Abstract：
:Human apolipoprotein stimulation of sphingomyelin (SM) hydrolysis by sphingomyelinase from human skin fibroblasts has been studied. Apolipoproteins A-I, A-II, B, C-I, and E do not enhance sphingomyelin hydrolysis above control levels. In contrast, apoC-II stimulates sphingomyelin hydrolysis by approximately 2.5-fold. ApoC-III, the most potent apoprotein activator, stimulates hydrolysis by 3-4-fold. ApoC-III stimulation is not significantly different for the three different isoforms which carry 0, 1, or 2 sialic acid residues. The amino-terminal half of this apoprotein, C-III(1-40), which does not bind to phospholipid surfaces, does not activate sphingomyelinase. In contrast, the carboxyl-terminal half, C-III(41-79), which strongly binds to phospholipid surfaces, stimulates sphingomyelin hydrolysis to the same level as that produced by the intact, full-length apoprotein. Incubation of sphingomyelin vesicles with increasing proportions of apoC-III results in the formation of complexes of increasing apoC-III:SM ratio and decreasing radius. The hydrolysis of sphingomyelin in the 1:50 (mol/mol) complex was more than 2-fold greater than that of the 1:200 (mol/mol) complex. The rate of hydrolysis of egg yolk sphingomyelin in the 1:50 complex was maximal [0.9 mumol h-1 (mg of protein)-1] at the gel----liquid-crystalline phase transition temperature (Tm) of the complex (40 degrees C). The rate of hydrolysis fell markedly at either higher or lower temperature. Determination of the apparent Km and Vmax values below, at, and above Tm indicated that the temperature dependence of sphingomyelin hydrolysis was attributable primarily to changes in Vmax.(ABSTRACT TRUNCATED AT 250 WORDS)
journal_name
Biochemistryjournal_title
Biochemistryauthors
Ahmad TY,Beaudet AL,Sparrow JT,Morrisett JDdoi
10.1021/bi00363a036subject
Has Abstractpub_date
1986-07-29 00:00:00pages
4415-20issue
15eissn
0006-2960issn
1520-4995journal_volume
25pub_type
杂志文章相关文献
BIOCHEMISTRY文献大全abstract：:Although tryptophan synthase catalyzes a number of pyridoxal phosphate dependent beta-elimination and beta-replacement reactions that are also catalyzed by tryptophanase, a principal and puzzling difference between the two enzymes lies in the apparent inability of tryptophan synthase to catalyze beta-elimination of in...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi00363a010
更新日期：1986-07-29 00:00:00
abstract：:Drosophila Rrp1 includes a carboxy-terminal region homologous to Escherichia coli exonuclease III which is sufficient to repair both oxidative and alkylation damage to DNA. An apurinic/apyrimidinic endonuclease activity intrinsic to Rrp1 was characterized previously. In this work, the 3'-phosphodiesterase and 3'-phosp...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi00004a021
更新日期：1995-01-31 00:00:00
abstract：:The formation of closed icosahedral capsids from a single species of coat protein subunit requires that the subunits assume different conformations at different lattice positions. In the double-stranded DNA bacteriophage P22, formation of correctly dimensioned capsids is mediated by interaction between coat protein su...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi00475a030
更新日期：1990-06-12 00:00:00
abstract：:In cerebellum, inositol trisphosphate- (InsP(3)-) gated Ca channels play a key role in learning, though they exhibit a low sensitivity to InsP(3) compared to peripheral tissues. In the present study, the cerebellar InsP(3) receptor is shown to be associated with a novel inhibitor of InsP(3) binding. (3)H-InsP(3) bindi...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi992175v
更新日期：2000-03-28 00:00:00
abstract：:Carboxylation of vitamin K-dependent (VKD) proteins is required for their activity and depends on reduced vitamin K generated by vitamin K oxidoreductase (VKOR) and a redox protein that regenerates VKOR activity. VKD protein carboxylation is inefficient in mammalian cells, and to understand why carboxylation becomes s...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi051986y
更新日期：2006-05-02 00:00:00
abstract：:The solution structure of the dicerium(III) complex of the N-terminal domain of calmodulin (Ce2-TR1C hereafter) has been solved employing paramagnetic T1 relaxation enhancements and pseudocontact shifts introduced by the Ce3+ ions, together with conventional NOE constraints. The use of pseudocontact shift constraints ...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi971022+
