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E Próchniewicz

Publications and source records attributed to E Próchniewicz.

6 recordsLinked to original sources
PubMed1983

The effect of cytochalasin and glutaraldehyde on F-actin filaments containing muscle and non-muscle tropomyosin.

F-actin filaments are disrupted by the action of cytochalasin and glutaraldehyde. Muscle tropomyosin which is able to polymerize can protect F-actin against fragmentation caused by these two agents. This protective effect does not occur with nonpolymerizable, brain or carboxy-peptidase A-treated skeletal muscle tropomyosins. The protection of F-actin against the action of cytochalasin and glutaraldehyde takes place under conditions where the F-actin filaments are saturated with tropomyosin, that is, at a molar ratio of tropomyosin to actin of 1:7. It is suggested that nonpolymerizable tropomyosin lacks the protective ability because its binding to F-actin is considerably weaker than the polymerizable tropomyosin and does not saturate all of the binding sites on F-actin.

Actins↗
PubMed1980

Chicken-gizzard actin: polymerization and stability.

Preparations of chicken gizzard actin obtained from acetone-dried muscle powders prepared with various methods developed for skeletal muscle contain variable amounts of a beta-actinin-like protein. This contamination is minimized if the procedure of muscle powder preparation includes washing with EDTA solution, and can be completely removed by gel filtration of G-actin on Sephadex G-100. The presence of beta-actinin activity manifests itself in an increased rate of actin polymerization, low filament lengths resulting in low reduced viscosity and enhanced ATP-splitting activity of actin polymer, and instability of the polymer in the absence of free ATP. Gizzard actin purified on a Sephadex G-100 column does not differ from rabbit skeletal muscle actin in its polymerization properties. The distinct property of gizzard actin is the instability of its G form in the absence of added Ca2+, indicating that the affinity of this cation for the single high-affinity site in gizzard actin is lower than in skeletal muscle actin.

Actins↗
PubMed1980

Chicken-gizzard actin. Interaction with skeletal-muscle myosin.

Interaction of actin from chicken gizzard and from rabbit skeletal muscle with rabbit skeletal muscle myosin was compared by measuring the rate of superprecipitation, the activation of the Mg-ATPase and inhibition of K-ATPase activity of myosin and heavy meromyosin, and determination of binding of heavy meromyosin in the absence of ATP. Both the rate of superprecipitation of the hybrid actomyosin and the activation of myosin ATPase by gizzard actin are lower than those obtained with skeletal muscle actin. The activation of myosin Mg-ATPase by the two actin species also shows different dependence on substrate concentration: with gizzard actin the substrate inhibition starts at lower ATP concentration. The double-reciprocal plots of the Mg-ATPase activity of heavy meromyosin versus actin concentration yield the same value of the extrapolated ATPase activity at infinite actin concentration (V) for the two actins and nearly double the actin concentration needed to produce half-maximal activation (Kapp) in the case of gizzard actin. A corresponding difference in the abilities of the two actin species to inhibit the K-ATPase activity of heavy meromyosin in the absence of divalent cations was also observed. The results are discussed in terms of the effect of substitutions in the amino acid sequence of gizzard and skeletal muscle actins on their interaction with myosin.

Actins↗
PubMed1979

Effect of crosslinking by glutaraldehyde on interaction of F-actin with heavy meromyosin.

Crosslinking of F-actin by a bifunctional reagent glutaraldehyde resulted in a marked decrease of viscosity and length of F-actin filaments. The extent and rate of superprecipitation of actomyosin reconstituted from the modified actin were lower than those of unmodified actin-myosin complex, but activation of heavy meromyosin ATPase by the crosslinked actin was higher than by unmodified one. Heavy meromyosin ATPase activated by the crosslinked actin was distinctly less dependent on KCl concentration than that activated by unmodified actin. Turbidity of the modified acto-heavy meromyosin in the presence of ATP exceeded the sum of turbidities of actin and heavy meromyosin, whereas in the case of unmodified acto-heavy meromyosin the turbidity was comparable to that for noninteracting system. The difference in activation of heavy meromyosin. ATPase by the cross-linked and unmodified actin, clearly seen at room temperature, significantly diminished when temperature was lowered to 0 degrees C.

Actins↗