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Biomedical subjects

J Wikman-Coffelt

Publications and source records attributed to J Wikman-Coffelt.

At least 109 records · Page 6Linked to original sources
PubMed1979

Dissociation and reassociation of rabbit skeletal muscle myosin.

Whereas dissociation of rabbit skeletal muscle myosin light chains occurs at an increased temperature (25 degrees) and in the absence of divalent cations, reassociation of the myosin oligomer requires a low temperature (4 degrees C) and the presence of divalent cations, thus resulting in the original light to heavy chain stoichiometry. With a 5-10 per cent release of alkali light chains, LC1 and LC3, and a 50 per cent dissociation of the Ca2+ binding light chain, LC2, there is no significant decrease in myosin ATPase activity irrespective of the cation activator, however, there is an approximate 15-20 per cent decrease in actomyosin ATPase activity. With reassociation of the myosin oligomer, actomyosin ATPase activity is partially restored as well as the original number of Ca2+ binding sites.

Adenosine Triphosphatases↗
PubMed1979

Studies on Ca2+-Mg2+ binding sites of frog skeletal muscle myosin.

From skeletal muscle myosin light chains readily dissociate from the myosin oligomer in the absence of divalent cations, and unlike rabbit skeletal muscle myosin light chains, the released light chains of frog skeletal muscle myosin have a high Ca2+ binding affinity. Whereas each Ca2+ binding light chain of frog skeletal muscle myosin, when in association with the heavy chains bound 1 mol of Ca2+, when in the dissociated state bound 0.5 mol of Ca2+; the latter were readily displaced with low Mg2+ concentrations. Whereas 10(-5) M Mg2+ displaced all of the Ca2+ binding sites on the released light chains at Ca2+ concentration ranges of 10(-7) to 10(-4) M, there was negligible displacement of the Ca2+ binding sites with native frog skeletal muscle myosin under these same conditions.

Animals↗
PubMed1979

Comparison of Mg2+ vs Ca2+, K+ and actin-activation of myosin after trinitrophenylation.

While modification of six lysyl residues causes a near maximal decrease in Ca2+, K+, and actin + Mg2+ -activated myosin ATPase activities in rabbit skeletal muscle myosin, it takes nearly twice this number of modified lysyl groups to cause a similar alteration in canine cardiac myosin where trinitrophenylation is nonspecific. It appears that there are several rapidly reacting lysyl residues in cardiac myosin; the active site of cardiac myosin is protected by ATP after modification of a limited number of these rapidly reacting lysyl groups. In both myosins, after a charge modification of these rapidly reacting lysyl groups, 6 in rabbit skeletal muscle myosin and 10 in canine cardiac myosin, there is a decrease in Ca2+, K+, and actin + Mg2+ -stimulation of myosin but an activation of Mg2+ -stimulated myosin ATPase activity, thus making actin + Mg2+ -stimulated myosin ATPase activity more like activation with K+ or Ca2+ as compared to activation with Mg2+ alone.

Actins↗
PubMed1978

Immunological, electrophoretic and kinetic properties of cardiac myosins from various species.

1. In a homologous radioimmunoassay for canine ventricular myosin light chains, the following percentages of cross-reactivities were obtained using the dog as a reference: human, 28%; sheep, 21%; cat, 8%; guinea-pig, 7%; rabbit, 5%; and rat, 4%. 2. In a homologous double diffusion immunoassay using specific gamma G to canine cardiac myosin heavy chains, dog cardiac myosin showed immunological identity with human and sheep cardiac myosin but partial identity with myosins of other species. 3. On a 5-20% polyacrylamide gradient, light chain C1 was electrophoretically distinct in some species; light chain C2 was electrophoretically identical in all species. 4. The K+-activated myosin ATPase of small animals was higher than that of larger animals at an alkaline pH; the same was true for Ca2+-activated myosin when assayed at pH 6.3.

Animals↗
PubMed1976

Purification of canine plasma renin by affinity chromatography.

An affinity column for the purfication of canine plasma renin was prepared using goat anti-renin (dog kidney) gammaG gloublins. The antiserum was prepared against a purified kidney renin preparation. The anti-renin globulins were coupled to cyanogen bromide activated Sepharose. Using the anti-renin globulin-coupled Sepharose as an immuno-adsorbant, a method was devised allowing purification of plasma renin to a 1,000-fold purity.

Animals↗
PubMed1975

Comparative analyses of the kinetics and subunits of myosins from canine skeletal muscle and cardiac tissue.

Two types of canine cardiac myosins, myosin from the free wall of the right ventricle and the free wall of the left ventricle, were compared with canine skeletal muscle myosin from the gastrocnemius. The Vmax values for the ATPase reaction catalyzed by myosin were significantly different among the three types of tissues. For K+-activated myosin the Vmax values in micromoles of Pi per mg per min were: right ventricle, 0.57; left ventricle, 0.72; and gastrocnemius, 0.95. For Ca-2+ -activated myosin the Vmax values were: right ventricle, 0.32; left ventricle, 0.42; gastrocnemius, 0.50. All differences were significant (p smaller than 0.001). For all three types of tissues the Vmax values for NH4+ -activated myosin were the same (2.30). Light chains among all three types of tissues were immunologically identical, whereas the heavy chains of the two cardiac ventricles were immunologically identical with each other; however both were immunologically nonidentical with those of the gastrocnemius. The proportion of myosin light chains to heavy chains was different in the three types of tissue. Of the total protein present in each of the myosins, there was 18% in the light chains of right ventricle myosin, 10% in the light chains of left ventricle myosin, and 13% in the light chains of gastrocnemius. Both left ventricle myosin and myosin from gastrocnemius had significantly less C1d light chain, as compared to myosin from the right ventricle.

Adenosine Triphosphatases↗