Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P50583 (asymmetrical)
 12,197 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The interaction of the nonionic detergent Triton X-100 with phospholipid bilayers of liposomes made of egg yolk phosphatidylcholine was studied through the behavior of several physical properties. The dielectric permittivity spectra between 30 kHz and 13 MHz, the viscosity, the density, and the d.c. conductivity (1 kHz) of aqueous liposomes suspensions at various mole ratios were measured at 22 degrees C. For detergent-to-phospholipid ratios lower than 3, a dielectric relaxation process of characteristic frequency of about 50 kHz was recorded. This process does not appear for the liposomes in water, and becomes smaller and smaller for detergent-to-phospholipid ratios higher than 3. The viscosity of these suspensions showed a biphasic behavior, being remarkably increased by the detergent for concentration ratios lower than 3. The measured d.c. conductivity of these samples showed no relation with this process, being slightly increased when the detergent content is increased. As a conclusion of these results a well defined concentration range appears where the phospholipid organization changes forming highly asymmetrical structures.
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PMID:Effect of Triton X-100 on the physical properties of liposomes. 379 May 61

The substrate specificity of diadenosine 5',5"'-P1,P4-tetraphosphate pyrophosphohydrolase from Physarum polycephalum for dinucleoside polyphosphates has been determined by high-performance liquid chromatography (HP-LC). Elution of a strong anion-exchange resin with a pH and ionic strength gradient of ammonium phosphate separates a series of monoadenosine and diadenosine polyphosphates. Most of the corresponding guanine nucleotides are also resolved on this HPLC system. One mole each of Ap4A and Gp4G is symmetrically hydrolyzed to 2 mol of ADP and GDP, respectively. Ap3A, Ap5A, Ap6A, and Ap4 are hydrolyzed, and in each case ADP is one of the products. Gp3G, Gp5G, Gp6G, and Gp4 are also substrates, and in each case GDP is one of the products. AMP, ADP, ATP, Ap2A, ADPR, GMP, GDP, GTP, NAD+, and NADP+ are not substrates. No hydrolysis of the cap dinucleotides m7Gp3Am and m7Gp3Cm was detected by HPLC. Diadenosine tetraphosphate pyrophosphohydrolase preparations were also assayed for adenylate kinase, nucleotide diphosphate kinase, NAD(P)+ pyrophosphohydrolase, phosphodiesterase, cyclic nucleotide phosphodiesterase, phosphatase, and ribonuclease activities. These enzymic activities were not detectable in diadenosine tetraphosphate pyrophosphohydrolase. The symmetrical hydrolysis of Ap4A and Gp4G is an unique catalytic property that distinguishes diadenosine tetraphosphate pyrophosphohydrolase from P. polycephalum from diadenosine tetraphosphate phosphohydrolases from other organisms.
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PMID:Diadenosine 5',5"'-P1,P4-tetraphosphate pyrophosphohydrolase from Physarum polycephalum. Substrate specificity. 629 57

We report what we believe to be the first known case of linear nevus sebaceus syndrome with infantile spasms followed by Lennox-Gastaut syndrome. The EEG revealed hemihypsarrhythmia and then asymmetrical slow spike-wave complexes. A pneumoencephalogram showed dilation and distortion of the lateral ventricle ipsilateral to the facial nevus on the left side. A computerized tomographic scan disclosed low density in the left parietotemporal region, a feature not reported previously. The findings indicated extensive lateralized cerebral lesions.
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PMID:Linear nevus sebaceus syndrome. Report of a case with Lennox-Gastaut syndrome following infantile spasms. 697 8

Dinitrophenylation of rabbit muscle and yeast glyceraldehyde-3-phosphate dehydrogenases modifies only SH groups. The rabbit muscle apoenzyme loses 75% of its original activity upon dinitrophenylation of two SH groups per tetramer whereas the yeast apoenzyme is totally inactivated under the same conditions. Dinitrophenylation of the active-site cysteine-149 of rabbit muscle and yeast holoenzymes results in an loss of activity corresponding to a 'half-of-the-sites' and a 'full-sites' reactivity, respectively. Determination of the sulphydryl content of the modified enzymes shows an unmasking of the cysteine residues of the dinitrophenylated rabbit muscle apoenzyme which is not observed for the yeast protein. However, conformational changes are revealed for both dinitrophenylated apoenzymes by differential absorption spectroscopy or by limited proteolysis. Sulphydryl group unmasking is not observed after modification of the cysteine residues of the rabbit muscle holoenzyme but it does occur when dinitrophenylation is performed in the presence of two moles NAD+/mole rabbit muscle enzyme. Although the apoenzyme is sensitive to an induced conformational change, our results favour symmetrical structures for both yeast apo and holo enzymes. The bis-dinitrophenylated rabbit muscle apoenzyme presents all the characteristics of an asymmetrical structure; however, it is not possible to deduce whether this symmetry is due to the chemical modification or whether it preexists in the native apoenzyme. The results of the dinitrophenylation of the rabbit holoenzyme, however, indicate that this enzyme possesses an asymmetrical structure.
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PMID:Structure and reactivity relationship in glyceraldehyde-3-phosphate dehydrogenase. Dinitrophenylation of cysteine residues of yeast and rabbit muscle enzymes. 703 Jul 43

