Abstract:
:The circular dichroism of hypothetical, water-filled, spherical shells, 75-3500 nm in radius, with walls 7.5 nm thick, composed of poly(L-lysine) in various conformational proportions, and suspended in water, were computed from the known optical properties of this polypeptide by classical general light-scattering theory (Mie theory). Comparison of the computed curves of circular dichroism spectra with those of diverse membranes reveals large discrepancies below 215 nm and shows that light scattering does not adequately account for the optical activity of membranes containing appreciable proportions of nonhelical conformation. However, turbidity effects can explain the anomalies of membrane optical rotatory dispersion near 233 nm, if not uniquely so. We conclude that the optical activity of neither most soluble proteins nor membrane proteins can provide accurate conformational information when synthetic polypeptides are used as standards and list the reasons for this argument. We also show that present techniques to "correct" membrane optical activity are likely to produce additional artifact.
journal_name
Proc Natl Acad Sci U S Aauthors
Wallach DF,Low DA,Bertland AVdoi
10.1073/pnas.70.11.3235subject
Has Abstractpub_date
1973-11-01 00:00:00pages
3235-9issue
11eissn
0027-8424issn
1091-6490journal_volume
70pub_type
杂志文章abstract::Some tumor cell lines secrete high concentrations of TGFbeta or IL-1. Similarly high concentrations of each of these cytokines cross-activate the other pathway: TGFbeta activates NFkappaB, and IL-1beta activates Smads. The IL-1 signaling components IRAK, MyD88, TRAF6, and TAK1 are all required for cross-activation of ...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0700118104
更新日期:2007-03-13 00:00:00
abstract::Iron-sulfur clusters function as cofactors of a wide range of proteins, with diverse molecular roles in both prokaryotic and eukaryotic cells. Dedicated machineries assemble the clusters and deliver them to the final acceptor molecules in a tightly regulated process. In the prototypical Gram-negative bacterium Escheri...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1322728111
更新日期:2014-06-03 00:00:00
abstract::Nannofossils section sign here described are from the middle Proterozoic Paradise Creek Formation, along Paradise Creek in northwestern Queensland, Australia. These fossils, in chert blebs associated with branched stromatolites, comprise cubic colonies analogous to living Eucapsis, a member of the blue-green algal fam...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.62.1.56
更新日期:1969-01-01 00:00:00
abstract::Reduced intake of nutrients [calorie restriction (CR)] extends longevity in organisms ranging from yeast to mammals. Mutations affecting somatotropic, insulin, or homologous signaling pathways can increase life span in worms, flies, and mice, and there is considerable evidence that reduced secretion of insulin-like gr...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0600161103
更新日期:2006-05-16 00:00:00
abstract::Critical to the maintenance of circadian rhythmicity is the cyclic expression of at least some components of the central oscillator. High-amplitude cycling of mRNA and protein abundance, protein phosphorylation and nuclear/cytoplasmic shuttling have all been implicated in the maintenance of circadian period. Here we u...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0736949100
更新日期:2003-04-15 00:00:00
abstract::The assembly of tiny magnetic particles in external magnetic fields is important for many applications ranging from data storage to medical technologies. The development of ever smaller magnetic structures is restricted by a size limit, where the particles are just barely magnetic. For such particles we report the dis...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1511443112
更新日期:2015-11-24 00:00:00
abstract::We tested a theoretical prediction that patterns of excitatory input activity that consistently fail to activate target neurons sufficiently to induce synaptic potentiation will instead cause a specific synaptic depression. To realize this situation experimentally, the Schaffer collateral projection to area CA1 in rat...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.89.10.4363
更新日期:1992-05-15 00:00:00
abstract::An examination of life expectancy in 1963 reveals twin peaks in the empirical distribution across countries: one group of countries clustered around a life expectancy of 40 years and a second group clustered around a life expectancy of 65 years. By 2003, the mode of each cluster had moved up by approximately 10 years....
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0702012104
更新日期:2007-10-09 00:00:00
abstract::Numbers of substitutions per site for 15 protein-coding genes and six introns of the plant mitochondria were estimated to compare modes and tempos of evolution between exons and introns, and numbers of insertions-deletions per site also were investigated in introns. Intra-gene homogeneity of numbers of substitutions p...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.94.11.5722
更新日期:1997-05-27 00:00:00
abstract::Neither the structure nor the function of alpha-bungarotoxin (alpha Bgtx) binding molecules in the nervous system have yet been completely defined, although it is known that some of these molecules are related to cation channels and some are not. Using an improved method of affinity chromatography, we have isolated a ...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.88.8.3258
更新日期:1991-04-15 00:00:00
abstract::In skeletal muscle, dihydropyridine receptors and dihydropyridine-sensitive Ca2+ channels are preferentially localized in the transverse tubular membranes. Starting with an antigenic membrane fraction enriched in rabbit muscle transverse tubules (T-tubules), several monoclonal antibodies were produced by a fusion of s...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.84.14.5019
更新日期:1987-07-01 00:00:00
abstract::Mitochondrial cytochrome c oxidase plays an essential role in aerobic cellular respiration, reducing dioxygen to water in a process coupled with the pumping of protons across the mitochondrial inner membrane. An aspartate residue, Asp-51, located near the enzyme surface, undergoes a redox-coupled x-ray structural chan...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.2635097100
更新日期:2003-12-23 00:00:00
abstract::Transplantation of pancreatic islets for treating type 1 diabetes is restricted to patients with critical metabolic lability resulting from the need for immunosuppression and the shortage of donor organs. To overcome these barriers, we developed a strategy to macroencapsulate islets from different sources that allow t...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1708420114
更新日期:2017-10-31 00:00:00
