Abstract:
:We investigated the effects of substituting two of the four tryptophans (the "inner pair" Trp(9) and Trp(11) or the "outer pair" Trp(13) and Trp(15)) in gramicidin A (gA) channels. The conformational preferences of the doubly substituted gA analogues were assessed using circular dichroism spectroscopy and size-exclusion chromatography, which show that the inner tryptophans 9 and 11 are critical for the gA's conformational preference in lipid bilayer membranes. [Phe(13,15)]gA largely retains the single-stranded helical channel structure, whereas [Phe(9,11)]gA exists primarily as double-stranded conformers. Within this context, the (2)H NMR spectra from labeled tryptophans were used to examine the changes in average indole ring orientations, induced by the Phe substitutions and by the shift in conformational preference. Using a method for deuterium labeling of already synthesized gAs, we introduced deuterium selectively onto positions C2 and C5 of the remaining tryptophan indole rings in the substituted gA analogues for solid-state (2)H NMR spectroscopy. The (least possible) changes in orientation and overall motion of each indole ring were estimated from the experimental spectra. Regardless of the mixture of backbone folds, the indole ring orientations observed in the analogues are similar to those found previously for gA channels. Both Phe-substituted analogues form single-stranded channels, as judged from the formation of heterodimeric channels with the native gA. [Phe(13,15)]gA channels have Na(+) currents that are ~50% and lifetimes that are ~80% of those of native gA channels. The double-stranded conformer(s) of [Phe(9,11)]gA do not form detectable channels. The minor single-stranded population of [Phe(9,11)]gA forms channels with Na(+) currents that are ~25% and single-channel lifetimes that are ~300% of those of native gA channels. Our results suggest that Trp(9) and Trp(11), when "reaching" for the interface, tend to drive both monomer folding (to "open" a channel) and dimer dissociation (to "close" a channel). Furthermore, the dipoles of Trp(9) and Trp(11) are relatively more important for the single-channel conductance than are the dipoles of Trp(13) and Trp(15).
journal_name
Biochemistryjournal_title
Biochemistryauthors
Gu H,Lum K,Kim JH,Greathouse DV,Andersen OS,Koeppe RE 2nddoi
10.1021/bi200136esubject
Has Abstractpub_date
2011-06-07 00:00:00pages
4855-66issue
22eissn
0006-2960issn
1520-4995journal_volume
50pub_type
杂志文章相关文献
BIOCHEMISTRY文献大全abstract::Nucleotide excision repair (NER) is a crucial pathway in the maintenance of genome stability requiring at least two dozen proteins. XPA and RPA have essential roles in the damage recognition step of NER. To better understand the mechanism of their interactions with DNA, we utilized equilibrium and stop-flow kinetic ap...
journal_title:Biochemistry
pub_type: 杂志文章
doi:10.1021/bi011041q
更新日期:2002-01-08 00:00:00
abstract::Actin depolymerizing activity in serum can be attributed to the two proteins brevin and vitamin D binding protein (DBP). To investigate their mechanisms of action, we used a number of techniques, including procedures involving the fluorescent pyrene-labeled actin probe, to compare the interaction of the two proteins w...
journal_title:Biochemistry
pub_type: 杂志文章
doi:10.1021/bi00308a030
更新日期:1984-06-19 00:00:00
abstract::Cyclopentenone prostanoids (cyP) arise as important modulators of inflammation and cell proliferation. Although their physiological significance has not been fully elucidated, their potent biological effects have spurred their study as leads for the development of therapeutic agents. A key determinant of cyP action is...
journal_title:Biochemistry
pub_type: 杂志文章
doi:10.1021/bi602389p
更新日期:2007-06-05 00:00:00
abstract::The S-protein/vitronectin gene was isolated from a human genomic DNA library, and its sequence of about 5.3 kilobases including the adjacent 5' and 3' flanking regions was established. Alignment of the genomic DNA nucleotide sequence and the cDNA sequence indicated that the gene consisted of eight exons and seven intr...
