Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0027960 (mole)
 21,279 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The initial step in the purification of Dictyostelium myosin II heavy chain kinase A (MHCK A) is chromatography over phosphocellulose. Fractions containing MHCK A are pooled and chromatographed over a Mono Q column (Pharmacia LKB Biotechnology) equilibrated in 0.15 M KCl. Under these conditions MHCK A and most of the contaminating proteins elute in the flowthrough. The addition of Mg2+ and ATP to the Mono Q flowthrough results in the phosphorylation, within 15 min, of MHCK A to a level of 10 mol of phosphate per mole of 130-kDa kinase subunit. The hyperphosphorylated MHCK A binds to Mono Q columns in the presence of 0.15 M KCl and can be eluted, as a single homogeneous band, by a salt gradient to 0.35 M KCl. A similar purification procedure may prove useful for other proteins which can be highly phosphorylated. Hyperphosphorylation is shown to have no effect on the position at which MHCK A elutes from gel filtration columns (apparent M(r) greater than 700,000).
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PMID:Purification of Dictyostelium myosin II heavy chain kinase A based on the increase in negative charge accompanying hyperphosphorylation. 196 23

Superoxide dismutase was isolated from each of the anaerobically grown organisms Actinomyces naeslundii, Actinomyces strain E1S.25D, and Actinomyces odontolyticus. The enzymes were 100,000-110,000 mol wt acidic proteins (pI 4.3-4.6) and contained Mn and Zn, but no detectable Fe. The Mn and Zn content varied with the enzyme source. A. naeslundii superoxide dismutase, specific activity 2200 U/mg, contained 2.3 g atoms Mn and 1.4 g atoms Zn per mole tetramer whereas A. odontolyticus SOD, specific activity 700 U/mg, contained 1.4 g atoms Mn and 1.8 g atoms Zn per mole tetramer. Actinomyces strain E1S.25D, specific activity 1300 U/mg, contained 1.8 g atoms Mn and 1.2 g atoms Zn per mole tetramer. The amino acid compositions of the enzymes were comparable except for arginine, lysine, and tryptophan content. The enzymatic activity of each enzyme was stable in 5 mM H2O2 at 23 degrees C for 2 h. The enzymes were only modestly inhibited by 20 mM NaN3. The enzymatic activity was increased at low ionic strength but was markedly decreased at increased ionic strength with each salt tested except sodium perchlorate, which caused marked inhibition even at low ionic strength. Polyclonal antibodies to A. naeslundii and Actinomyces strain E1S.25D precipitated and inactivated their respective antigens whereas the precipitated A. odontolyticus superoxide dismutase-antibody complex retained virtually full catalytic activity. Immunological studies revealed that the native A. naeslundii and Actinomyces strain E1S.25D MnSODs share common epitopes and cross-reacted with precipitin lines of complete identity in Ouchterlony double diffusion gels. Antibody to the A. odontolyticus enzyme displayed only partial cross-reactivity with superoxide dismutase from the two other Actinomyces. Western blotting of the denatured antigens revealed reactivities of the antibodies that differed only slightly from the results of the Ouchterlony gels.
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PMID:Tetrameric manganese superoxide dismutases from anaerobic Actinomyces. 211 98

Circular Dichroism (CD) spectra were collected as a function of sodium perchlorate concentration [NaClO4] for the set of DNA hairpins formed from the oligomer sequences d[(CG)3X4(CG)3] where X = A, T, G or C. Over the range in salt concentration from 0 to 4.0 M NaClO4, the CD spectra invert in a manner characteristic of the B to Z transition. A factor analysis routine is described and employed to determine the least number of basis spectra required to fit the measured spectra of each hairpin over the entire salt range examined. In every case, linear combinations of only two sub-spectra fit the experimental spectra of the hairpins with greater than 98% accuracy, indicating the spectrally monitored structural transitions are two-state. From the relative weights of the individual sub-spectra, B-Z transition curves are constructed. The transitions are analyzed in terms of a simple two-state equilibrium model which yields an evaluation of the transition free-energy, delta GB-Z, as a function of NaClO4 concentration. At 1.0 M NaClO4 and 21 degrees C, delta GB-Z = 5.4, 4.9, 3.6 and 2.3 kcal/mole for the G4, T4, A4 and C4 loop hairpins, respectively.
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PMID:B to Z transitions of the short DNA hairpins formed from the oligomer sequences: d[(CG)3X4(CG)3] (X = A, T, G, C). 230 46

