Abstract：
:Escherichia coli asparagine synthetase B (AS-B) catalyzes the synthesis of asparagine from aspartate, glutamine, and ATP. A combination of kinetic, isotopic-labeling, and stoichiometry studies have been performed to define the nature of nitrogen transfer mediated by AS-B. The results of initial rate studies were consistent with initial binding and hydrolysis of glutamine to glutamate plus enzyme-bound ammonia. The initial velocity results were equally consistent with initial binding of ATP and aspartate prior to glutamine binding. However, product inhibition studies were only consistent with the latter pathway. Moreover, isotope-trapping studies confirmed that the enzyme-ATP-aspartate complex was kinetically competent. Studies using 18O-labeled aspartate were consistent with formation of a beta-aspartyl-AMP intermediate, and stoichiometry studies revealed that 1 equiv of this intermediate formed on the enzyme in the absence of a nitrogen source. Taken together, our results are most consistent with initial formation of beta -aspartyl-AMP intermediate prior to glutamine binding. This sequence leaves open many possibilities for the chemical mechanism of nitrogen transfer.
journal_name
Biochemistryjournal_title
Biochemistryauthors
Boehlein SK,Stewart JD,Walworth ES,Thirumoorthy R,Richards NG,Schuster SMdoi
10.1021/bi981058hsubject
Has Abstractpub_date
1998-09-22 00:00:00pages
13230-8issue
38eissn
0006-2960issn
1520-4995pii
bi981058hjournal_volume
37pub_type
杂志文章相关文献
BIOCHEMISTRY文献大全abstract：:Experimental and theoretical double-mutant cycles have been used to investigate a salt bridge in the N-terminal domain of the protein L9. Aspartic acid 23 is the only acidic residue involved in a well-defined pairwise interaction, namely, a partially solvent-exposed salt bridge with the protonated N-terminus of the pr...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi027202n
更新日期：2003-06-17 00:00:00
abstract：:The flavoprotein nitroalkane oxidase catalyzes the oxidation of primary and secondary nitroalkanes to aldehydes and ketones, respectively, transferring electrons to oxygen to form hydrogen peroxide. The steady-state kinetic mechanism of the active flavin adenine dinucleotide-(FAD-) containing form of the enzyme has be...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi9922547
更新日期：2000-02-15 00:00:00
abstract：:In prokaryotes, the first three enzymes in pyrimidine biosynthesis, carbamoyl phosphate synthetase (CPS), aspartate transcarbamoylase (ATC), and dihydroorotase (DHO), are commonly expressed separately and either function independently (Escherichia coli) or associate into multifunctional complexes (Aquifex aeolicus). I...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi801831r
更新日期：2009-02-03 00:00:00
abstract：:Pig liver phosphomevalonate kinase (EC 2.7.4.2) has been purified to homogeneity as shown by polyacrylamide gel electrophoresis. The molecular weight estimates range from 21,000 to 22,500. Each molecule is composed of one polypeptide chain. The presence of SH-containing reagents is essential for the preservation of en...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi00552a003
更新日期：1980-05-27 00:00:00
abstract：:Phosphorescent probes are described that are quenchable by dioxygen and that partition into membranes. These probes are derivatives of porphyrin, in which the central metal, either zinc or palladium, induces intersystem crossing to enhance the triplet yield. The location of the probe in a suspension of membranes depen...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi00474a018
更新日期：1990-06-05 00:00:00
abstract：:Monoclonal antibodies were raised against a mono-p-nitrophenyl phosphonate ester to elicit catalytic antibodies capable of hydrolyzing the analogous p-nitrophenyl ester or carbonate. Potential catalytic antibody producing clones were selected, by use of a competitive inhibition assay, on the basis of their affinity fo...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi00494a023
更新日期：1990-10-23 00:00:00
abstract：:Conventional isoforms of protein kinase C (PKC) are activated when their two membrane-targeting modules, the C1 and C2 domains, bind the second messengers diacylglycerol (DG) and Ca2+, respectively. This study investigates the mechanism of Ca2+-induced binding of PKC betaII to anionic membranes mediated by the C2 doma...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi010761u
更新日期：2001-11-06 00:00:00
abstract：:Hepatic microsomal NADPH-cytochrome P-450 reductase was solubilized from rabbit liver microsomes in the presence of detergents and purified to homogeneity by column chromatography. The purified reductase had a molecular weight of 78 000 and contained 1 mol each of FAD and FMN per mol of enzyme. On reduction with NADPH...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi00604a032