journal_title:Biochemistry
pub_type: 杂志文章
doi:10.1021/bi00395a024
更新日期:1987-10-20 00:00:00
abstract::Electron paramagnetic resonance studies have indicated that nitrosodisulfonate binds to pig heart citrate synthase. Titration of the enzyme with nitrosodisulfonate revealed several binding sites for the probe per subunit with one site (KD approximately 0.1 mM) having a greater affinity than the others. The substrate, ...
journal_title:Biochemistry
pub_type: 杂志文章
doi:10.1021/bi00584a028
更新日期:1979-08-21 00:00:00
abstract::Glycine oxidase gene from a strain of Bacillus subtilis was cloned and expressed in Escherichia coli. The purified enzyme was found, by mass spectrometry, to have a protein M(r) of 40763 (value of 40761.6 predicted from DNA sequence) and a FAD prosthetic group M(r) of 785.1 (theoretical value of 785.5). Glycine oxidas...
journal_title:Biochemistry
pub_type: 杂志文章
doi:10.1021/bi100553n
更新日期:2010-08-31 00:00:00
abstract::Annexin V is a Ca(2+)-dependent, phospholipid-binding protein that may have one or more membrane-related functions. The binding of annexin V to phospholipids in a detergent micelle matrix was studied to attempt to determine directly the stoichiometry of specific phospholipid-binding sites and the importance of negativ...
journal_title:Biochemistry
pub_type: 杂志文章
doi:10.1021/bi00094a030
更新日期:1993-11-02 00:00:00
abstract::The guanidine hydrochloride- (GuHCl-) induced unfolding and refolding of a recombinant domain of bovine microsomal cytochrome b(5) containing the first 104 amino acid residues has been characterized by both transient and equilibrium spectrophotometric methods. The soluble domain is reversibly unfolded and the equilibr...
journal_title:Biochemistry
pub_type: 杂志文章
doi:10.1021/bi991413j
更新日期:1999-10-26 00:00:00
abstract::We have studied the role of amphipathic alpha-helices in the ability of apoA-I to promote cholesterol efflux from human skin fibroblasts and activate lecithin:cholesterol acyltransferase (LCAT). Three apoA-I mutants were designed, each by deletion of a pair of predicted adjacent central alpha-helices [Delta(100-143), ...
journal_title:Biochemistry
pub_type: 杂志文章
doi:10.1021/bi981205b
更新日期:1998-09-29 00:00:00
abstract::The gene encoding enzyme IIA(glc) (EIIA) of the phosphoenolpyruvate:sugar phosphotransferase system of Mycoplasma capricolum was cloned into a regulated expression vector. The purified protein product of the overexpressed gene was characterized as an active phosphoacceptor from HPr with a higher pI than previously des...
journal_title:Biochemistry
pub_type: 杂志文章
doi:10.1021/bi963090m
更新日期:1997-06-10 00:00:00
abstract::Arginase is a binuclear manganese metalloenzyme that serves as a therapeutic target for the treatment of asthma, erectile dysfunction, and atherosclerosis. In order to better understand the molecular basis of inhibitor affinity, we have employed site-directed mutagenesis, enzyme kinetics, and X-ray crystallography to ...
journal_title:Biochemistry
pub_type: 杂志文章
doi:10.1021/bi801911v
更新日期:2009-01-13 00:00:00
abstract::Staphylococcus aureus is a leading cause of surgical site infections that results in increased hospital stays due to the development of chronic wounds. Little is known about factors involved in S. aureus' ability to prevent wounds from healing. We discovered a novel secreted protein produced by a surgical site isolate...