更新日期：1997-09-30 00:00:00
abstract：:Gramicidin crystals, dimyristoylphosphatidylcholine (DMPC)/gramicidin dispersions, and DMPC/gramicidin cocrystals were examined by Raman scattering to determine lipid/gramicidin stoichiometries and lipid organization. Calibrations of the choline (716-cm-1) and tryptophan (756-cm-1) peaks indicate that the cocrystals c...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi00376a030
更新日期：1987-01-27 00:00:00
abstract：:Ultraviolet (uv)-light-mediated formation of protein-DNA adducts in Chinese hamster cell chromatin was investigated in an attempt to compare chromatin alterations induced in vitro with those observed in vivo. Three independent methods of analysis indicated stable protein-DNA associations: (1) a membrane filter assay w...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi00653a019
更新日期：1976-04-20 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：:A Ca(2+)-activated thiol protease was purified from Drosophila melanogaster. The procedure involves Phenyl-Sepharose, Reactive Red-Agarose and Q-Sepharose fast flow (or MonoQ) chromatographic steps. The enzyme eluting from Q-Sepharose fast flow seems to be homogeneous as judged by silver staining on SDS-PAGE: it consi...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi00150a012
更新日期：1992-09-08 00:00:00
abstract：:Evidence is presented that indicates tropoelastin is derived from a soluble elastin with a molecular weight of 95000. Tropoelastin and its proposed precursor were isolated from the aortas of copper-deficient chicks. Although it is doubtful that the proposed precursor is an initial product of elastin translation, i.e.,...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi00585a004
更新日期：1979-09-04 00:00:00
abstract：:Many lipases are potent catalysts of stereoselective reactions and are therefore of interest for use in chemical synthesis. The crystal structures of lipases show a large variation in the shapes of their active site environments that may explain the large variation in substrate specificity of these enzymes. We have de...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi00051a035
更新日期：1995-12-26 00:00:00
abstract：:Solvent kinetic isotope effect studies of electron transfer within xanthine oxidase have been performed, using a stopped-flow pH-jump technique to perturb the distribution of reducing equivalents within partially reduced enzyme and follow the kinetics of reequilibration spectrophotometrically. It is found that the rat...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi00099a004
更新日期：1991-09-03 00:00:00
abstract：:The interactions of Alzheimer's amyloid beta-peptide with cyclodextrins were studied by (1)H NMR: the translational diffusion coefficient of the peptide and chemical shift changes were studied by the presence of variable concentrations of cyclodextrins. For the full-length peptide, Abeta(1-40), the combined results of...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi036254p
更新日期：2004-05-25 00:00:00
abstract：:In bacteria, the transcription of virulence genes is usually controlled by a cell density-dependent process known as "quorum sensing" (QS). QS relies on small diffusible signaling molecules that cross the bacterial cell wall and activate target transcription factors after a threshold concentration has been reached. Be...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi900123j
更新日期：2009-11-03 00:00:00
abstract：:Unfractionated Escherichia coli tRNA has been aminoacylated with lysine and preferentially acetylated at the epsilon-amino nitrogen of lysine by reaction with N-acetoxysuccinimide. After treatment with peptidyl-tRNA hydrolase, 90% of the aminoacylated tRNA molecules were Nepsilon-acetyl-Lys-tRNA. Post-ribosomal supern...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi00648a018
更新日期：1976-02-10 00:00:00
abstract：:To understand the mechanism by which annexin I induces membrane aggregation, a comprehensive mutagenesis of all six Ca2+-binding sites was performed. When the cap residues of type II Ca2+-binding sites were systematically mutated to Ala, a type II site in domain II was shown to be essential for Ca2+-dependent vesicle ...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi980479w
更新日期：1998-07-14 00:00:00
abstract：:Cytochrome P450 3A4 is a drug-metabolizing enzyme of extraordinarily broad substrate specificity. This quality imparts upon the enzyme special importance in understanding its determinants of activity and substrate recognition. Limited successes in P450 3A4 active-site structure studies have been achieved by use of mec...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi049231z
