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

Subfragment-1 prepared by chymotryptic digestion of myosin was applied to a column of Sepharose-adipic acid hydrazide-ATP in 1 mM EDTA, 10 mM Tris-HCL (PH 7.6), and 40 mM KCL. Ninety-nine per cent of subfragment-1 was adsorbed on the column in this medium. Fourty-three per cent of the applied protein was eluted with 6 mM ADP in the above buffer and then 52% was eluted with 1 mM EDTA, 10 mM Tris-HCL (pH 7.6), AND 0.7 M KCL. The former fraction contained g3 chain and the latter g1 chain. These fractions were apparently the same as the components, p2 and p1, respectively, isolated by ion-exchange chromatography using DEAE-cellulose (Yagi & Otani (1974) J. Biochem. 76, 365-373). No significant difference of ADP binding was found between the two fractions, both could bind about 0.5 mole per 10(5) g of protein. The preparation of the two subfragment-1 fractions is described.
 ...
PMID:Separation of myosin subfragment-1 into fractions containing g1 chani and g2 chain by Sepharose-adipic acid hydrazide-ATP column chromatography. 95 34

Myosin messenger ribonucleoprotein-translational control ribonucleic acid (mRNP-tcNA) from myosin mRNPs found in embryonic chick muscle has been further purified by Dowex chromatography and, from a number of controls, it is suggested that this small RNA is not an artifact produced through the degradation of RNA during its isolation. This highly purified myosin mRNP-tcRNA is shown to have a molecular weight of 10 000 on formamide-acrylamide gels, and reacts stoichometrically (on a 1:1 mole ratio) with myosin mRNA. The stoichiometric interaction between myosin mRNA and myosin mRNP-tcRNP is demonstrated by ists ability to increase the nuclease resistance of the messenger, as well as inhibit its translation in a cell-free amino acid incorporating system.
 ...
PMID:Purification of myosin translational control RNA and its interaction with myosin messenger RNA. 98 57

The association constant for myosin subfragment-1 (S-1) and actin was measured, using a new application of fluorescence depolarization which capitalizes on the fact that S-1 has high rotational mobility while F-actin does not. Uncoupling of the time dependences of the anisotropy decay and the association/dissociation phenomena allowed the experimentally determined anisotropy decay curve to be fitted by a sum of two terms weighted by the mole fractions of the free and bound S-1. At 4 degrees C, ionic strength 0.16 M, and pH 7.0, the association constant Ka is (1.73 +/- 0.35) X 10(6) M-1 at infinite dilution. This makes the -deltaG degrees of binding of F-actin to S-1 similar to the -deltaG degrees of binding of ATP to S-1, and the possible physiological relevance of the similarity to muscle contraction is discussed.
 ...
PMID:Affinity of myosin S-1 for F-actin, measured by time-resolved fluorescence anisotropy. 106 Nov 7

We report measurements of the reactivity (degree of labeling, as mole of ligand per mole of protein, at constant exposure time) of the reactive thiol, "SH1", of a subfragment of myosin (S-1), and of Cys-10 of F-actin under various conditions, using N-iodo-[3H]acetyl-N-(1-sulfo-5-naphthyl)ethylenediamine, a fluorescent radioactive iodoacetamide analog. When either ADP or adenyloyl imidodiphosphate (simulating unhydrolyzed ATP) is bound to the enzymatic site of S-1, the reactivity of "SH1" is slightly enhanced, but when active ATPase is going on, reactivity is reduced by about a third, presumably due to the species, (S-1) ADP,Pi. The reactivity of Cys-10 alone is very low. When the complex, (S-1)-F-actin, is formed, the reactivity of SH1 is strongly decreased, and the reactivity of Cys-10 is strongly increased. The foregoing results explain our further observation (on glycerol-treated rabbit psoas fibers) that when fibers labeled in relaxation solution are compared with fibers labeled in rigor solution, myosin is more reactive and actin is less reactive, in the former case; alpha-actinin and C-protein are also less reactive in the former case.
 ...
PMID:Reciprocal reactivities of specific thiols when actin binds to myosin. 106 Nov 33