Patch-clamp recording from the apical surface of the epithelium of frog lens reveals a cation-selective channel after pressure (about +/- 30 mm Hg) is applied to the pipette. The open state of this channel has a conductance of some 50 pS near the resting potential (-56.1 +/- 2.3 mV) when 107 mM NaCl and 10 HEPES (pH 7.3) is outside the channel. The probability of the channel being open depends strongly on pressure but the current-voltage relation of the open state does not. With minimal Ca2+ (55 +/- 2 microM) outside the channel, the current-voltage relation is nonlinear even in symmetrical salt solutions, allowing more current to flow into the cell than out. The channel, in minimal Ca2+ solution, is selective among the monovalent cations in the following sequence K+ greater than Rb+ greater than Cs+ greater than Na+ greater than Li+. The conductance depends monotonically on the mole fraction of K+ when the other ion present is Li+ or Na+. The single-channel current is a saturating function of [K+] when K+ is the permeant ion, for [K+] less than or equal to 214 mM. When [Ca2+] = 2 mM, the current-voltage relation is linearized and the channel cannot distinguish Na+ and K+.
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PMID:A cation channel in frog lens epithelia responsive to pressure and calcium. 243 53

Batrachotoxin-modified, voltage-dependent sodium channels from canine forebrain were incorporated into planar lipid bilayers. Single-channel conductances were studied for [Na+] ranging between 0.02 and 3.5 M. Typically, the single-channel currents exhibited a simple two-state behavior, with transitions between closed and fully open states. Two other conductance states were observed: a subconductance state, usually seen at [NaCl] greater than or equal to 0.5 M, and a flickery state, usually seen at [NaCl] less than or equal to 0.5 M. The flickery state became more frequent as [NaCl] was decreased below 0.5 M. The K+/Na+ permeability ratio was approximately 0.16 in 0.5 and 2.5 M salt, independent of the Na+ mole fraction, which indicates that there are no interactions among permeant ions in the channels. Impermeant and permeant blocking ions (tetraethylammonium, Ca++, Zn++, and K+) have different effects when added to the extracellular and intracellular solutions, which indicates that the channel is asymmetrical and has at least two cation-binding sites. The conductance vs. [Na+] relation saturated at high concentrations, but could not be described by a Langmuir isotherm, as the conductance at low [NaCl] is higher than predicted from the data at [NaCl] greater than or equal to 1.0 M. At low [NaCl] (less than or equal to 0.1 M), increasing the ionic strength by additions of impermeant monovalent and divalent cations reduced the conductance, as if the magnitude of negative electrostatic potentials at the channel entrances were reduced. The conductances were comparable for channels in bilayers that carry a net negative charge and bilayers that carry no net charge. Together, these results lead to the conclusion that negative charges on the channel protein near the channel entrances increase the conductance, while lipid surface charges are less important.
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PMID:Batrachotoxin-modified sodium channels in planar lipid bilayers. Ion permeation and block. 244 Sep 77

The reactive thiol of the myosin head, SH-1, can be selectively labelled in glycerinated rabbit muscle fibres. This residue has been used as an attachment site for either fluorescent or spectroscopic probes which report on head movements and orientations in various functional states of muscle. We have specifically modified SH-1 in vitro, using purified rabbit myosin and conditions similar to those employed in the labelling of muscle fibres (low ionic strength [40 mM NaCl] at 4 degrees C), with stoichiometric amounts of either [14C]-iodoacetamide, 5-(2[iodoacetyl)amino)ethyl) aminonaphthalene-1- sulphonic acid (IAEDANS), or 4-(2-iodoacetamido-2,2,6,6-tetramethyl piperidinooxyl (IASL). The specificity of modification was determined by measuring the well-defined alterations in the high salt ATPase activities of myosin and by localizing both IAAm and IAEDANS to the 20-kDa C-terminal subfragment 1 (S1) which contains SH-1. The low ionic strength actin-activated Mg2+-ATPase of SH-1-modified rabbit myosin was measured in the presence of the thin filament regulatory, complex, troponin-tropomyosin. A significant increase in this activity in the absence of calcium, concomitant with a decrease in activity in the presence of calcium, was observed as the extent of SH-1 modification was incrementally increased from zero to one mole of label bound per mole of SH-1. The elevated myosin Mg2+-ATPase, which results from SH-1 modification, does not account for the increased actin-activated Mg2+-ATPase in resting conditions (i.e. in the absence of calcium).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:SH-1 modification of rabbit myosin interferes with calcium regulation. 252 9

