Journal of mechanochemistry & cell motility最新文献

{"title":"Force-length relations of glycerinated rabbit psoas.","authors":"W Hargraves,&nbsp;L Mandelkern","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>Force-length curves of glycerinated rabbit psoas were determined in media of physiological interest. In one set of experiments the free [Ca++] was constant at 10(-5) M and the [MgATP] varied. At low [MgATP] the elastic properties are those of a highly ordered, inextensible fiber; at high [MgATP] they are representative of a much more elastic body. At intermediate concentrations sigmoidal shaped curves were observed as were also found when [MgATP] was constant and the free [Ca++] varied. These curves closely resemble coexistence curves that have been reported for fibrous proteins.</p>","PeriodicalId":76011,"journal":{"name":"Journal of mechanochemistry & cell motility","volume":"3 4","pages":"235-7"},"PeriodicalIF":0.0,"publicationDate":"1976-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"12217283","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A procedure for determining mobility parameters for cells moving along surfaces.","authors":"R Nossal,&nbsp;Y T Change","doi":"","DOIUrl":"","url":null,"abstract":"","PeriodicalId":76011,"journal":{"name":"Journal of mechanochemistry & cell motility","volume":"3 4","pages":"247-51"},"PeriodicalIF":0.0,"publicationDate":"1976-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"11987652","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The myofilament lattice: studies on isolated fibers. IV. Lattice equilibria in striated muscle.","authors":"E W April","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>Accounts of similarities between the thick filament lattice of striated muscle and smectic liquid-crystalline structures have focused upon an equilibrium between electrostatic (repulsive) and van der Waal's (attractive) forces. In living, intact muscle the fiber volume constitutes an additional important parameter which influences the amount of interaxial separation between the filaments. This is demonstrable by comparison of the lattice behavior of living fibers with that of fibers from which the sarcolemma has either been removed or made leaky by glycerination. These comparisons were made mainly by low-angle X-ray diffraction under conditions of changes in sarcomere length, ionic strength or osmolarity, and pH. Single fibers with the sarcolemma removed and glycerinated muscle have lattices which behave in accord with equilibrium liquid-crystalline systems in which the thick filament spacing is determined by the balance between electrostatic and van der Waal's forces. Conversely, osmotic and shortening studies demonstrate that the living, intact muscle has a lattice which behaves in accord with the so-called non-equilibrium (volume-constrained) liquid-crystalline condition in which the interaxial separation between the thick filaments is solely due to the amount of volume available as determined by the Donnan steady-state across the sarcolemma.</p>","PeriodicalId":76011,"journal":{"name":"Journal of mechanochemistry & cell motility","volume":"3 2","pages":"111-21"},"PeriodicalIF":0.0,"publicationDate":"1975-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"11226818","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A study on the reactions of tubercidin triphosphate with myosin and actomyosin.","authors":"J P Borger,&nbsp;C A Filipenko,&nbsp;S Masamune,&nbsp;T Nihei","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>The triphosphate ester of tubercidin (tubercidin triphosphate, TuTP) was synthesized. This is an analog of ATP in which a CH group replaces the N-7 of the adenine ring. The rate of TuTP hydrolysis by myosin in the presence of Mg2+ was the same as that of ATP in the 10(-7)-10(-3) M range, whereas the increment in the optical density of myosin ihe 290mmu region caused by TuTP was twice that caused by ATP. TuTP is hydrolyzed by actomyosin faster than ATP, the value of Vmax being about 4 times larger while the Km values were of the same order of magnitude. The rate of superprecipitation induced by TuTP was 50% of that caused by ATP at nucleotide concentrations of 3-60 muM. A similar difference was observed with respect to the rate of tension development by glycerol-extracted rabbit psoas fibers upon addition of these two substances. Substitution of ADP by tubercidin diphosphate (TuDP) in F-actin did not affect the rate of superprecipitation or enzymic activity of actomyosin.</p>","PeriodicalId":76011,"journal":{"name":"Journal of mechanochemistry & cell motility","volume":"3 2","pages":"103-10"},"PeriodicalIF":0.0,"publicationDate":"1975-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"11393218","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Cinemicrographic analysis of the movement of flagellated bacteria. I. The ratio of the propulsive velocity to the frequency of bodily rotation.","authors":"T Yoshida,&nbsp;K Shimada,&nbsp;S Asakura","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>On the basis of the hydrodynamic model that the propulsion of flagellated bacteria in a fluid is a consequence of the propagation of helical waves along the length of flagella or flagellar bundles, it is predicted that propulsion must be accompanied by a rotation of bacterial body about the direction of translation (Chwang and Wu, 1971), and that propulsive velocity u is directly proportional to the frequency of