Low molecular weight components (g1, g2, and g3) were isolated from rabbit skeletal muscle myosin and their amino acid compositions were analyzed. One mole tryptophan was found in g1 and in g2, but none in g3. One mole of acetic acid was found per mole of each g-chain and it was concluded that the N-terminal groups of all three g-chains are acetylated. The minimum molecular weight of the g-chains were estimated from their amino acid compositions. It was estimated by SDS-disc electrophoresis that 1 mole of myosin contained 0.90, 1.7, and 0.63 moles of g1, g2, and g3, respectively. Similar values were obtained with psoas muscle myosin, but in heavy meromyosin prepared from skeletal muscle myosin the content of g2 was much lower, and that of g3 was much higher.
 ...
PMID:Low molecular weight components (g-chains) of myosin from rabbit skeletal muscle. Separation, amino acid compositions and contents in myosin. 112 22

A synthetic peptide corresponding to a sequence 632-642 (S632-642) on the myosin subfragment 1 (S-1) heavy chain and spanning the 50/20 kDa junction of S-1 binds to actin in the presence and absence of S-1. The binding of 1.0 mole of peptide per actin causes almost complete inhibition of actomyosin ATPase activity and only partial inhibition of S-1 binding to actin. The binding of S632-642 to the N-terminal segment of actin is supported by competitive carbodiimide cross-linking of S-1 and S632-642 to actin and the catalytic properties of cross-linked acto-S-1 and actin-peptide complexes. These results show that the sequence 632-642 on S-1 is an autonomous binding site for actin and confirm the catalytic importance of its interactions with the N-terminal segment of actin.
 ...
PMID:Synthetic peptide of the sequence 632-642 on myosin subfragment 1 inhibits actomyosin ATPase activity. 147 24

The effect of temperature on the velocity of rhodamine phalloidin-labelled F-actin moving in vitro on rabbit skeletal myosin has been studied. Translating actin filaments were visualized by epi-fluorescence in an inverted microscope, equipped with temperature control (+/- 0.2 K) of the stage and objective. Images were recorded in real time at magnifications of 400x or 160x by an intensified CCD camera on video tape. Motion of individual filaments was tracked by hand and velocities determined using frame times recorded simultaneously on the video tape. Velocity changed from 12 microns per second at 42 degrees C to 11 nm per second at 3 degrees C. The Arrhenius plot is non-linear, with the data following a cubic regression curve with no evident breaks or jumps. Data taken over the temperature range from single preparations followed the same curve for both heating and cooling; this indicates reversibility and absence of hysteresis. A hyperbolic model that smoothly translates with temperature between two asymptotic activation energies fits the data above 7 degrees C: these energies are 50(+/- 5) kJ per mole (Q10 = 1.9) at high temperatures and 289(+/- 29) kJ per mole (Q10 = 76.5) at low temperature with a transition temperature of 15.4(+/- 0.6) degrees C. These values are compared with other measurements made in vitro, in solution studies and on muscle fibres. An Arrhenius activation energy of 50 kJ per mole and a transition temperature of 15 degrees C are consistent with previous determinations but 289 kJ per mole is significantly greater than has been seen at low temperatures in other systems. This may indicate a different rate-limiting step in the kinetics of skeletal myosin driving actin filaments in vitro below 15 degrees C. Current determinations of the myosin "step-size" assume that the actin velocity is determined by the rate of ATP hydrolysis; the data confirm similar activation energies above 20 degrees C but they show that the temperature dependencies and activation energies are different at lower temperatures, implying uncoupling of the two processes.
 ...
PMID:Temperature dependence and Arrhenius activation energy of F-actin velocity generated in vitro by skeletal myosin. 153 50

