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)

Retinal ganglion cells in Chinese hamsters were morphologically classified into alpha, beta and gamma cells by the horseradish peroxidase labeling method. The alpha cells had large somatic and dendritic fields. The beta cells were small to medium in somatic size and had small dendritic field size. The gamma cells had small to medium somatic and large dendritic fields. Each cell type had either symmetrical or asymmetrical dendrites arising from the soma. The dendrites of alpha, beta and gamma cells extended into either the internal or external stratum of the inner plexiform layer.
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PMID:[A morphological classification of retinal ganglion cells in Chinese hamsters]. 174 72

Synthesis of Sp and Rp diastereomers of Ap4A alpha S has been characterized in two enzymatic systems, the lysyl-tRNA synthetase from Escherichia coli and the Ap4A alpha, beta-phosphorylase from Saccharomyces cerevisiae. The synthetase was able to use both (Sp)ATP alpha S and (Rp)ATP alpha S as acceptors of adenylate thus yielding corresponding monothioanalogues of Ap4A,(Sp) Ap4A alpha S and (Rp)Ap4A alpha S. No dithiophosphate analogue was formed. Relative synthetase velocities of the formation of Ap4A,(Sp) Ap4A alpha S and (Rp)Ap4A alpha S were 1:0.38:0.15, and the computed Km values for (Sp)ATP alpha S and (Rp)ATP alpha S were 0.48 and 1.34 mM, respectively. The yeast Ap4A phosphorylase synthesized (Sp)Ap4A alpha S and (Rp)Ap4A alpha S using adenosine 5'-phosphosulfate (APS) as source of adenylate. The adenylate was accepted by corresponding thioanalogues of ATP. In that system, relative velocities of Ap4A, (Sp)Ap4A alpha S and (Rp)Ap4A alpha S formation were 1:0.15:0.60. The two isomeric phosphorothioate analogues of Ap4A were tested as substrates for the following specific Ap4A-degrading enzymes: (asymmetrical) Ap4A hydrolase (EC 3.6.1.17) from yellow lupin (Lupinus luteus) seeds hydrolyzed each of the analogues to AMP and the corresponding isomer of ATP alpha S; (symmetrical) Ap4A hydrolase (EC 3.6.1.41) from E. coli produced ADP and the corresponding diastereomer of ADP alpha S; and Ap4A phosphorylase (EC 2.7.7.53) from S. cerevisiae cleaved the Rp isomer only at the unmodified end yielding ADP and (Rp)ATP alpha S whereas the Sp isomer was degraded non-specifically yielding a mixture of ADP, (Sp)ADP alpha S, ATP and (Sp)ATP alpha S. For all the Ap4A-degrading enzymes, the Rp isomer of Ap4A alpha S appeared to be a better substrate than its Sp counterpart; stereoselectivity of the three enzymes for the Ap4A alpha S diastereomers is 51, 6 and 2.5, respectively. Basic kinetic parameters of the degradation reactions are presented and structural requirements of the Ap4A-metabolizing enzymes with respect to the potential substrates modified at the Ap4A-P alpha are discussed.
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PMID:P alpha-chiral phosphorothioate analogues of bis(5'-adenosyl)tetraphosphate (Ap4A); their enzymatic synthesis and degradation. 217 26

Homogeneous diadenosine 5',5'''-P1,P4-tetraphosphate alpha, beta-phosphorylase (Ap4A-phosphorylase), the enzyme recently found in yeast (Guranowski, A., and Blanquet, S. (1985) J. Biol. Chem. 260, 3542-3547) catalyzes an exchange reaction between the beta-phosphate of nucleoside diphosphate (NDP) and orthophosphate from the medium (Pi). The common purine and pyrimidine ribonucleoside diphosphates as well as ADP analogs modified either in aglycone, sugar, or at the anhydride bond beta-position are substrates. The Km and rate values for the NDP-Pi exchange reaction were estimated at pH optima. These optima are 6.5 for UDP, 7.0 for ADP or CDP, and 8.0 for GDP. In the presence of 10 mM K2HPO4, 0.1 mM EDTA, and 100 mM Hepes/KOH (pH 7.0), the Km for ADP is 0.7 mM with a rate constant at saturating ADP of 96 s-1. The Km value for orthophosphate is 2 mM. In the NDP-Pi exchange reaction, phosphate can be substituted with arsenate and apparent arsenolysis of NDPs yields corresponding nucleoside monophosphates. The same pH optimum of 6.5 is found for arsenolysis of ADP, GDP, and CDP. Whereas the Ap4A phosphorylase sulfhydryl groups are essential for catalyzing the Ap4A phosphorolysis, the NDP-Pi exchange reactions, and the arsenolysis of NDPs, the divalent metal ions (Mg2+, Mn2+, Ca2+, Co2+, and Cd2+), which had been shown to be essential cofactors of the former reaction, are not required for the two latter ones. Used at concentrations which are optimum for Ap4A phosphorolysis, the cations (particularly Mg2+ and Cd2+) inhibit the NDP-Pi exchange and the arsenolysis of NDPs. Interestingly, the Ap4A phosphorylase exhibits higher specificity for adenosine 5'-phosphosulfate (APS) than for any other NDP tested. The V/Km ratio is almost 5-fold higher with APS than with ADP. However, in the presence of orthophosphate, the APS is irreversibly converted to ADP. Thus, the enzyme displays a property already attributed to ADP-sulfurylase (EC 2.7.7.5), (Grunberg-Manago, M., Del Campillo-Campbell, A., Dondon, L., and Michelson, A. M. (1966) Biochim. Biophys. Acta 123, 1-16; Nicholls, R. G. (1977) Biochem. J. 165, 149-155).
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PMID:Diadenosine 5',5'''-P1, P4-tetraphosphate alpha, beta-phosphorylase from yeast supports nucleoside diphosphate-phosphate exchange. 300 35

