Hanna Strzelecka-Gołaszewska | Nencki Institute of Experimental Biology (original) (raw)
Papers by Hanna Strzelecka-Gołaszewska
Results and Problems in Cell Differentiation, 2001
European Journal of Biochemistry, 1979
Biochemical Journal, 1996
The influence of DNase I binding to Ca-ATP-G-actin and of Ca# + \Mg# + and ATP\ADP exchange on th... more The influence of DNase I binding to Ca-ATP-G-actin and of Ca# + \Mg# + and ATP\ADP exchange on the conformation of Gactin were investigated by measuring the fluorescence of dansyl cadaverine (DC) conjugated to Gln%" in subdomain 2 of the protein. Fluorescence resonance energy transfer (FRET) between this probe and N-[4-(dimethylamino)-3,5-dinitrophenyl]maleimide (DDPM) attached to Cys$(% in subdomain 1 was also measured. Contrary to an earlier report [the distance between these probes did not change significantly when DNase I was bound to actin. A small but reproducible increase in the quantum yield and a blue shift of the
The Biochemical journal, 1993
Homogeneous preparations of actin devoid of the three C-terminal residues were obtained by digest... more Homogeneous preparations of actin devoid of the three C-terminal residues were obtained by digestion of G-actin with trypsin after blocking proteolysis at other sites by substitution of Mg2+ for the tightly bound Ca2+. Removal of the C-terminal residues resulted in the following: an enhancement of the Mg(2+)-induced hydrolysis of ATP in low-ionic-strength solutions of actin; an increase in the critical concentration for polymerization; a decrease in the initial rate of polymerization; and an enhancement of the steady-state exchange of subunits in the polymer. Electron microscopy indicated an increased fragility of the filaments assembled from truncated actin. The results suggest that removal of the C-terminal residues increases the rate constants for monomer dissociation from the polymer ends and from the oligomeric species.
The Biochemical journal, Jan 15, 1995
Truncated derivatives of actin devoid of either the last two (actin-2C) or three residues (actin-... more Truncated derivatives of actin devoid of either the last two (actin-2C) or three residues (actin-3C) were used to study the role of the C-terminal segment in the polymerization of actin. The monomer critical concentration and polymerization rate increased in the order: intact actin < actin-2C < actin-3C. Conversely, the rate of hydrolysis of actin-bound ATP during spontaneous polymerization of Mg-actin decreased in the same order, so that, for actin-3C, the ATP hydrolysis significantly lagged behind the polymer growth. Probing the conformation of the nucleotide site in the monomer form by measuring the rates of the bound nucleotide exchange revealed a similar change upon removal of either the two or three residues from the C-terminus. The C-terminal truncation also resulted in a slight decrease in the rate of subtilisin cleavage of monomeric actin within the DNAse-I binding loop, whereas in F-actin subunits the susceptibility of this and of another site within this loop, speci...
Biochimica et Biophysica Acta (BBA) - Protein Structure, 1973
International Journal of Biochemistry, 1979
... 358 BARBARA PLISZKA, ADAM SZPACENKO and HANNA STRZELECKA-GOI.ASZEWSKA comparing other propert... more ... 358 BARBARA PLISZKA, ADAM SZPACENKO and HANNA STRZELECKA-GOI.ASZEWSKA comparing other properties of the frog myosin prep-arations with ... BARANY M.. BARANY K. &BAILIN G. (1968) Reactivity of actomyosin and myosin with l-fluoro-2.4-dinitroben-zene in ...