bodily rotation fB, the proportional constant being a complicated function of various parameters describing the sizes and shapes of body and flagella. In this study we have measured not only u but also fB by cinemicrography or sometimes by dual cinemicrography, using a mono- trichously flagellated Pseudomonas strain and a multitrichously flagellated Salmonella strain, and calculated the ratio u/fB. Though the values of u/fB thus determined for a number of bacteria of each strain scattered in a wide range, average values of u/fB were likely to be independent of u, in support of the theoretical prediction. Moreover, in Pseudomonas as well as in Salmonella, it was found that the experimental values of u/fB were in semiquantitative agreement with theoretical values expected from the hydrodynamic model for appropriate values of the geometrical parameters. Taking into account these results, it was concluded that the validity of this model has been supported experimentally.</p>","PeriodicalId":76011,"journal":{"name":"Journal of mechanochemistry & cell motility","volume":"3 2","pages":"87-98"},"PeriodicalIF":0.0,"publicationDate":"1975-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"12390325","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Computer simulation of flagellar movement. III. Models incorporating cross-bridge kinetics.","authors":"C J Brokaw,&nbsp;D R Rintala","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>A computer simulation procedure is used to analyze the generation of propagated bending waves by flagellar models in which active sliding is generated by a cycle of cross-bridge activity. Two types of cross-bridge cycle have been examined in detail. In both cycles, cross-bridge attachment is followed immediately by a configurational change in the cross-bridge, which transfers energy to a stretched elastic element and generates a shearing force between the filaments. In the first model, which has cross-bridge behavior close to current ideas about cross-bridge behavior in muscle, cross-bridge attachment is proportional to curvature of the flagellum and detachment is an exponential decay process. The configurational change is equivalent to an angular deviation of pi/5 radians. In the second type of cross-bridge cycle, cross-bridge attachment occurs rapidly when a critical curvature is reached, and detachment occurs when a critical curvature in the opposite direction is reached. With this cycle, an unrealistically large angular deviation of the cross-bridges, equivalent to 3.0 radians, is required to obtain bending waves of normal amplitude. Both models generate bending wave patterns similar to those obtained in earlier work. However, the behavior of the second type of cross-bridge model more closely matches the actual behavior of flagella under experimental conditions: the chemical turnover rate per beat cycle remains constant as the viscosity is increased, and reduction in the number of active cross-bridges can cause a reduction in beat frequency, with little change in amplitude or wavelength.</p>","PeriodicalId":76011,"journal":{"name":"Journal of mechanochemistry & cell motility","volume":"3 2","pages":"77-86"},"PeriodicalIF":0.0,"publicationDate":"1975-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"12391767","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Very high tension with very little ATP breakdown by active skeletal muscle.","authors":"N A Curtin,&nbsp;R E Davies","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>The tension developed and the chemical change occurring during stretching at velocities up to 2l0 sec-1 and during isometric contraction of dinitrofluorobenzene-treated and untreated frog sartorius muscle have been measured. At all velocities of stretching the tension was greater than during shortening at the same velocity and the mean rate of chemical change was less than or equal to the rates found in similar studies of shortening. For velocities 0.18, 0.33 and 0.66l0 sec-1, the mean rate of chemical change was significantly less (P less than 0.05) than during shortening at the same velocity. At the highest velocity of stretching the tension at l0 was about 0.8 P0 and the mean rate of chemical change was about the same as that for isometric contraction. At low velocity (0.1 l0 sec-1) the tension was as high as 1.4 P0 and the mean rate of chemical change during the stretches at the three slowest velocities was significantly less (P less than 0.05) than during isometric contraction; the lowest mean rate of chemical change amounted to only about 25% of that for isometric contraction. The fact that the chemical change was so low suggests that during stretching crossbridges can form links and develop tension without breaking down ATP.