Plasma membrane insulin receptors, affinity labeled by covalent crosslinking to receptor-bound 125I-labeled insulin, are shown to appear as a heterogeneous population of three major disulfide-linked complexes (Mr 350,000, 320,000, and 290,000) upon electrophoresis in highly porous dodecyl sulfate/polyacrylamide gels in the absence of reductant. This pattern is consistent in all rat and human tissues that were analyzed. Upon reduction of disulfide bonds, each of these receptor structures is dissociated in two successive steps. Low concentrations of dithiothreitol promote a first step of disulfide bond reduction in which the Mr 350,000 species splits into a Mr 210,000 form and the Mr 290,000 species splits into a Mr 160,000 form. In contrast, both the Mr 210,000 and Mr 160,000 receptor fragments are generated from the native Mr 320,000 species upon partial reduction, indicating an asymmetrical structure. The second step of receptor reduction occurs upon treatment of the native disulfide-linked receptor complexes with high concentrations of dithiothreitol. Under these conditions, the Mr 350,000 receptor yields a Mr 125,000 subunit, denoted as alpha, and a Mr 90,000 subunit, denoted as beta, whereas the Mr 290,000 receptor dissociates into the alpha subunit and a Mr 49,000 subunit, denoted as beta 1. The Mr 320,000 receptor band is found to consist of alpha, beta, and beta 1 subunits upon complete reduction. The partially reduced Mr 210,000 receptor fragment is composed of the alpha subunit disulfide-linked to the beta subunit, whereas the Mr 160,000 species consists of the alpha subunit disulfide-linked to the beta 1 subunit. Thus, the stoichiometry of the three ubiquitous native insulin receptor structures of Mr 350,000, 320,000, and 290,000 are (alpha) 2 (beta) 2, (alpha) 2 (beta) (beta 1), and (alpha) 2 (beta 1) 2, respectively.
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PMID:Electrophoretic resolution of three major insulin receptor structures with unique subunit stoichiometries. 693 60

The present study analyzed EEG power and coherence in subjects with seasonal affective disorder (SAD) during depressive episodes and during light-induced and summer remission. Baseline EEG activity was recorded during the winter period before light treatment (31 SAD patients, 30 control subjects); after 10 days of 2-h morning light treatment (10 SAD subjects); and during the summer period (14 SAD subjects, 27 control subjects). EEG power and coherence were calculated for the delta, theta-1, theta-2, alpha, beta-1 and beta-2 frequency bands. Compared with control subjects, SAD subjects had lower than normal EEG power in most frequency bands; asymmetrical distribution of delta, theta-1, theta-2 and alpha activity in parietal and temporal regions due to increased EEG power over the left electrode sites; and beta activity in the lateral frontal region due to increased beta power over the right electrode site. The foci of decreased EEG coherence were mainly in the right and left frontal and the right posterior regions. Remitted SAD subjects showed normalization of inter-hemispheric asymmetry in lateral frontal areas; increases of delta, theta-2, and alpha activity compared with control values; theta-1 activity in excess of control values; and disappearance of the foci of decreased coherence in anterior areas of the left hemisphere.
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PMID:Seasonal affective disorder: spatial organization of EEG power and coherence in the depressive state and in light-induced and summer remission. 1175 15

Given that the nature of hemispheric dysfunction is different in heterogeneous disorders, in the present investigation EEG power mapping was applied to establish neurophysiological profiles that might potentially discriminate patients with seasonal affective disorder (SAD) among other affective disorders. The baseline resting EEG activity was recorded from 31 depressed SAD patients and 30 controls. Power in the delta, theta-1, theta-2, alpha, beta-1 and beta-2 frequency bands was extracted by Fourier transformation. Patients were found to have a lower delta (in central, parietal, occipital, temporal, posterior-temporal areas), theta-1 (in central and parietal), theta-2 (in anterior-frontal, parietal, occipital) and alpha activity (in anterior-frontal, midfrontal, central, parietal and occipital areas) than controls. SAD subjects showed, compared to controls, an asymmetrical distribution of delta, theta-1, theta-2 and alpha activity in parietal and temporal regions due to an increase of EEG power over the right electrode sites, and beta activity in the lateral frontal region due to an increase of beta power over the right electrode site. It is assumed that differential hemispheric contributions of EEG spectra may discriminate between the varieties of depression or different depressive states.
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PMID:EEG mapping in seasonal affective disorder. 1220 18

Raman spectroscopy was used to distinguish the differences in the molecular organization of the alpha, beta' and beta polymorphs, as well as the liquid state, of tristearin with focus placed on the C=O, C-H and C-C Raman-active stretching regions. The ester carbonyl stretching region permitted polymorphic discrimination due to significant differences in the number of modes, their relative frequencies and their full-widths at half-maximum. In the liquid state, the absence of obvious signatures in this region indicated that many local micro-environments likely exist about the ester carbonyl of molten tristearin. The ratio between the symmetrical and asymmetrical C-H stretching modes was linearly correlated with the enthalpy of fusion for each polymorph. The C-C stretching modes, which provided insight into the trans/gauche content, were polymorph independent, but changed significantly upon transition into the liquid state (p < 0.05). Overall, Raman spectroscopy allowed for the quick discrimination of tristearin polymorphs from a conformational and thermodynamic perspective.
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PMID:Characterization of the three major polymorphic forms and liquid state of tristearin by Raman spectroscopy. 1905 67