European Journal of Biochemistry, 1993
Actin can be specifically cleaved between residues 42 and 43 with a novel protease from Escherich... more Actin can be specifically cleaved between residues 42 and 43 with a novel protease from Escherichia coli A2 strain (ECP) [Khaitlina, S. Y., Collins, J. H., Kuznetsova, I. M., Pershina, V. P., Synakevich, I. G., Turoverov, K. K. & Usmanova, A. M. (1991) FEBS Lett. 279, 49-51]. The resulting C-terminal and N-terminal fragments remained associated to one another in the presence of either Ca" or Mg". The protease-treated actin was, however, neither able to spontaneously assemble into filaments nor to copolymerize with intact actin unless its tightly bound Caz+ was replaced with Mg". Substitution of Mg2+ for the bound Ca2+ was also necessary to partially restore the ability of the protease-treated actin to inhibit the DNase I activity.
European Journal of Biochemistry, 1993
Abbreviations. IAEDANS, N-iodoacetyl-N-(5-sulfo-l-naph-thy1)ethylenediamine; NBD, 7-chloro-4-nitr... more Abbreviations. IAEDANS, N-iodoacetyl-N-(5-sulfo-l-naph-thy1)ethylenediamine; NBD, 7-chloro-4-nitrobenzeno-2-oxa-1,3diazole ; FITC, fluorescein-5-isothiocyanate;
European Journal of Biochemistry, 1978
European Journal of Biochemistry, 1987
Tryptic digestion patterns reveal a close similarity of the substructure of frog subfragment-1 (S... more Tryptic digestion patterns reveal a close similarity of the substructure of frog subfragment-1 (Sl) to that established for rabbit S1. The 97-kDa heavy chain of chymotryptic S1 of frog myosin is preferentially cleaved into three fragments with apparent molecular masses of 29 kDa, 49 kDa and 20 kDa. These fragments correspond to the 27-kDa, 50-kDa and 20-kDa fragments of rabbit S1, respectively; this is indicated by the sequence of their appearance during digestion, by the suppression by actin of the generation of the 49-kDa and 20-kDa peptides, and by a nucleotide-promoted cleavage of the 29-kDa peptide to a 24-kDa fragment and the 49-kDa peptide to a 44-kDa fragment, analogous to the nucleotide-promoted cleavage of the 27-kDa and 50-kDa fragments of rabbit S1 to the 22-kDa and 45-kDa peptides.
European Journal of Biochemistry, 1978
The effect of various divalent cations on the state of aggregation of actin monomers has been stu... more The effect of various divalent cations on the state of aggregation of actin monomers has been studied at pH 7.6 by means of viscosity measurements, determination of the protein sedimenting at high and low centrifugal forces, dephosphorylation of the actin-bound ATP and by observation of the negatively stained preparations under the electron microscope. The metal concentration dependence of the degree of actin polymerization in the presence of Ca2', Mg", Sr2' and Mn" is the same. All these cations produce typical double-stranded F-actin filaments. Ni2' and Zn2+ induce polymerization at lower concentrations than Mn2' and alkaline earth metals, but the resultant polymers have lower viscosities. Examination in the electron microscope has shown that Ni2' produces typical F-actin filaments, which, however, tend to brake into short fragments. In the presence of Zn2+ globular aggregates coexisting with the filaments have been observed.
European Journal of Biochemistry, 1975
Exchangeability of actin-bound ADP and calcium in actomyosin at low ionic strength has been studi... more Exchangeability of actin-bound ADP and calcium in actomyosin at low ionic strength has been studied using F-actin labelled with [14C]ADP or 45Ca and measuring release of radioactivity into solution. Low-speed centrifugation, ultracentrifugation and ultrafiltration were used to separate protein from the medium. Comparison of the results obtained with these three separation procedures has revealed that the release of [14C]ADP and 45Ca into the medium in the presence of millimolar concentrations of MgATP is largely due to the release under these conditions of actin itself retaining its bound ADP and calcium. The real exchange of the bound nucleotide and calcium, even under the most favourable conditions, was in our experiments limited to about 20%. Detailed examination of the dependence of both the release of actin and the exchange of actin-bound ADP and calcium on the free divalent cations present, the kind and concentration of the added nucleotide, and temperature of incubation indicates that there is no correlation between the exchange and superprecipitation of actomyosin. The results presented support the view that the limited enhancement by myosin of the exchange of nucleotide and cation bound to actin under certain conditions results from accidental disruption of bonds between actin monomers due to a mechanical stress exerted on actin filaments upon their interaction with myosin filaments.