</p>","PeriodicalId":76011,"journal":{"name":"Journal of mechanochemistry & cell motility","volume":"3 2","pages":"147-54"},"PeriodicalIF":0.0,"publicationDate":"1975-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"12262487","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Platelet contractile proteins: separation and characterization of the actin and myosin-like components.","authors":"D H Cove,&nbsp;N Crawford","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>Solution of thrombosthenin, the contractile protein complex isolated from pig platelets, have been studied by analytical ultracentrifugation and zone sedimentation in sucrose density gradients. Freshly prepared thrombosthenin in 0.6 M KCl shows a prominent peak in the ultracentrifuge with S degrees 20w about 5.5 and higher molecular weight aggregates (greater than 100S) sedimenting quickly to the bottom of the cell. Short term storage of high ionic strength solutions of thrombosthenin induces actomyosin-like gel formation and these gels dissociate with ATP and Mg2+ ions into two components of S degrees 20w 8.0 and S degrees 20w50. The supernatant, after actomyosin gel removal, contains only the S degrees 20w5.5 protein. From results of Ca2+ ATPase activity measurements and SDS polyacrylamide gel electrophoretic mobilities of dissociated thrombosthenin separated into fractions in sucrose density gradients, it is concluded that the S degrees20w5.5 protein species is the myosin-like protein of thrombosthenin. The S degrees 20w8.0 protein is not fibrinogen but also has myosin-like properties and is believed to be myosin dimer. Species of higher S values seen in the presence of ATP and Mg2+ in the analytical ultracentrifuge and located in the higher density zones of the sucrose gradients all gave in SDS polyacrylamide gel electrophoresis a single band of molecular weight 46-47,000 daltons. These subunit proteins appear to be derived from a range of polymeric variants of the F-actin-like protein of the contractile complex. All these higher density F-actin-like proteins readily form superprecipitates and display syneresis when combined with rabbit skeletal muscle myosin or platelet myosin. They are also all capable of conferring upon these two myosins a Mg2+ activated ATPase activity. It is suggested that in thrombosthenin solutions a myosin monomer-dimer equilibrium state exists which can be directionally influenced by a number of factors. The coexistence in the solution of F-actin and Mg2+ ATP, for example, increases the propensity of the myosin-like protein to form the higher molecular weight aggregate. Such aggregation may be the initiating mechanism for the intracellular organization of the thick filaments of the actomyosin complex, preparatory to a contractile event.</p>","PeriodicalId":76011,"journal":{"name":"Journal of mechanochemistry & cell motility","volume":"3 2","pages":"123-33"},"PeriodicalIF":0.0,"publicationDate":"1975-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"11348497","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Studies on the amino groups of myosin-ATPase. II. Localization of the amino groups.","authors":"A Muhlrad,&nbsp;A Afolayan","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>1-5 of the epsilon-amino groups of myosin were trinitrophenylated by 2,4,6-trinitrobenzene sulphonate. The Mg2+-activated ATPase activity was found to increase twenty fold while the K+-activated ATPase was strongly inhibited as a result of this treatment. Myosin was dissociated by urea after trinitrophenylation and its heavy and light chains were isolated. Virtually all the introduced trinitrophenyl groups were found in the heavy chain indicating that the lysyl residues, the modification of which affects the ATPase activity, are located at the heavy core of the myosin molecule.</p>","PeriodicalId":76011,"journal":{"name":"Journal of mechanochemistry & cell motility","volume":"3 2","pages":"99-101"},"PeriodicalIF":0.0,"publicationDate":"1975-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"11348498","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The identification and subcellular localization of thrombosthenin \"M\", the myosin-like component of pig platelets.","authors":"G L Harris,&nbsp;N Crawford","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>A protein has been studied which spontaneously precipitates from stored fractions of platelet soluble phase prepared by density gradient centrifugation. It is rich in a Ca2+ ATPase activity which displays an activity/pH profile resembling that of skeletal muscle myosin. Adjustment of freshly prepared soluble phase fractions to 0.6 M with respect to KCl and dilution 1 in 3 results in the precipitations of a protein fraction with essentially the same enzymatic properties as the spontaneously precipitable protein. These two similar proteins represent between 9 and 13% of the soluble phase total protein and each account for almost the whole of divalent cation activated ATPase activity of the soluble phases from which they were derived. The Mg2+ ATPase activity is only about twice purified with respect to the soluble phase enzyme activity, but the Ca2+ ATPase shows a 10-13-fold enrichment. Synthetic actomyosins can be prepared from the two proteins by addition of either platelet or skeletal muscle actin. These show significant increases in Mg2+ ATPase at the most favourable combination ratios. The ratio between the yield of soluble phase protein obtained by dilution precipitation and the lactate dehydrogenase activity of the soluble phase remains constant under a wide range of homogenization and sonication conditions applied to the original whole platelet suspensions. This confirms our earlier view that the soluble phase is a valid intracellular compartment for a considerable proportion of the platelet contractile protein and that in the complex the myosin-like component predominates.</p>","PeriodicalId":76011,"journal":{"name":"Journal of mechanochemistry & cell motility","volume":"3 2","pages":"135-45"},"PeriodicalIF":0.0,"publicationDate":"1975-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"11226819","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}