更新日期：1978-05-30 00:00:00
abstract：:Cations often deform the structure of regulatory proteins to affect a functional response, but for other protein functions a more passive effect is desired. For instance, it is shown here that in the conductance of Na+ by the gramicidin channel there appears to be no significant structural deformation of either the si...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi961170k
更新日期：1996-09-17 00:00:00
abstract：:Nitroalkane oxidase (NAO) from Fusarium oxysporum catalyzes the oxidation of neutral nitroalkanes to the corresponding aldehydes or ketones with the production of H(2)O(2) and nitrite. The flavoenzyme is a new member of the acyl-CoA dehydrogenase (ACAD) family, but it does not react with acyl-CoA substrates. We presen...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi051966w
更新日期：2006-01-31 00:00:00
abstract：:In the primary quinone (Q(A)) binding site of Rb. sphaeroides reaction centers (RCs), isoleucine M265 is in extensive van der Waals contact with the ubiquinone headgroup. Substitution of threonine or serine for this residue (mutants M265IT and M265IS), but not valine (mutant M265IV), lowers the redox midpoint potentia...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi026958j
更新日期：2003-04-15 00:00:00
abstract：:Equine chorionic gonadotropin (eCG) and lutropin (eLH) are composed of alpha- and beta-subunits with an identical amino acid sequence but show different biological activities. To elucidate the molecular difference between these gonadotropins, the structure of the N-linked oligosaccharides of each beta-subunit was dete...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi00251a012
更新日期：1994-11-29 00:00:00
abstract：:Purine C-8 tritium-labeling rates have been measured at specific sites in Escherichia coli tRNAIle and tRNA2Tyr. The results are compared with those obtained for yeast tRNAPhe (preceding paper(Gamble et al., 1976)). The tRNAIle and tRNAPhe fall into the same general class of tRNA structures, while tRNA2Tyr is in a dif...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi00658a015
更新日期：1976-06-29 00:00:00
abstract：:Baeyer-Villiger monooxygenases (BVMOs), mostly flavoproteins, were shown to be powerful biocatalysts for synthetic organic chemistry applications and were also suggested to play key roles for the biosyntheses of various natural products. Here we present the three-dimensional structure of MtmOIV, a 56 kDa homodimeric F...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi8023509
更新日期：2009-06-02 00:00:00
abstract：:Attenuated total reflection Fourier transform infrared (ATR-FTIR) difference spectroscopy has been performed on samples of bovine cytochrome c oxidase that have been deposited as a thin film on the surface of a silicon microprism. The technique has several advantages over transmission methods in terms of amount of mat...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi0109717
更新日期：2002-01-22 00:00:00
abstract：:The ionic and nucleotide requirements for the in vitro polymerization of microtubules from purified brain tubulin have been characterized by viscometry. Protein was purified by successive cycles of a temperature dependent assembly-diassembly scheme. Maximal polymerization occurred at a concentration of 0.1 M Pipes (pi...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi00684a032
更新日期：1975-07-01 00:00:00
abstract：:Apical membrane antigen 1 (AMA1) of the human malaria parasite Plasmodium falciparum is synthesized by schizont stage parasites and has been implicated in merozoite invasion of host erythrocytes. Phage-display techniques have recently been used to identify two 15-residue peptides, F1 and F2, which bind specifically to...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi034376b
更新日期：2003-08-26 00:00:00
abstract：:We have studied the transient kinetics of electron transfer from a positively charged viologen analogue (propylene diquat), reduced by pulsed laser excitation of the deazariboflavin/EDTA system, to the net negatively charged ferredoxins from spinach and Clostridium pasteurianum. Spinach ferredoxin showed monophasic ki...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi00440a050
更新日期：1989-07-11 00:00:00
abstract：:β-Lactamase inhibitors (BLIs) restore the efficacy of otherwise obsolete β-lactams. However, commercially available BLIs are not effective against metallo-β-lactamases (MBLs), which continue to be disseminated globally. One group of the most clinically important MBLs is the VIM family. The discovery of VIM-24, a natur...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/acs.biochem.5b00106
