large pulse of light from a tunable dye laser. The hemoglobin conformational transition rate was observed to depend on its state of ligation. At 22 degrees C, pH 7, and 0.1 M phosphate, the deoxy R yields T conformational change rate is 4 x 10(4)s-1. The rate decreases to 1.4 x 10(4)s-1 for singly ligated hemoglobin. The R yields T conformation change alters the energy separation between high- and low-spin states for azidomet, cyanatomet, and thiocyanatomet subunits by about 700, 300, and 300 cal/mol, respectively. There are two possible implications of this result: (1) the iron atom spin state is not the only major factor in the determination of its position with respect to the heme plane or (2) the change with conformation of the protein force exerted by the proximal histidine on the iron atom (for an iron to heme-plane displacement of less than 0.3 A) is less than 50% of that expected from simple models in which this motion is responsible for cooperativity.
journal_name
Biochemistryjournal_title
Biochemistryauthors
Cho KC,Hopfield JJdoi
10.1021/bi00593a012subject
Has Abstractpub_date
1979-12-25 00:00:00pages
5826-33issue
26eissn
0006-2960issn
1520-4995journal_volume
18pub_type
杂志文章相关文献
BIOCHEMISTRY文献大全abstract：:Photoactive yellow proteins (PYPs) make up a diverse class of blue-light-absorbing bacterial photoreceptors. Electronic excitation of the p-coumaric acid chromophore covalently bound within PYP results in triphasic quenching kinetics; however, the molecular basis of this behavior remains unresolved. Here we explore th...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/acs.biochem.7b01114
更新日期：2018-03-20 00:00:00
abstract：:Arginine 54 in subunit I of cytochrome c oxidase from Paracoccus denitrificans interacts with the formyl group of heme a. Mutation of this arginine to methionine (R54M) dramatically changes the spectral properties of heme a and lowers its midpoint redox potential [Kannt et al. (1999) J. Biol. Chem. 274, 37974-37981; L...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi002948b
更新日期：2001-05-01 00:00:00
abstract：:Vibrational circular dichroism (VCD) and Fourier transform IR (FTIR) were measured for a series of short alanine-based peptides having the general formula Ac-(AAKAA)n-GY-NH2 (n = 1-4) from 5 to 50 degrees C in D2O and at room temperature in both TFE and H2O. In both of these latter solvents, the dominant structural fo...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi971460g
更新日期：1997-12-09 00:00:00
abstract：:Atomic force microscopy (AFM) is a technique widely used to image protein-DNA complexes, and its application has now been extended to the measurements of protein-DNA binding constants and specificities. However, the spreading of the protein-DNA complexes on a flat substrate, generally mica, is required prior to AFM im...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi060293u
更新日期：2006-12-12 00:00:00
abstract：:Unoccupied estrogen receptor (ER) can be extracted from tissues by homogenization with a hypotonic buffer, whereas hormone-occupied ER becomes tightly bound to the nuclear pellet and must be extracted with high-salt-containing buffers. The molecular basis for estrogen-induced tight nuclear binding of ER remains an imp...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi982190k
更新日期：1999-06-01 00:00:00
abstract：:The gene 5 protein (g5p) encoded by filamentous Ff phages is an ssDNA-binding protein, which binds to and sequesters the nascent ssDNA phage genome in the process of phage morphogenesis. The g5p also binds with high affinity to DNA and RNA sequences that form G-quadruplex structures. However, sequences that would form...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi030177g
更新日期：2004-03-09 00:00:00
abstract：:Lipocortin I is a 39-kilodalton membrane-associated protein that in A431 cells is phosphorylated on tyrosine in response to epidermal growth factor (EGF). We have used recombinant human lipocortin I as a substrate for several protein kinases and identified phosphorylated residues by a combination of peptide mapping an...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi00410a024
更新日期：1988-05-17 00:00:00
abstract：:Excitation energy transfer studies were carried out to determine the distance between the adenosinetriphosphatase (ATPase) site and a unique "fast-reacting" sulfhydryl (referred to as SH1) in myosin subfragment 1. The fluorescent moiety of the probe N-(iodoacetyl)-N'-(5-sulfo-1-naphthyl)ethylene-diamine was used as th...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi00520a035
更新日期：1981-08-18 00:00:00