journal_title:Biochemistry
pub_type: 杂志文章
doi:10.1021/acs.biochem.5b00523
更新日期:2015-08-11 00:00:00
abstract::Ca2+-free crystals of sarcoplasmic reticulum Ca2+-ATPase have, up until now, been obtained in the presence of inhibitors such as thapsigargin (TG), bound to the transmembrane region of this protein. Here, we examined the consequences of such binding for the protein. We found that, after TG binding, an active site liga...
journal_title:Biochemistry
pub_type: 杂志文章
doi:10.1021/bi701855r
更新日期:2007-12-25 00:00:00
abstract::Mutations in the gene encoding human ATP:cobalamin adenosyltransferase (hATR) can result in the metabolic disorder known as methylmalonic aciduria (MMA). This enzyme catalyzes the final step in the conversion of cyanocobalamin (vitamin B12) to the essential human cofactor adenosylcobalamin. Here we present the 2.5 A c...
journal_title:Biochemistry
pub_type: 杂志文章
doi:10.1021/bi061396f
更新日期:2006-12-26 00:00:00
abstract::Immunological methods, in parellel with measurement of ATPase activity, have been used to characterize the reactions of antibodies specific for light chains with myosin and its water-soluble proteolytic subfragments, heavy meromyosin (HMM) and subfragment 1 (HMM S-1). Antiserum to the 5,5'-dithiobis(2-nitro-enzoic aci...
journal_title:Biochemistry
pub_type: 杂志文章
doi:10.1021/bi00692a008
更新日期:1975-10-21 00:00:00
abstract::BtuB is a bacterial outer-membrane protein that transports vitamin B(12). Spectroscopic studies using site-directed spin labeling (SDSL) indicate that the N-terminus of BtuB undergoes a dramatic structural change from a docked (folded) to an undocked (unfolded) configuration upon substrate binding. However, this drama...
journal_title:Biochemistry
pub_type: 杂志文章
doi:10.1021/bi035439t
更新日期:2003-11-18 00:00:00
abstract::The effect of the polyene antibiotic amphotericin B on the electron paramagnetic resonance spectra of lipid probes intercalated in model membranes was examined. When the antibiotic was added to the aqueous phase, no spectral effects occurred. However, when the antibiotic was incorporated during membrane preparation, c...
journal_title:Biochemistry
pub_type: 杂志文章
doi:10.1021/bi00523a010
更新日期:1981-09-29 00:00:00
abstract::The aminoacylation kinetics of 19 different variants of yeast tRNATyr with nucleotide substitutions in positions 33-35 were determined. Substitution of the conserved uridine-33 does not alter the rate of aminoacylation. However, substitution of the anticodon position 34 or position 35 reduces Km from 2- to 10-fold and...
journal_title:Biochemistry
pub_type: 杂志文章
doi:10.1021/bi00367a072
更新日期:1986-09-23 00:00:00
abstract::Recent studies showed that p34(SEI-1), also known as TRIP-Br1 or SEI-1, plays a dual role in the regulation of cell-cycle progression. It exhibits the transactivation activity and regulates a number of genes required for G1/S transition, while it also binds and activates cyclin-dependent kinase 4 (CDK4) independent of...
journal_title:Biochemistry
pub_type: 杂志文章
doi:10.1021/bi0504658
更新日期:2005-10-11 00:00:00
abstract::Urea-induced unfolding of Na,K-ATPase from pig kidney and from shark salt gland was studied by electron paramagnetic resonance (EPR) spectroscopy of a nitroxyl derivative of maleimide covalently attached to sulfhydryl groups which are essential for activity. Urea-induced structural changes lead to the inhibition of Na...
journal_title:Biochemistry
pub_type: 杂志文章
doi:10.1021/bi901124j
更新日期:2009-09-29 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::The properties of the homogeneous cutinase I, cutinase II, and the nonspecific esterase isolated from the extracellular fluid of cutin-grown Fusarium solani F. pisi (R.E. Purdy and P.E. Kolattukudy (1975), Biochemistry, preceding paper in this issue) were investigated. Using tritiated apple cutin as substrate, the two...