更新日期：2015-05-26 00:00:00
abstract：:S-Adenosylmethionine decarboxylase (AdoMetDC) is a key enzyme in the polyamine biosynthetic pathway. Inhibition of this pathway and subsequent depletion of polyamine levels is a viable strategy for cancer chemotherapy and for the treatment of parasitic diseases. Substrate analogue inhibitors display an absolute requir...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi900590m
更新日期：2009-07-14 00:00:00
abstract：:Here, we introduce the concept of the "seleno effect" in the study of oxidoreductases that catalyze thiol/disulfide exchange reactions. In these reactions, selenium can replace sulfur as a nucleophile, electrophile, or leaving group, and the resulting change in rate (the seleno effect) is defined as kS/ kSe. In soluti...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/acs.biochem.8b00004
更新日期：2018-03-20 00:00:00
abstract：:In an effort to gain greater insight into the molecular mechanism of the electron-transfer reactions of cytochrome b(5), the bovine cytochrome b(5)-horse cytochrome c complex has been investigated by high-resolution multidimensional NMR spectroscopy using (13)C, (15)N-labeled cytochrome b(5) expressed from a synthetic...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi001129o
更新日期：2000-11-21 00:00:00
abstract：:We have previously shown functional differences in fibrinogen from hyperhomocysteinemic rabbits compared to that in control rabbits. This acquired dysfibrinogenemia is characterized by fibrin clots that are composed of abnormally thin, tightly packed fibers with increased resistance to fibrinolysis. Homocysteine thiol...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi052076j
更新日期：2006-02-28 00:00:00
abstract：:In this study, we have investigated the effect of hydrophobic mismatch between the thickness of the membrane and a transmembrane segment of a protein that directly inserts into the membrane bilayer. For this purpose we used mutants of the single-spanning Pf3 coat protein that can spontaneously insert into Escherichia ...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi0158674
更新日期：2002-04-16 00:00:00
abstract：:Hydrogen bonds which form between a hydrogen bond donor and an aromatic ring as acceptor are thought to contribute to the stability and function of proteins. We have tested the function of such an interaction in a highly homologous pair of proteins, cellular retinol-binding protein (CRBP) and cellular retinol-binding ...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi00035a018
更新日期：1995-09-05 00:00:00
abstract：:A soluble Ca2+/calmodulin-dependent protein kinase has been purified from rat brain to near homogeneity by using casein as substrate. The enzyme was purified by using hydroxylapatite adsorption chromatography, phosphocellulose ion-exchange chromatography, Sepharose 6B gel filtration, affinity chromatography using calm...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi00318a018
更新日期：1984-11-06 00:00:00
abstract：:An OxlT homology model suggests R272 and K355 in transmembrane helices 8 and 11, respectively, are critical to OxlT-mediated transport. We offer positive evidence supporting this idea by studying OxlT function after cysteine residues were separately introduced at these positions. Without further treatment, both mutant...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi060746v
更新日期：2006-08-29 00:00:00
abstract：:Solvent reorganization can contribute significantly to the energetics of protein-protein interactions. However, our knowledge of the magnitude of the energetic contribution is limited, in part, by a dearth of quantitative experimental measurements. The biotin repressor forms a homodimer as a prerequisite to DNA bindin...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi400952m
更新日期：2013-09-24 00:00:00
abstract：:Translation of mRNAs by the ribosome is stereospecific, with only l-amino acids being incorporated into the nascent polypeptide chain. This stereospecificity results from the exclusion of d-amino acids at three steps during protein synthesis: (1) the aminoacylation of tRNA by aminoacyl-tRNA synthetases, (2) binding of...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/acs.biochem.5b01167
更新日期：2016-03-15 00:00:00
abstract：:The 5'-untranslated region of positive-strand RNA viruses harbors many cis-acting RNA structural elements that are important for various viral processes such as replication, translation, and packaging of new virions. Among these is loop B RNA of the stem-loop IV domain within the internal ribosomal entry site (IRES) o...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi0363228
更新日期：2004-05-18 00:00:00