European Journal of Biochemistry, 1980
Preparations of chicken gizzard actin obtained from acetone-dried muscle powders prepared with va... more Preparations of chicken gizzard actin obtained from acetone-dried muscle powders prepared with various methods developed for skeletal muscle contain variable amounts of a P-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 8-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.
European Journal of Biochemistry, 1973
The effects of various divalent cations on the rate of exchange of G-actin-bound ATP and on the r... more The effects of various divalent cations on the rate of exchange of G-actin-bound ATP and on the rate of dissociation of ATP from G-actin under conditions of a continuous removal of free ATP from the protein solution by Dowex-I were investigated. The order of inhibitory effects of equal concentrations of various cations on the ATP-exchange rate did not parallel the order of affinities of the cations to the high affinity binding site in actin, inconsistent with what was expected on the basis of earlier findings. A kinetic analysis of the exchange of ATP in G-actin preparations containing either Ca2+ or Mg2+ as the bound cation in the presence of various concentrations of the respective free cation revealed that the rate constants governing the equilibria between free and bound ATP in G-actin solutions are markedly influenced by the kind of the G-actin-bound cation. The dependence of the rate of release of the bound ATP during incubation with Dowex-1 on the kind of the bound cation (Ca2+, Mga+ or Mna+) led to the same conclusion. L t is suggested that the conformation of the ATP binding site depends upon the cation bound a t the high affinity site in actin.
European Journal of Biochemistry, 1988
The effects of temperature, Mg", ATP, and actin on the conformation of the neck region of the myo... more The effects of temperature, Mg", ATP, and actin on the conformation of the neck region of the myosin head were studied by limited proteolysis of heavy meromyosin (HMM) and subfragment 1 (Sl) preparations obtained by papain digestion of myosin in the presence of Mg2+ (Mg-S1) or EDTA (EDTA-Sl). The preparations were fluorescently labelled at the SH1 thiol group to enable identification of the COOH-terminal fragments of the head portion of the heavy chain where this group is located.
European Journal of Biochemistry, 1988
The rotational motions of the actin from rabbit skeletal muscle and from chicken gizzard smooth m... more The rotational motions of the actin from rabbit skeletal muscle and from chicken gizzard smooth muscle were measured by conventional and saturation transfer electron paramagnetic resonance (EPR) spectroscopy using maleimide spin-label rigidly bound at Cys-374. The conventional EPR spectra indicate a slight difference in the polarity of the environment of the label and in the rotational mobility of the monomeric gizzard actin compared to its skeletal muscle counterpart. These differences disappear upon polymerization. The EPR spectra of the two actins in their F form and in their complexes with heavy meromyosin (HMM) did not reveal any difference in the rotational dynamic properties that might be correlated with the known differences in the activation of myosin ATPase activity by smooth and skeletal muscle actin.
European Journal of Biochemistry, 1990
It was previously shown that tryptic digestion of subfragment 1 (Sl) of skeletal muscle myosins a... more It was previously shown that tryptic digestion of subfragment 1 (Sl) of skeletal muscle myosins at 0°C results in cleavage of the heavy chain at a specific site located 5 kDa from the NH,-terminus. This cleavage is enhanced by nucleotides and suppressed by actin and does not occur at 25"C, except in the presence of nucleotide. Here we show a similar temperature sensitivity and protection by actin of an analogous chymotryptic cleavage site in the heavy chain of gizzard S1. The results support the view that the myosin head, in general, can exist in two different conformational states even in the absence of nucleotides and actin, and indicate that the heavy chain region 5 kDa from the NH,-terminus is involved in the communication between the sites of nucleotide and actin binding.
