Myosin and adenosinetriphosphatase

Abstract

The major protein component of muscular tissue, myosin, has occupied the attention of many investigators because of its extreme importance as the contractile element of living. muscle. When isolated from the tissue it has many of the properties of the globulins, but its extreme molecular asymmetry gives rise to interesting properties which on the whole are anomalous to the corpuscular proteins. Past research has been devoted mainly to physico-chemical studies, and amongst these the investigation of double refraction of flow [Muralt & Edsall, 1930; Edsall & Mehl, 1940] and the interpretation of structure by X-ray methods [e.g. Boehm, 1931; 1933; Astbury & Dickinson, 1940] are perhaps most important. Some work has also been carried out upon its solubillty [Bate Smith, 1934], its chemical composition [Sharp, 1939; Bailey, 1937], upon the comparative biochemistry If future research confirms this view, it must be conceded that the original work of Liubimova & Engelhardt is a most fundamental contribution to muscle biochemistry. (121) K. BAILEY EXPERIMENTAL Preparation and properties of myosin Preparation of various myosins. The tissues used were the hind-leg and longissimus dorsi muscles of the rabbit, the pectoral muscle of chicken, the leg muscle,of the horse, the hind-leg muscle of the toad and frog, and the trimmed heart muscle of the pig and rabbit. The rabbits and chickens were killed by stunning and bled via the inferior vena cava; frogs and toads were pithed after leaving the animals in the cold room at 00. The muscle of those animals killed in the laboratory could be excised and minced within 10 min. after death, but material from the slaughterhouse was usually obtained about an hour after killing. In one instance, however, a sample of horse muscle was acquired within 15 min. after bleeding. Immediately after mincing, the tissue was added to 5 vol. of ice-cold salt solution containing KCI (0.5 M) and NaHCO3 (0.03 N). This extractant has been adopted by Greenstein & Edsall [1940] in an improved method for the preparation of myosin. Solid NaHCO3 was now added at intervals to maintain the pH at 7-7 5, and after stirring slowly for an hour at 00, the stroma was centrifuged down. The opalescent extract was filtered clear through a 2 in. layer of paper pulp (saturated with extractant) and diluted with 20 vol. of ice-cold water. Dilute HCI was now added to adjust the pH of the medium to 6-8-7-0, and after settling, the supernatant liquor was decanted and the myosin centrifuged down. For purification it was redissolved by the addition of solid KCI to a molarity of 0 5 and sufficient NaHCO3 to maintain the pH at 7. Without such addition, the myosin tends to become increasingly acid as purification proceeds, and although it remains soluble in salt, its enzymic activity diminishes, not by loss of an enzyme component, but by inactivation. After 3-4 precipitations and a final filtration through pulp, the protein may be stored in 0 5 M KCI at pH 7 and 00, in presence of a trace of toluene. N and P contents of rabbit myosin...

The Action of Ninhydrin on the Enzymatic and Actincombining Properties of Myosin

“…For some enzyme tests actomyosin, thrice precipitated by the method of Bailey (1942), was used. Glass-distilled water only was used in all enzyme preparations.…”

“…Nitrogen was determined by nesslerization after sulphuric acid digestion, using the reagent of Vanselow (1940). Weight of protein was calculated from the nitrogen estimations by using Bailey's (1942) figure for the nitrogen content of myosin, and Straub's (1943) figure for the nitrogen content of actin.…”

Investigations on the Mitochondria of the House Fly, Musca Domestica L

“…and Potter, and Swanson, reported activation by Ca ++ in liver homogenates, although this activation was not so great as with Mg ++. In contrast, the specific activation of ATPase from skeletal muscle by Ca ++ is well known (Bailey, 1942).…”

Dephosphorylation of Adenosinetriphosphate by Normal and Pathological Human Sera 1

“…The existence of a fairly specific ATP-ase active at alkaline pH is well established for muscle (6,21). Purified myosin does not act upon inorganic pyrophosphate or monophosphates (6), but splits ATP, inosine triphosphate (22), and to some extent inorganic triphosphate (23).…”