journal_title:Biochemistry
pub_type: 杂志文章
doi:10.1021/bi00684a007
更新日期:1975-07-01 00:00:00
abstract::RuvC is a well-characterized Holliday junction resolvase from E. coli. The presence of symmetry in its preferred recognition sequence leads to ambiguity in the position of the crossover point in the junction, because a symmetric junction can undergo branch migration. Symmetric immobile junctions are junctions that con...
journal_title:Biochemistry
pub_type: 杂志文章
doi:10.1021/bi020319r
更新日期:2002-09-10 00:00:00
abstract::Histone tails in nucleosomes play critical roles in regulation of many biological processes, including chromatin compaction, transcription, and DNA repair. Moreover, post-translational modifications, notably lysine acetylation, are crucial to these functions. While the tails have been intensively studied, how the stru...
journal_title:Biochemistry
pub_type: 杂志文章
doi:10.1021/acs.biochem.6b01208
更新日期:2017-04-11 00:00:00
abstract::The stereochemistry of proton transfer in the isomerization of [4 beta-2H]-5-androstene-3,17- dione (1d) to 4-androstene-3,17-dione (3) catalyzed by 3-oxo-delta 5-steroid isomerase (KSI) has been reinvestigated. In H2O, approximately 65% of the label is retained in the product (3); of this, one-third is at C-4 and two...
journal_title:Biochemistry
pub_type: 杂志文章
doi:10.1021/bi953025x
更新日期:1996-05-21 00:00:00
abstract::The spin equilibria of several derivatives of human methemoglobin were probed by resonance Raman scattering. The intensity of lines in the Raman spectrum gives a measure of the high-spin (S = 5/2) to low-spin (S = 1/2) ratio which agrees well with the spin equilibria determined from direct magnetic susceptibility meas...
journal_title:Biochemistry
pub_type: 杂志文章
doi:10.1021/bi00438a056
更新日期:1989-06-13 00:00:00
abstract::Many strains of Campylobacter jejuni display modified heptose residues in their capsular polysaccharides (CPS). The precursor heptose was previously shown to be GDP-d-glycero-α-d-manno-heptose, from which a variety of modifications of the sugar moiety have been observed. These modifications include the generation of 6...
journal_title:Biochemistry
pub_type: 杂志文章
doi:10.1021/acs.biochem.0c00096
更新日期:2020-04-07 00:00:00
abstract::"Charged-to alanine" scanning mutagenesis of the catalytic subunit of the Saccharomyces cerevisiae cAMP-dependent protein kinase (C1) identified three glutamate residues, E171, E214, and E274, that are involved in the recognition of a peptide substrate, kemptide (Leu1Arg2Arg3Ala4Ser5Leu6Gly7). These glutamate residues...
journal_title:Biochemistry
pub_type: 杂志文章
doi:10.1021/bi00236a001
更新日期:1991-06-04 00:00:00
abstract::Two thiol-activated endopeptidases with pH optima near pH 7.5 were isolated from the supernatant fraction of rabbit brain homogenates by DEAE-cellulose chromatography, gel filtration and isoelectrofocusing. Peptide bond hydrolysis was measured quantitatively by ion-exchange chromatography with an amino acid analyzer. ...
journal_title:Biochemistry
pub_type: 杂志文章
doi:10.1021/bi00654a026
更新日期:1976-05-04 00:00:00
abstract::Antimicrobial peptides (AMPs) are important components of the host innate immune system. Papiliocin is a 37-residue AMP purified from larvae of the swallowtail butterfly Papilio xuthus. Magainin 2 is a 23-residue AMP purified from the skin of the African clawed frog Xenopus laevis. We designed an 18-residue hybrid pep...
journal_title:Biochemistry
pub_type: 杂志文章
doi:10.1021/acs.biochem.5b00392
更新日期:2015-06-30 00:00:00