ISSN:
1750-3841
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
,
Process Engineering, Biotechnology, Nutrition Technology
Notes:
A study was made of the nucleosidetriphosphatase (NTPase) activities of myofibrils isolated from pre-rigor, rigor, and post-rigor bovine semitendinosus and psoas muscles with three different extracting solutions: 1) 0.25M sucrose, 1 mM ethylenediaminetetraacetic acid (EDTA), 0.05M trischydroxy-methyl)-aminomethane (Tris), pH 7.6; 2) 0.15M KCI, 1 mM EDTA, O.OSM Tris, pH 7.6; and 3) 50% glycerol, 1mM EDTA, 0.05M Tris, pH 7.6. Post-mortem storage was at 2 and 16°C. By 6 hr post-mortem, the Ca++- and Mg++-modified adenosine-triphosphatase (ATPase) activities at an ionic strength (I-/2) of 0.18 had increased 20–50% over the O-time level. An increase in Ca++-modified ATPase of Γ/2 = 0.52 was also found. The Mg++-modified inosinetriphosphatase (ITPase) at Γ/2 = 0.18 increased with post-mortem time, but the Cat+-modified ITPase at Γ/2 = 0.18 did not change.The Ca++-modified ITPase activity at Γ/2 = 0.52 increased for the first 24 hr post-mortem, but after 312 hr post-mortem, it had decreased back to the O-time level. No differences in NTPase activities were found between the semitendinosus and the psoas muscles or between post-mortem storage at 2 and 16°. Use of sucrose or KCI extracting solutions gave the most consistent NTPase results. The low Mg++-modified NTPase activity at Γ/2 = 0.52 suggests that it is possible to dissociate thick and thin filaments from rigor muscle through the use of 5mM ATP or ITP. The fact that NTPase activities in the presence of certain modifiers did not change with post-mortem time suggests that the increased NTPase activities did not result from a proteolytic loss of part of the enzyme molecule, causing an increased activity per unit of protein. Mg++-modified ATPase activities in the presence of a Ca++ chelator indicated that tropomyosin, the most sensitive of the three myofibrillar proteins to proteolytic degradation, had not undergone significant proteolysis, even after 312 hr post-mortem.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1365-2621.1967.tb01322_32_3.x
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