abstract::We studied the abundance and structure of globin mRNAs present in K562 cells both before and after induction of hemoglobin synthesis by hemin. In vitro translation of poly(A)+ RNA from K562 cells generated protein products corresponding to alpha, A gamma-, G gamma-, epsilon-, and zeta-globin mRNAs. Individual globin m...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.80.18.5515
更新日期:1983-09-01 00:00:00
abstract::The probability of choosing an alternative in a long sequence of repeated choices is proportional to the total reward derived from that alternative, a phenomenon known as Herrnstein's matching law. This behavior is remarkably conserved across species and experimental conditions, but its underlying neural mechanisms st...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0505220103
更新日期:2006-10-10 00:00:00
abstract::Corticotropin (ACTH) and melanotropin (MSH) peptides (melanocortins) are produced not only in the pituitary but also in the brain, with highest concentrations in the arcuate nucleus of the hypothalamus and the commisural nucleus of the solitary tract. We have identified a receptor for MSH and ACTH peptides that is spe...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.90.19.8856
更新日期:1993-10-01 00:00:00
abstract::TGF-β activated kinase 1 (TAK1) is a critical signaling hub responsible for translating antigen binding signals to immune receptors for the activation of the AP-1 and NF-κB master transcriptional programs. Despite its importance, known substrates of TAK1 are limited to kinases of the MAPK and IKK families and include ...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1608355113
更新日期:2016-08-16 00:00:00
abstract::The minimal size of the recombination site required for efficient FLP recombinase-catalyzed recombination in vitro is no more than 28 base pairs, which includes parts of two 13-base-pair inverted repeats and all of an 8-base-pair spacer. The FLP recombinase cleaves the DNA at the boundaries of the spacer, becomes cova...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.82.21.7270
更新日期:1985-11-01 00:00:00
abstract::Neuronal dynamics display a complex spatiotemporal structure involving the precise, context-dependent coordination of activation patterns across a large number of spatially distributed regions. Functional magnetic resonance imaging (fMRI) has played a central role in demonstrating the nontrivial spatial and topologica...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 临床试验,杂志文章
doi:10.1073/pnas.1400181111
更新日期:2014-07-15 00:00:00
abstract::Chronic, relapsing myelitis has been induced in golden Syrian hamsters by the intracerebral inoculation of measles virus when the animals were less than 1 day old. No acute illness was seen in animals that developed myelitis, and the onset of the myelitis was at 5 to 50 weeks after infection. In most animals the illne...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.77.7.4297
更新日期:1980-07-01 00:00:00
abstract::C.B-17 severe combined immunodeficient (scid) mice carry the scid mutation and are severely deficient in both T cell- and B cell-mediated immunity, apparently as a result of defective V(D)J joining of the immunoglobulin and T-cell receptor gene elements. In the present studies, we have defined the tissue, cellular, an...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.88.4.1394
更新日期:1991-02-15 00:00:00
abstract::Recently, surface-sensitive spectroscopy data and molecular dynamics simulations have generated intense interest in the distribution of electrolyte ions between bulk water and the air/water interface. A partitioning model for cations and anions developed for biopolymer surface is extended here to interpret the effects...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0606256103
更新日期:2006-09-26 00:00:00
abstract::Two 1,4-benzoquinone derivatives, found in the venom of the scorpion Diplocentrus melici following exposure to air, have been isolated, characterized, synthesized, and assessed for antimicrobial activities. Initially a white, viscous liquid, the extracted venom colors within minutes under ambient conditions. From this...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1812334116
更新日期:2019-06-25 00:00:00
abstract::In binocular rivalry, a subject views two incongruent stimuli through each eye but consciously perceives only one stimulus at a time, with a switch in perceptual dominance every few seconds. To investigate the neural correlates of perceptual dominance in humans, seven subjects were recorded with a 148-channel magnetoe...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.95.6.3198
更新日期:1998-03-17 00:00:00
abstract::Social networks exhibit strikingly systematic patterns across a wide range of human contexts. Although genetic variation accounts for a significant portion of the variation in many complex social behaviors, the heritability of egocentric social network attributes is unknown. Here, we show that 3 of these attributes (i...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0806746106
更新日期:2009-02-10 00:00:00
abstract::We construct a C*-algebra that has only one irreducible representation up to unitary equivalence but is not isomorphic to the algebra of compact operators on any Hilbert space. This answers an old question of Naimark. Our construction uses a combinatorial statement called the diamond principle, which is known to be co...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0401489101
更新日期:2004-05-18 00:00:00
abstract::The nonlinear nature of integration among cortical brain areas renders the effective connectivity between them inherently dynamic and context-sensitive. One emerging architectural principle of functional brain organization, which rests explicitly on these nonlinear interactions, is that neuronal responses expressed at...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.97.13.7591
更新日期:2000-06-20 00:00:00
abstract::Silicon, with its great abundance and mature infrastructure, is a foundational material for a range of applications, such as electronics, sensors, solar cells, batteries, and thermoelectrics. These applications rely on the purification of Si to different levels. Recently, it has been shown that nanosized silicon can o...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1513012112
更新日期:2015-11-03 00:00:00
abstract::Gene therapy of the brain is hindered by the presence of the blood-brain barrier (BBB), which prevents the brain uptake of bloodborne gene formulations. Exogenous genes have been expressed in the brain after invasive routes of administration, such as craniotomy or intracarotid arterial infusion of noxious agents causi...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.130187497
更新日期:2000-06-20 00:00:00
abstract::Proteins with intrinsically disordered domains are implicated in a vast range of biological processes, especially in cell signaling and regulation. Having solved the quaternary structure of the folded domains in the tumor suppressor p53 by a multidisciplinary approach, we have now determined the average ensemble struc...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0801353105
更新日期:2008-04-15 00:00:00