European Journal of Biochemistry, 2005
Interaction of actin from chicken gizzard and from rabbit skeletal muscle with rabbit skeletal mu... more 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.
Results and Problems in Cell Differentiation, 2001
European Journal of Biochemistry, 1979
Biochemical Journal, 1996
The influence of DNase I binding to Ca-ATP-G-actin and of Ca# + \Mg# + and ATP\ADP exchange on th... more The influence of DNase I binding to Ca-ATP-G-actin and of Ca# + \Mg# + and ATP\ADP exchange on the conformation of Gactin were investigated by measuring the fluorescence of dansyl cadaverine (DC) conjugated to Gln%" in subdomain 2 of the protein. Fluorescence resonance energy transfer (FRET) between this probe and N-[4-(dimethylamino)-3,5-dinitrophenyl]maleimide (DDPM) attached to Cys$(% in subdomain 1 was also measured. Contrary to an earlier report [the distance between these probes did not change significantly when DNase I was bound to actin. A small but reproducible increase in the quantum yield and a blue shift of the
The Biochemical journal, 1993
Homogeneous preparations of actin devoid of the three C-terminal residues were obtained by digest... more Homogeneous preparations of actin devoid of the three C-terminal residues were obtained by digestion of G-actin with trypsin after blocking proteolysis at other sites by substitution of Mg2+ for the tightly bound Ca2+. Removal of the C-terminal residues resulted in the following: an enhancement of the Mg(2+)-induced hydrolysis of ATP in low-ionic-strength solutions of actin; an increase in the critical concentration for polymerization; a decrease in the initial rate of polymerization; and an enhancement of the steady-state exchange of subunits in the polymer. Electron microscopy indicated an increased fragility of the filaments assembled from truncated actin. The results suggest that removal of the C-terminal residues increases the rate constants for monomer dissociation from the polymer ends and from the oligomeric species.
The Biochemical journal, Jan 15, 1995
Truncated derivatives of actin devoid of either the last two (actin-2C) or three residues (actin-... more Truncated derivatives of actin devoid of either the last two (actin-2C) or three residues (actin-3C) were used to study the role of the C-terminal segment in the polymerization of actin. The monomer critical concentration and polymerization rate increased in the order: intact actin < actin-2C < actin-3C. Conversely, the rate of hydrolysis of actin-bound ATP during spontaneous polymerization of Mg-actin decreased in the same order, so that, for actin-3C, the ATP hydrolysis significantly lagged behind the polymer growth. Probing the conformation of the nucleotide site in the monomer form by measuring the rates of the bound nucleotide exchange revealed a similar change upon removal of either the two or three residues from the C-terminus. The C-terminal truncation also resulted in a slight decrease in the rate of subtilisin cleavage of monomeric actin within the DNAse-I binding loop, whereas in F-actin subunits the susceptibility of this and of another site within this loop, speci...
Biochimica et Biophysica Acta (BBA) - Protein Structure, 1973
International Journal of Biochemistry, 1979
... 358 BARBARA PLISZKA, ADAM SZPACENKO and HANNA STRZELECKA-GOI.ASZEWSKA comparing other propert... more ... 358 BARBARA PLISZKA, ADAM SZPACENKO and HANNA STRZELECKA-GOI.ASZEWSKA comparing other properties of the frog myosin prep-arations with ... BARANY M.. BARANY K. &BAILIN G. (1968) Reactivity of actomyosin and myosin with l-fluoro-2.4-dinitroben-zene in ...
European Journal of Biochemistry, 1993
Actin can be specifically cleaved between residues 42 and 43 with a novel protease from Escherich... more Actin can be specifically cleaved between residues 42 and 43 with a novel protease from Escherichia coli A2 strain (ECP) [Khaitlina, S. Y., Collins, J. H., Kuznetsova, I. M., Pershina, V. P., Synakevich, I. G., Turoverov, K. K. & Usmanova, A. M. (1991) FEBS Lett. 279, 49-51]. The resulting C-terminal and N-terminal fragments remained associated to one another in the presence of either Ca" or Mg". The protease-treated actin was, however, neither able to spontaneously assemble into filaments nor to copolymerize with intact actin unless its tightly bound Caz+ was replaced with Mg". Substitution of Mg2+ for the bound Ca2+ was also necessary to partially restore the ability of the protease-treated actin to inhibit the DNase I activity.