更新日期：2005-02-15 00:00:00
abstract：:The nuclease hypersensitivity element III(1) (NHE III(1)) of the c-MYC promoter strongly controls the transcriptional activity of the c-MYC oncogene. The purine-rich strand of the NHE III(1) element has been shown to be a silencer element for c-MYC transcription upon formation of a G-quadruplex structure. We have dete...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi048242p
更新日期：2005-02-15 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：:ATP-binding cassette (ABC) transporters are ubiquitous in all three kingdoms of life and are implicated in many clinically relevant physiological processes. They couple the energy released by ATP hydrolysis to facilitate substrate translocation across cell membranes. The crystal structures of type II ABC importers hav...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/acs.biochem.6b00386
更新日期：2016-12-13 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：:The aminoglycoside 6'-N-acetyltransferase AAC(6')-Ii from Enterococcus faecium is an important microbial resistance determinant and a member of the GCN5-related N-acetyltransferase (GNAT) superfamily. We report here the further characterization of this enzyme in terms of the kinetic mechanism of acetyl transfer and id...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi034148h
更新日期：2003-06-03 00:00:00
abstract：:Herpesvirus saimiri codes for a tyrosine kinase interacting protein (Tip) that interacts with both the SH3 domain and the kinase domain of the T-cell-specific tyrosine kinase Lck via two separate motifs. The activation of Lck by Tip is considered as a key event in the transformation of human T-lymphocytes during herpe...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi015986j
更新日期：2002-04-23 00:00:00
abstract：:Specific lysine residues on the ubiquitin surface were selected during the course of evolution to form different polyubiquitin chain structures that signal diverse cellular processes. A vast number of ubiquitin receptors specifically recognize and decode the signals conferred by these polyubiquitin chains. The mechani...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/acs.biochem.5b00498
更新日期：2015-08-04 00:00:00
abstract：:The Na(+)-pumping NADH:quinone oxidoreductase (Na(+)-NQR) is a fundamental enzyme of the oxidative phosphorylation metabolism and ionic homeostasis in several pathogenic and marine bacteria. To understand the mechanism that couples electron transfer with sodium translocation in Na(+)-NQR, the ion dependence of the red...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi300343u
更新日期：2012-05-15 00:00:00
abstract：:The mitochondrial tyrosyl tRNA synthetase from Neurospora crassa (CYT-18 protein) is a bifunctional group I intron splicing cofactor. CYT-18 is capable of splicing multiple group I introns from a wide variety of sources by stabilizing the catalytically active intron structures. CYT-18 and mt TyrRSs from related fungal...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi401614h
更新日期：2014-03-04 00:00:00
abstract：:Indolamine N-methyltransferase (INMT) has been purified to an apparent homogeneity from rabbit lung, and some of its catalytic and physicochemical properties have been examined. The enzyme is a monomeric protein with a molecular weight of 31,500 +/- 1000, a molecular Stokes radius of 21.5 A, and a diffusion coefficien...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi00535a054
更新日期：1982-03-16 00:00:00
abstract：:We have measured the microsecond rotational motions of myosin heads in contracting rabbit psoas muscle fibers by detecting the transient phosphorescence anisotropy of eosin-5-maleimide attached specifically to the myosin head. Experiments were performed on small bundles (10-20 fibers) of glycerinated rabbit psoas musc...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi00495a003
更新日期：1990-10-30 00:00:00
abstract：:Recently, we described the formation of a complex between liposomes and the unfolded protein rhodanese (thiosulfate:cyanide sulfurtransferase, EC 2.8.1.1), which could be liberated and efficiently reactivated after treatment of the complex with detergents [Zardeneta, G., & Horowitz, P. M. (1992) Eur. J. Biochem. 210, ...
journal_title：Biochemistry
pub_type： 杂志文章
doi：10.1021/bi00213a025
更新日期：1993-12-21 00:00:00