Thermodynamic properties of bilayer assembly have been obtained from measurements of the solubility of the sodium salt of dimyristoylphosphatidylglycerol (DMPG) in water. The standard free energy of bilayer assembly delta G degree a is shown to be RT 1n Xs + zF psi 0 where Xs is the mole fraction of dissolved lipid, F is the Faraday constant, z is the valence of the counterion (Na+), and psi 0 is the electrical double-layer potential of the ionized bilayer. The function d 1n Xs/dT was found to be discontinuous at 24 degrees C, the gel-liquid-crystal transition temperature (Tm) for DMPG. This function was unaffected when solubilities were measured in 0.001 M NaCl solutions; thus, psi 0 is constant in the experimental temperature interval (4-40 degrees C). Using a value of psi 0 = -180 mV [Eisenberg et al. (1979) Biochemistry 18, 5213-5223], and the temperature dependence of delta G degrees a, values for delta H degrees a and delta S degree a at 24 degrees C were calculated for the gel and liquid-crystal states of DMPG. For the gel, delta H degrees a and T delta S a are -26.2 and 12.7 kcal/mol, respectively; for the liquid-crystal, delta H degrees a and T delta S degrees a are -19.2 and -5.7 kcal/mol, respectively. The calculated value for the latent heat of the gel-liquid-crystal transition is 7 kcal/mol, in agreement with calorimetric measurements.
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PMID:Thermodynamics of phospholipid bilayer assembly. 276 83

2-Sulfobenzoic cyclic anhydride (SBA) rapidly and selectively inactivates porcine pancreatic lipase (PPL) only when added during the hydrolysis of an emulsified ester such as tributyrin or dodecyl acetate. The present data suggest that the inactivation of PPL occurs preferentially at the oil/water interface and not in the aqueous phase, since colipase and bile salt were found to adversely affect the inhibition process. Moreover, it is shown that at a molar ratio of SBA to pure PPL of 1, 40% of the lipase activity was already irreversibly lost. Complete inactivation was observed at SBA to pure PPL molar ratios of 120. A 60% inactivation occurred when 0.5 mol of 3H-labeled SBA was attached per mole of PPL. The SBA-inactivated PPL competes for binding to the dodecyl acetate/water interface as efficiently as the native enzyme. Larger SBA concentrations are required when crude lipase preparations are used as well as with pure PPL in the presence of bile salts and colipase. Lipases were found to have variable sensitivities to SBA inactivation, depending on their origin. In the presence of bile salts and tributyrin at pH 6.0, human gastric lipase activity was not affected by the presence of a 10(6) molar excess of SBA.
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PMID:Interface-mediated inactivation of pancreatic lipase by a water-reactive compound: 2-sulfobenzoic cyclic anhydride. 279 2

Occlusion of Rb+ by C12E8-solubilized (Na+ + K+)-ATPase from shark salt glands has been measured. The rate of de-occlusion at room temperature is about 1 s-1, which is the same as for the membrane-bound enzyme. The amount of Rb+ occluded is 3 moles Rb+ per mole membrane-bound shark enzyme, whereas only about 2 moles Rb+ are occluded by the C12E8-solubilized enzyme.
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PMID:Occlusion of Rb+ by detergent-solubilized (Na+ + K+)-ATPase from shark salt glands. 298 93

Mixtures of the dissimilatory nitrite reductase cytochrome cd1 from Pseudomonas aeruginosa and potential electron-donating proteins were prepared in both fully oxidized and fully reduced states and examined by 1H NMR spectroscopy. The relatively narrower lines of the donor proteins enabled them to be clearly observed in spectra in the presence of significant amounts of the high molecular weight cd1. Mixtures of the physiological donor (Pseudomonas ferrocytochrome c-551) and ferrocytochrome cd1 showed specific line-broadening effects on the resonances of c-551 that depended on the mole ratio of c-551 to cd1. The experimental broadening fit a model in which c-551 is in intermediate or fast exchange between free solution and a complex with cd1, with an association constant for the complex in excess of 10(4) M-1. The model yields a minimum estimate for the forward bimolecular rate constant of 5 X 10(7) M-1 s-1 and suggests that the actual value may be much larger. The complexation was independent of pH in the range of 6-8, was independent of ionic strength over a salt concentration range of 20-1000 mM, and possessed a low thermal activation barrier. Mixtures of ferricytochrome c-551 and ferricytochrome cd1 showed no observable NMR perturbations, indicating that any hypothetical complex involving the oxidized forms must follow different dynamical and/or equilibrium conditions. No observable NMR perturbations existed in spectra of mixtures of cd1 and mammalian cytochrome c or Pseudomonas azurin in either oxidation state.
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PMID:1H NMR investigation of cytochrome cd1: complexes with electron-donor proteins. 300 18


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