European Journal of Biochemistry, 1993
Abbreviations. IAEDANS, N-iodoacetyl-N-(5-sulfo-l-naph-thy1)ethylenediamine; NBD, 7-chloro-4-nitr... more Abbreviations. IAEDANS, N-iodoacetyl-N-(5-sulfo-l-naph-thy1)ethylenediamine; NBD, 7-chloro-4-nitrobenzeno-2-oxa-1,3diazole ; FITC, fluorescein-5-isothiocyanate;
European Journal of Biochemistry, 1978
European Journal of Biochemistry, 1987
Tryptic digestion patterns reveal a close similarity of the substructure of frog subfragment-1 (S... more Tryptic digestion patterns reveal a close similarity of the substructure of frog subfragment-1 (Sl) to that established for rabbit S1. The 97-kDa heavy chain of chymotryptic S1 of frog myosin is preferentially cleaved into three fragments with apparent molecular masses of 29 kDa, 49 kDa and 20 kDa. These fragments correspond to the 27-kDa, 50-kDa and 20-kDa fragments of rabbit S1, respectively; this is indicated by the sequence of their appearance during digestion, by the suppression by actin of the generation of the 49-kDa and 20-kDa peptides, and by a nucleotide-promoted cleavage of the 29-kDa peptide to a 24-kDa fragment and the 49-kDa peptide to a 44-kDa fragment, analogous to the nucleotide-promoted cleavage of the 27-kDa and 50-kDa fragments of rabbit S1 to the 22-kDa and 45-kDa peptides.
European Journal of Biochemistry, 1978
The effect of various divalent cations on the state of aggregation of actin monomers has been stu... more The effect of various divalent cations on the state of aggregation of actin monomers has been studied at pH 7.6 by means of viscosity measurements, determination of the protein sedimenting at high and low centrifugal forces, dephosphorylation of the actin-bound ATP and by observation of the negatively stained preparations under the electron microscope. The metal concentration dependence of the degree of actin polymerization in the presence of Ca2', Mg", Sr2' and Mn" is the same. All these cations produce typical double-stranded F-actin filaments. Ni2' and Zn2+ induce polymerization at lower concentrations than Mn2' and alkaline earth metals, but the resultant polymers have lower viscosities. Examination in the electron microscope has shown that Ni2' produces typical F-actin filaments, which, however, tend to brake into short fragments. In the presence of Zn2+ globular aggregates coexisting with the filaments have been observed.
European Journal of Biochemistry, 1975
Exchangeability of actin-bound ADP and calcium in actomyosin at low ionic strength has been studi... more Exchangeability of actin-bound ADP and calcium in actomyosin at low ionic strength has been studied using F-actin labelled with [14C]ADP or 45Ca and measuring release of radioactivity into solution. Low-speed centrifugation, ultracentrifugation and ultrafiltration were used to separate protein from the medium. Comparison of the results obtained with these three separation procedures has revealed that the release of [14C]ADP and 45Ca into the medium in the presence of millimolar concentrations of MgATP is largely due to the release under these conditions of actin itself retaining its bound ADP and calcium. The real exchange of the bound nucleotide and calcium, even under the most favourable conditions, was in our experiments limited to about 20%. Detailed examination of the dependence of both the release of actin and the exchange of actin-bound ADP and calcium on the free divalent cations present, the kind and concentration of the added nucleotide, and temperature of incubation indicates that there is no correlation between the exchange and superprecipitation of actomyosin. The results presented support the view that the limited enhancement by myosin of the exchange of nucleotide and cation bound to actin under certain conditions results from accidental disruption of bonds between actin monomers due to a mechanical stress exerted on actin filaments upon their interaction with myosin filaments.