abstract：:Glutamate racemase, MurI, catalyzes the interconversion of glutamate enantiomers in a cofactor-independent fashion and provides bacteria with a source of D-Glu for use in peptidoglycan biosynthesis. The enzyme uses a "two-base" mechanism involving a deprotonation of the substrate at the alpha-position to form an anion...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi002703z
更新日期：2001-05-29 00:00:00
abstract：:The envelope glycoprotein (G protein) of vesicular stomatitis virus probably exists in the viral envelope as a trimer of identical subunits. Depending on the conditions of solubilization, G protein may dissociate into monomers. G protein solubilized with the detergent octyl glucoside was shown to exist as oligomeric f...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi00462a002
更新日期：1990-03-13 00:00:00
abstract：:hTom20 is an outer mitochondrial membrane receptor involved in protein translocation. The cytosolic domain (aa30-145) and selected truncated versions of this domain were overexpressed and purified to study the structure-function relationship of this protein. Our studies reveal that the secondary structure of the cytos...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi980746y
更新日期：1998-09-22 00:00:00
abstract：:Directed hydroxyl radical probing of 16S ribosomal RNA from Fe(II) tethered to specific sites within the RNA was used to determine RNA-RNA proximities in 70S ribosomes. We have transcribed 16S ribosomal RNA in vitro as two separate fragments, covalently attached an Fe(II) probe to a 5'-guanosine-alpha-phosphorothioate...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi981644a
更新日期：1999-01-19 00:00:00
abstract：:Aminoacylation of tRNA by aminoacyl-tRNA synthetases is the essential reaction that matches protein amino acids with the trinucleotide sequences specified in mRNA. Direct electrostatic interactions made by tRNA synthetases with discriminating functional groups on the tRNA bases have long been known to determine aminoa...
journal_title：Biochemistry
pub_type： 杂志文章,评审
doi：10.1021/bi7014647
更新日期：2007-09-18 00:00:00
abstract：:The oxycomplexes (compound III, oxyperoxidase) of two lignin peroxidase isozymes, H1 (pI = 4.7) and H8 (pI = 3.5), were characterized in the present study. After generation of the ferroperoxidase by photochemical reduction with deazoflavin in the presence of EDTA, the oxycomplex is formed by mixing ferroperoxidase wit...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi00460a018
更新日期：1990-02-27 00:00:00
abstract：:Bacterial L-asparaginases, enzymes that catalyze the hydrolysis of L-asparagine to aspartic acid, have been used for over 30 years as therapeutic agents in the treatment of acute childhood lymphoblastic leukemia. Other substrates of asparaginases include L-glutamine, D-asparagine, and succinic acid monoamide. In this ...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi0029595
更新日期：2001-05-15 00:00:00
abstract：:The catalytic (C) subunit of cAMP-dependent protein kinase interacts with two classes of inhibitors. The regulatory (R) subunits, types I and II, associate to form an inactive holoenzyme complex that is activated in response to cAMP. The C-subunit is also inhibited by small heat-stable protein kinase inhibitors (PKI's...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi00213a035
更新日期：1993-12-21 00:00:00
abstract：:Rhodospirillum rubrum ribulose bisphosphate carboxylase contains two high affinity binding sites for pyridoxal phosphate and two catalytic sites per dimer. However, pyridoxal phosphate binding at only one site is sufficient for inactivation of both catalytic sites. In the presence of 20 mM bicarbonate, 10 mM magnesium...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi00600a024
更新日期：1978-04-04 00:00:00
abstract：:The interaction of linker histone H1 with both linear and superhelical double-stranded DNA has been investigated at low ionic strengths. Gel mobility retardation experiments demonstrate strikingly different behavior for the two forms of DNA. First, the experiments strongly suggest that linker histone binds to superhel...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi0497704
更新日期：2004-06-22 00:00:00
abstract：:The membrane-bound closed channel structure of helices 4 and 5 (Lys-406-Asp-446) of the colicin E1 channel domain was investigated by using a site-directed fluorescence labeling technique. A bimane probe was covalently attached to a cysteine residue in a series of single-cysteine mutant proteins to scan each helix in ...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi801906v
更新日期：2009-02-17 00:00:00
