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821.
Summary The authors examined the karyotypes of the men 183 cm (6 ft.) tall or more among the 320 male residents of two Swedish institutions for the long-term care of epilepsy. All 14 men meeting this criterion proved to have the normal chromosome constitution-46, XY. 相似文献
822.
A 23 kDa protein has recently been demonstrated to participate in photosynthetic oxygen evolution by reconstitution experiments on inside-out thylakoid vesicles (Åkerlund H-E, Jansson C and Andersson B (1982) Biochim Biophys Acta 681:1–10). Here we describe the isolation of the 23 kDa protein from a spinach chloroplast extract using ion-exchange chromatography. The protein was obtained in a yield of 25% and with less than 1% of contaminating proteins. The ability of the protein to stimulate oxygen evolution in inside-out thylakoids was preserved throughout the various fractionation steps. The isolated protein was highly water soluble and appeared as a monomer. Its isoelectric point was at pH=7.3. The amino acid composition showed a high content of polar amino acids, resulting in a polarity index of 49%. The isolated protein lacked metals and other prosthetic groups. Its function as a catalytic or regulating subunit in the oxygen evolving complex is discussed.Abbreviations kDa
kiloDalton
- PAGE
polyacrylamide gel electrophoresis 相似文献
823.
In Acholeplasma laidlawii A, strain EF 22, the relative amounts of the membrane polar lipids vary as a consequence of different fatty acid supplements to the growth medium. The number of lipid species also varies; a new apolar monoglucolipid containing four fatty acid residues was present only when saturated fatty acids dominated in the growth medium. A new phosphoglucolipid, probably with a glycerophosphoryl-monoglucosyldiglyceride structure, was also found. The most pronounced variations occurred between the two dominating glucolipids, monoglucosyldiglyceride and diglucosyldiglyceride; the former being found in larger amounts when a saturated or a trans-unsaturated fatty acid was present in the medium. The amount of diglucosyldiglyceride decreased accordingly. A qualitative relationship between fatty acid properties and membrane lipid variations was established over a wide fatty acid concentration range. Incorporation of supplied fatty acids reached higher levels than normally found in other acholeplasmas. The ratio between membrane protein and lipids exhibited significant and coherent variations during growth and was to some extent influenced by the fatty acids in the medium. These changes indicate variations in lipid-protein organization in the membranes during growth. 相似文献
824.
Karl E.O. Åkerman Michael O. Proudlove Anthony L. Moore 《Biochemical and biophysical research communications》1983,113(1):171-177
Fluxes of Ca2+ across the plasma membrane of isolated wheat protoplasts have been measured both as net accumulation and as uptake under steady-state conditions. The ATPase inhibitors, orthovanadate and diethylstibesterol, and the divalent cation ionophore, A23187, were all found to enhance net Ca2+ accumulation by protoplasts. The uptake of Ca2+ under steady-state conditions was also stimulated by A23187 but relatively unaffected by a range of plant hormones or by red or far red light. Light treatments were compared to dark controls with protoplasts isolated from etiolated wheat.The results suggest that plant cells maintain a Ca2+ gradient across their plasma membrane but it appears not to be under phytochrome control. 相似文献
825.
The action of Mg2+ on the putative xKv1.1 channel in the myelinated axon of Xenopus laevis was analyzed in voltage clamp experiments. The main effect was a shift in positive direction of the open probability curve
(16 mV at 20 mm Mg2+), calculated from measurements of the instantaneous current at Na reversal potential after 50–100 msec steps to different
potentials. The shift was measured at an open probability level of 25% to separate it from shifts of other K channel populations
in the nodal region. The results could be explained in terms of screening effects on fixed charges located on the surface
of the channel protein. Using the Grahame equation the functional charge density was estimated to −0.45 e nm−2. Analyzing this value, together with previously estimated values from other K channels, with reference to the charge of different
extracellular loops of the channel protein, we conclude that the loop between the transmembrane S5 segment and the pore forming
P segment determines the functional charge density of voltage-gated K channels.
Received: 11 December 1997/Revised: 24 April 1998 相似文献
826.
827.
Satish Chandra Govind Simin Roumina Lars-Åke Brodin Jacek Nowak Saligrama Srinivasiah Ramesh Samir Kanti Saha 《Cardiovascular ultrasound》2006,4(1):1-9
The ninth edition of the congress of the European Association of Echocardiography (EAE) (former working group of Echocardiography) held in Florence has just finished with a great success of participant attendance (2.842) and abstract submissions. Hot topics at EuroEcho 9 were: 1-live 3-dimensional echocardiography and surgical decision making; in pediatric cardiology; in resynchronization therapy 2- stress echocardiography beyond wall motion: from valve diseases to contractility to coronary flow reserve to diastolic function; 3- pulmonary cardiogenic interstitial thickening recognized by ultrasonic lung comets; 4- the "proven clinical inefficacy" of the many technologies sold as breakthrough: color kinesis, tissue characterization, strain rate, tissue Doppler, applied to stress echocardiography. 相似文献