Adsorption isotherms of BSA at the solid-water interfaces have been studied as a function of protein concentration, ionic strength of the medium, pH and temperature using silica, barium sulphate, carbon, alumina, chromium, ion-exchange resins and sephadex as solid interfaces. In most cases, isotherms for adsorption of BSA attained the state of adsorption saturation. In the presence of barium sulphate, carbon and alumina, two types in the isotherms are observed. Adsorption of BSA is affected by change in pH, ionic strength and temperature of the medium. In the presence of metallic chromium, adsorbed BSA molecules are either denatured or negatively adsorbed at the metallic interface. Due to the presence of pores in ion-exchange resins, adsorption of BSA is followed by preferential hydration on resin surfaces in some cases. Sometimes two steps of isotherms are also observed during adsorption of BSA on the solid resins in chloride form. Adsorption of BSA, beta-lactoglobulin, gelatin, myosin and lysozyme is negative on Sephadex surface due to the excess adsorption of water by Sephadex. The negative adsorption is significantly affected in the presence of CaCl2, KSCN, LiCl, Na2SO4, NaI, KCl and urea. The values of absolute amounts of water and protein, simultaneously adsorbed on the surface of different solids, have been evaluated in some cases on critical thermodynamic analysis. The standard free energies (delta G0) of excess positive and negative adsorption of the protein per square meter at the state of monolayer saturation have been calculated using proposed universal scale of thermodynamics. The free energy of adsorption with reference to this state is shown to be strictly comparable to each other. The magnitude of standard free energy of transfer (delta G0B) of one mole of protein or a protein mixture at any type of physiochemical condition and at any type of surface is observed to be 38.5 kJ/mole.
 ...
PMID:Protein adsorption at solid-liquid interfaces: Part IV--Effects of different solid-liquid systems and various neutral salts. 175 29

Extent of adsorption (gamma pw) of bovine serum albumin, beta-lactoglobulin, gelatin and myosin at the alumina-water interface has been measured as function of protein concentration (Cp) at several temperatures, pH, and ionic strengths of the medium. gamma pw for proteins in most cases increases with increase of protein concentration but it attains maximum value gamma pw(m) when Cp is high. Values of maximum adsorption have been examined in terms of molecular orientation, molecular size and shape and unfolding of the packed proteins at the interface. In few cases, gamma pw increases with increase of Cp without reaching a real state of saturation as a result of aggregation of molecules or extensive unfolding of the protein at the interface. In the case of beta-lactoglobulin at pH 5.2 and ionic strength 0.05, gamma pw in high concentration region decreases to zero value when Cp increases. For myosin at 45 degrees C and pH 6.4, and also at 27 degrees and pH 7.8, the values of gamma pw are all negative and these negative values increase with increase of Cp. All these results have been explained in terms of significant competitions of water and protein for binding to the surface sites of the powdered alumina. Adsorption of myosin has also been found to be affected in the presence of NaCl, KCl, CaCl2, KI, Na2SO4, LiCl and urea. The relative affinities of the adsorption of various proteins for the surface of alumina at different physical conditions of the system have been compared in terms of maximum values of adsorption attained when gamma pw is varied with Cp. The affinities are shown to be compared more precisely in terms of the standard free energy decrease for the saturation of the surface by protein as a result of the change in its concentration from zero to unity in the mole fraction scale.
 ...
PMID:Protein adsorption at solid-liquid interfaces: Part I--Affinities of proteins for alumina surface. 187 68

K(+)-contracted porcine carotid arterial muscles containing phosphorylated 20-kDa myosin light chains (LC) were exposed to carrier-free [32P]orthophosphate in K(+)-stimulating solution during sustained contraction. The covalently bound LC phosphate was completely replaced by [32P]phosphate, indicating that myosin light chain phosphatase and kinase have ready access to the bound phosphate during the sustained contraction. On average, 0.38 mol [32P]phosphate was incorporated per mole LC during the sustained K+ contraction. This value was about half of the maximal value for [32P]phosphate incorporation into LC, 0.74 mol/mol, in muscles contracted with K+ for 1 min. Assuming that sustained contraction involves the maximal number of cross-bridges attached to actin, the data suggest that half of the attached cross-bridges contain phosphorylated LC.
 ...
PMID:Exchange of 20-kDa myosin light chain-bound phosphate during sustained contraction of arterial smooth muscle. 189 90


<< Previous 1 2 3 4 5 6 7 8 9 Next >>