European Journal of Biochemistry, 1980
Preparations of chicken gizzard actin obtained from acetone-dried muscle powders prepared with va... more Preparations of chicken gizzard actin obtained from acetone-dried muscle powders prepared with various methods developed for skeletal muscle contain variable amounts of a P-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 8-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.
European Journal of Biochemistry, 1973
The effects of various divalent cations on the rate of exchange of G-actin-bound ATP and on the r... more The effects of various divalent cations on the rate of exchange of G-actin-bound ATP and on the rate of dissociation of ATP from G-actin under conditions of a continuous removal of free ATP from the protein solution by Dowex-I were investigated. The order of inhibitory effects of equal concentrations of various cations on the ATP-exchange rate did not parallel the order of affinities of the cations to the high affinity binding site in actin, inconsistent with what was expected on the basis of earlier findings. A kinetic analysis of the exchange of ATP in G-actin preparations containing either Ca2+ or Mg2+ as the bound cation in the presence of various concentrations of the respective free cation revealed that the rate constants governing the equilibria between free and bound ATP in G-actin solutions are markedly influenced by the kind of the G-actin-bound cation. The dependence of the rate of release of the bound ATP during incubation with Dowex-1 on the kind of the bound cation (Ca2+, Mga+ or Mna+) led to the same conclusion. L t is suggested that the conformation of the ATP binding site depends upon the cation bound a t the high affinity site in actin.
European Journal of Biochemistry, 1988
The effects of temperature, Mg", ATP, and actin on the conformation of the neck region of the myo... more The effects of temperature, Mg", ATP, and actin on the conformation of the neck region of the myosin head were studied by limited proteolysis of heavy meromyosin (HMM) and subfragment 1 (Sl) preparations obtained by papain digestion of myosin in the presence of Mg2+ (Mg-S1) or EDTA (EDTA-Sl). The preparations were fluorescently labelled at the SH1 thiol group to enable identification of the COOH-terminal fragments of the head portion of the heavy chain where this group is located.
European Journal of Biochemistry, 1988
The rotational motions of the actin from rabbit skeletal muscle and from chicken gizzard smooth m... more The rotational motions of the actin from rabbit skeletal muscle and from chicken gizzard smooth muscle were measured by conventional and saturation transfer electron paramagnetic resonance (EPR) spectroscopy using maleimide spin-label rigidly bound at Cys-374. The conventional EPR spectra indicate a slight difference in the polarity of the environment of the label and in the rotational mobility of the monomeric gizzard actin compared to its skeletal muscle counterpart. These differences disappear upon polymerization. The EPR spectra of the two actins in their F form and in their complexes with heavy meromyosin (HMM) did not reveal any difference in the rotational dynamic properties that might be correlated with the known differences in the activation of myosin ATPase activity by smooth and skeletal muscle actin.
European Journal of Biochemistry, 1990
It was previously shown that tryptic digestion of subfragment 1 (Sl) of skeletal muscle myosins a... more It was previously shown that tryptic digestion of subfragment 1 (Sl) of skeletal muscle myosins at 0°C results in cleavage of the heavy chain at a specific site located 5 kDa from the NH,-terminus. This cleavage is enhanced by nucleotides and suppressed by actin and does not occur at 25"C, except in the presence of nucleotide. Here we show a similar temperature sensitivity and protection by actin of an analogous chymotryptic cleavage site in the heavy chain of gizzard S1. The results support the view that the myosin head, in general, can exist in two different conformational states even in the absence of nucleotides and actin, and indicate that the heavy chain region 5 kDa from the NH,-terminus is involved in the communication between the sites of nucleotide and actin binding.
European Journal of Biochemistry, 2005
Interaction of actin from chicken gizzard and from rabbit skeletal muscle with rabbit skeletal mu... more 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.