abstract：:Physicochemical properties of recombinant human erythropoietin were examined. This protein, produced in Chinese hamster ovary cells, showed a conformation apparently identical with the natural product isolated from human urine when examined by circular dichroism, UV absorbance, and fluorescence spectroscopy. Sedimenta...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi00383a034
更新日期：1987-05-05 00:00:00
abstract：:The activity of the major isoform of porcine pancreatic phospholipase A2 (PLA2), designated B-PLA2, against micellar substrates is inhibited by heparin. Inhibition is a consequence of binding of the enzyme to heparin, documented by a heparin-induced alteration in the intrinsic fluorescence of B-PLA2 and in the 8-anili...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi00101a026
更新日期：1991-09-17 00:00:00
abstract：:The DNA binding domain of the yeast transcription factor Mbp1 is a winged helix-turn-helix structure, with an extended DNA binding site involving C-terminal "tail" residues. The thermodynamics of the interaction of the DNA binding domain with its target DNA sequence have been determined using fluorescence anisotropy a...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi702339q
更新日期：2008-06-17 00:00:00
abstract：:Vitamin E is a dietary lipid that is essential for vertebrate health and fertility. The biological activity of vitamin E is thought to reflect its ability to quench oxygen- and carbon-based free radicals and thus to protect the organism from oxidative damage. However, recent reports suggest that vitamin E may also dis...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi701432q
更新日期：2008-01-15 00:00:00
abstract：:The orientation of the myosin neck was monitored using electron paramagnetic resonance (EPR) spectroscopy. Gizzard regulatory light chain was labeled with a nitroxide spin probe and exchanged for the native subunit, located in the myosin neck, in rabbit psoas muscle fibers. The EPR spectra of rigor fibers indicated a ...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi960505v
更新日期：1996-08-06 00:00:00
abstract：:Matrix metalloproteinase-13 (MMP-13) is important in the pathology of osteoarthritis (OA). Although MMP-13 is considered a therapeutic target for OA, it is unclear how MMP-13 activity is regulated by the system that comprises various proteinases and their inhibitors. MMP-13 neutralizing antibodies could be a useful to...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi301228d
更新日期：2012-11-06 00:00:00
abstract：:The membrane-bound quinoprotein glucose dehydrogenase (mGDH) in Escherichia coli contains pyrroloquinoline quinone (PQQ) and participates in the direct oxidation of D-glucose to D-gluconate by transferring electrons to ubiquinone (UQ). To elucidate the mechanism of ubiquinone reduction by mGDH, we applied a pulse radi...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi051347n
更新日期：2005-10-18 00:00:00
abstract：:We have used nucleoside phosphorothioates (NTP alpha S) and a substitution-interference method to identify phosphate oxygens that appear to be important to guanosine cofactor addition in the self-splicing group I intron from Tetrahymena thermophila. For the majority of these phosphate oxygens, however, the effect of N...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi00068a001
更新日期：1993-05-04 00:00:00
abstract：:Reactivation of organophosphate (OP)-inhibited acetylcholinesterase (AChE) is a key objective in the treatment of OP poisoning. This study with native, wild-type, and mutant recombinant DNA-expressed AChEs, each inhibited by representative OP compounds, establishes a relationship between edrophonium acceleration of ox...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi9905720
更新日期：1999-08-03 00:00:00
abstract：:The flexibility of individual amino acid side chains of pancreatic phospholipase A2 in aqueous and micellar solutions was studied with deuterium nuclear magnetic resonance (2H NMR). Bovine pancreatic phospholipase A2 was selectively deuterated at the aromatic ring systems of Trp-3 and Phe-5 and porcine pancreatic phos...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi00334a029
更新日期：1985-06-18 00:00:00
abstract：:Reaction of 1-oxiranylpyrene (1-OP) with DNA and the structures of the covalent and noncovalent complexes formed were studied in aqueous media (5 mM phosphate buffer with 0.1 M NaCl, pH 7) by utilizing the techniques of absorption, fluorescence and linear dichroism spectroscopy in order to gain an understanding of pos...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi00318a009
更新日期：1984-11-06 00:00:00