Low concentrations of methanol, 2-propanol and ethylene glycol increase the asymmetry of the flagellar waveforms ad the turning rate of both live sperm and potentially symmetrical sperm reactivated with 1 mM-MgATP2-, while at the same time causing a decrease in the heat frequency. Similar effects are observed if the solvents are added to preparations of potentially symmetrical sperm reactivated in the presence of 1 mM free Ca2+, or to potentially asymmetrical sperm reactivated without added Ca2+, A second group of solvents, N,N-dimethylformamide, formamide and p-dioxane, also decrease the flagellar beat frequency, but have the opposite effect on symmetry, reducing the asymmetry of the waveforms and the turning rate of potentially symmetrical sperm reactivated in the presence of 1 mM free Ca2+. These effects of solvents are all reversible within about 5 min after initial exposure to solvent. Higher concentrations of methanol and 2-propanol (above approximately 5 and 0.8 mole %, respectively) induce quiescence in potentially asymmetrical sperm reactivated with concentrations of MgATP2- ranging from 10 microM to 1 mM. The quiescent flagella initially assume a bent form very similar to that seen in Ca2+-induced quiescence, and show a subsequent time-dependent distortion of the initial bent from with eventual disintegration and splitting off of bundles of microtubules. Dimethylformamide, formamide and dioxane have almost no effect on the intrinsic asymmetry of potentially asymmetrical sperm reactivated in the absence of added Ca2+, but addition of these solvents to potentially asymmetrical sperm that have been induced to become quiescent by addition of 0.1 mM free Ca2+ causes the sperm to resume swimming with flagellar waveforms that are substantially more symmetrical that those of the starting preparation before the addition of Ca2+. Mild digestion with trypsin of reactivated sperm that have been induced either to beat asymmetrically or to become quiescent by addition of methanol causes a gradual appearance of symmetrical flagellar beating, as in the case of Ca2+-induced quiescence. The flagellar beat frequency, however, remains low, at about 20 Hz. The results suggest that the solvents either mimic or block the action of CA2+ by interaction with a Ca2+-dependent regulatory protein, and may also induce alteration in the rate constants of dynein ATPase.
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PMID:Effects of organic solvents on flagellar asymmetry and quiescence in sea urchin sperm. 707 22

Mole rats were videotaped while locomoting in a Plexiglas tube to evaluate the effects of inclination on locomotion. Animals moving uphill preferred to go backward using plantigrade foot postures, presumably to prevent sliding. Uphill backward locomotion also allowed animals to cope with changes in weight distribution between the hind and forelimbs without modifying footfall pattern relative to the direction of progression. When the animals did use uphill forward strides, they switched to asymmetrical gaits, which are associated with increased propulsive forces. These and prior results suggest that weight distribution and direction of progression can modify the natural pattern of stepping in mammalian quadrupeds.
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PMID:Uphill locomotion in mole rats: a possible advantage of backward locomotion. 858 56

1. The delayed rectifier (DR) K+ channel pore was probed using different permeant and blocking ions applied intra- and extracellularly. Currents were recorded from bullfrog sympathetic neurons using whole-cell patch-clamp techniques. 2. With intra- and extracellular Cs+ (0 K+), there were large, tetraethylammonium (TEA)-sensitive currents. Adding K+ back to the extracellular solution revealed that the current with Cs+i was K+ selective (permeability ratio PCs/PK = 0.17 +/- 0.02, n = 4) and showed a strong anomalous mole fraction effect. 3. There were also large non-inactivating currents with Na+i and Na+o (0 K+). The current with Na+i was K+ selective (Na+o vs. K+o: PNa/PK = 0.022 +/- 0.005, n = 5), and was TEA sensitive with K+o but not with Na+o. 4. Permeant ions affected gating kinetics. DR currents activated faster in K+ than in Cs+, and activated faster with increasing concentrations of either K+ or Cs+. Deactivation was slowed by increased K+ or Cs+ concentration, with no difference between K+ and Cs+. 5. The pore was also characterized using intracellular blocking ions. A wide variety of monovalent cations (TEA, N-methyl-D-glucamine, arginine, choline, CH3NH3+, Li+, Cs+ and Na+) blocked DR channels from the inside in a voltage-dependent manner: KD at 0 mV was 2.9 mM for TEA and 134-487 mM for the others, at apparent electrical distances (delta) of 0.33-0.79. There was no detectable block by 10 mM Mgi2+. Apart from TEA, the organic cations did not block from the outside. 6. The permeability to Na+ in the absence of K+, and the strong anomalous mole fraction effects observed for Cs+o + K+o mixtures, suggest that DR channels select for K+ using ion-ion competition. The block by large intracellular cations shows that the pore is asymmetrical. The loss of high affinity TEAo block with Na+i and Na+o, and the effects of permeant ions on gating, suggest that channel conformation may be affected by ions in the pore.
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PMID:Delayed rectifier current of bullfrog sympathetic neurons: ion-ion competition, asymmetrical block and effects of ions on gating. 908 Mar 70

Halo reactions to melanocytic nevi are a well-recognized phenomenon. In contrast, halo reactions to Spitz's nevi have been reported only infrequently. Halo reactions may cause misdiagnosis of an otherwise benign nevus as melanoma because inflammatory cells sometimes obscure the architectural features of the underlying nevus, and may induce cytologic atypia. For Spitz's nevus where the distinction between malignancy and benignancy is already challenging, halo reactions compound the problem. We describe 17 examples of Spitz's nevus with halo reaction, and compare their immunohistochemical features with those of "ordinary" halo nevi. Only 2 of 17 lesions demonstrated clinically apparent halos. Clinical follow-up was available for 12 of 17 cases. None of the 12 has persisted at the biopsy site or metastasized after an average 3.6-year follow-up period. Junctional, compound, intradermal, and combined types of Spitz's nevi were represented. All were characterized by symmetrical lymphocytic infiltrates which permeated the full thickness of the nevus, including junctional nests. Combined Spitz's nevi constituted more than one-half of examples in this series (9/17 cases). The combined Spitz's nevus included a combination of Spitz's nevus with either an ordinary (common, banal) nevus or a superficial congenital type nevus. In these combined Spitz's nevi, the lymphocytic response was often directed exclusively to the Spitz's nevic component. Important distinguishing features from malignant melanoma arising in a pre-existing nevus included symmetry and lateral circumscription of the spitzoid component, no large expansile-appearing aggregates of melanocytes, a decrease in size of nests with increasing dermal depth, a lack of mitotic figures among melanocytes at the base, and a symmetrical and diffusely permeative lymphocytic response. Although the combined Spitz's nevus with halo reaction sometimes appeared asymmetrical at scanning magnification, each component of the combination was symmetrical, when examined independently. Probably because of reactive atypia, nuclear maturation with progressive descent into the dermis was sometimes absent. There were no obvious differences in immunohistochemical staining patterns among 4 Spitz's nevi with halo reaction, 5 regressing melanomas, and 5 benign halo nevi when stained with antibodies to S100, HMB-45, OPD4, CD8, TIA-1, CD1a, CD68, and Ki-67.
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PMID:Spitz's nevi with halo reaction: a histopathologic study of 17 cases. 944 88

A family of sequence-related 2'-aminopyrimidine, 2'-hydroxylpurine aptamers, developed by oligonucleotide-based combinatorial chemistry, SELEX (systematic evolution of ligand by exponential enrichment) technology, binds human nonpancreatic secretory phospholipase A2 (hnps-PLA2) with nanomolar affinities and inhibits enzymatic activity. Aptamer 15, derived from the family, binds hnps-PLA2 with a Kd equal to 1.7 +/- 0.2 nM and, in a standard chromogenic assay of enzymatic activity, inhibits hnps-PLA2 with an IC50 of 4 nM, at a mole fraction of substrate concentration of 4 x 10(-6) and a calculated Ki of 0.14 nM. Aptamer 15 is selective for hnps-PLA2, having a 25- and 2500-fold lower affinity, respectively, for the unrelated proteins human neutrophil elastase and human IgG. Contractions of guinea pig lung pleural strips induced by hnps-PLA2 are abolished by 0.3 microM aptamer 15, whereas contractions induced by arachidonic acid are not altered. The structure that is essential for binding and inhibition appears to be a 40-base hairpin/loop motif with an asymmetrical internal loop. The affinity and activity of the aptamers demonstrate the ability of the SELEX process to isolate antagonists of nonnucleic-acid-binding proteins from vast oligonucleotide combinatorial libraries.
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PMID:High-affinity aptamers selectively inhibit human nonpancreatic secretory phospholipase A2 (hnps-PLA2). 952 54

Can we use rate constants and state models to describe ion transport through gramicidin channels? Maybe, but only if rate constants are just proportionality constants between rates and probabilities of observing states of the channel. This approach is natural if the system of channel plus ions (plus water) is almost always in one or another of a small number of identifiable states. Many features of ion transport through gramicidin, including the conductance-concentration relationship, concentration-dependent permeability ratios, anomalous mole fraction effect and to some extent flux ratio exponents, are consistent with a description in which there are four occupation 'states' of the pore: only water; an ion at one end; an ion at the other; and ions at both ends. Current-voltage relationships can (and must) also be fitted, but until there is a theory to predict the potential dependence of the rate constants this success will remain hollow. Other features have resisted interpretation. These include the failures to determine 'binding constants' consistent with all the data; the variation of flux ratio exponents with ion type; and, probably, the variation of the currents with asymmetrical ion concentrations. Nevertheless, state models still have one attractive feature, they allow consideration of the effects that one ion within the pore has on the movements of another.
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PMID:Can we use rate constants and state models to describe ion transport through gramicidin channels? 1047 50


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