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  • Blackwell Publishing Ltd  (8)
  • 1965-1969  (8)
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  • 1
    Electronic Resource
    Electronic Resource
    Molecular Properties of Post-Mortem Muscle. (1967)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of food science 32 (1967), S. 0 
    Details
    ISSN: 1750-3841
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Notes: SUMMARY— Post-mortem changes in nucleoside triphosphatase activity of bovine myosin B have been studied by using several different modifiers with either 5 mM ATP or 5 mM ITP as substrate at ionic strengths (r/2) of 0.09, 0.19, or 0.52. Enzymic activity was determined by measuring the release of inorganic phosphate. There was very little difference in enzymic activity between myosin B isolated from prerigor, rigor (24 hr post-mortem) or post-rigor (312 hr post-mortem) muscle stored at either 2° or 16°C except that the specific activity of myosin B prepared from muscle stored for 12–24, hr post-mortem was higher than activity of myosin B prepared immediately after death. This increase cannot be explained in terms of rigor shortening, but suggests that a change in myosin conformation or in the nature of the actin-myosin interaction occurs in post-mortem muscle. If an actin-myosin interaction occurs during rigor mortis and if this association remains unchanged during extraction of myosin B, then the very low Mg++-modified myosin B enzymic activities obtained at Γ/2 = 0.19 and 0.52 indicate that this interaction is not irreversible. Extraction in the absence of ATP produced a myosin B whose ATPase activity was markedly inhibited by trace amounts of Mg++. This may be due to the absence of a-actinin in these myosin B preparations. No consistent differences in activation energies were found either at Γ/2 = 0.19 or 0.52 among the NTPase reactions of myosin B samples prepared from muscle after various times of post-mortem storage.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2621.1967.tb00828.x
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  • 2
    Electronic Resource
    Electronic Resource
    Isometric Tension Changes and Shortening in Muscle Strips During Post-mortem Aging (1967)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of food science 32 (1967), S. 0 
    Details
    ISSN: 1750-3841
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Post-mortem tension changes of rabbit psoas and beef geniohyoideus and semitendinosus muscle were studied. A special device was constructed and used to measure these changes while holding the muscle isometrically. It has been possible to demonstrate a pattern of tension development and cessation in rabbit muscle at 24°C and in beef muscle at 0°, 10°, and 24°C. With rabbit muscle no tension development was detected at 0° or 10°C. Initiation of tension development is affected by the ante-mortem state of the animal as well as by temperature. The post-mortem tension decline occurs after the disappearence of ATP and evidently is not related to ATP degradation. Possible relationships between post-mortem tension changes and meat tenderness are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2621.1967.tb01283.x
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  • 3
    Electronic Resource
    Electronic Resource
    Molecular Properties of Post-Mortem Muscle. 4. Effect of Temperature on Adenosine Triphosphate Degradation, Isometric Tension Parameters, and Shear Resistance of Bovine Muscle (1967)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of food science 32 (1967), S. 0 
    Details
    ISSN: 1750-3841
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Notes: SUMMARY– Investigations were conducted on the effect of three storage temperatures, 2°, 16°, and 37°, on the changes and relationships of certain chemical and physical properties of post-mortem bovine semitendinosus and psoas muscle. Post-mortem muscle shortening was measured with the isometer. Isometric tension development was maximal at 2°, minimal at 16°, and at 37° tension was approximately one-half that developed at 2°. The large tension development at 2° very likely originates from the same events as those in “cold shortening.” Differences in isometric tension parameters were noted between muscles in that psoas muscle developed tension and lost the ability to maintain tension more quickly than did the semitendinosus. Loss of ability to maintain tension was observed only at 2°, and this could correspond to a “resolution” of rigor mortis. Adenosine triphosphate (ATP) degradation was measured by two methods, ammonia production and bioluminescent enzymic method; the bioluminescent method proved to be the more satisfactory. A common relationship was observed between pH and ATP for both muscles and the three temperatures studied. No direct relationship was found between ATP degradation and shear resistance with the possible exception of muscle stored at 37°. Isometric tension parameters and shear resistance were related somewhat at 2° in semitendinosus muscle, but no relationship existed at 16° and 37°. Although considerable tension developed in psoas and semitendinosus muscle at 37°, shear resistance values decreased continuously, indicating that factors other than shortening are more important at high temperature and that these factors are temperature-dependent.The role of ATP degradation in tension development was difficult to interpret, since at 2°, only a small change occurred in ATP level during large tension development, and the level of ATP at 2° did not differ from ATP level in muscle stored at 16° which developed little tension.Differences in post-mortem muscle shortening at 2 and 37 are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2621.1967.tb09692.x
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  • 4
    Electronic Resource
    Electronic Resource
    Molecular Properties of Post-Mortem Muscle. 3. Electron Microscopy of Myofibrils (1967)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of food science 32 (1967), S. 0 
    Details
    ISSN: 1750-3841
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Notes: SUMMARY— A study was made of the fine structure of myofibril suspensions prepared from seven heifers immediately after death and after various times post-mortem. Studies on myofibrils sampled immediately after death showed that sucrose isolation gave the best structural preservation as indicated by maintenance of Z-line structure. Although the appearance of resting muscle was maintained in both sucrose and KCI preparations, several myofibrils from the KCI-treated preparations showed stretched sarcomeres. Glycerol-treated myofibrils usually had shorter sarcomere lengths than myofibrils prepared with the other two solvents. Although fibrillar preservation seemed adequate when glycerol was used, Z-line structure was seldom well-preserved with glycerol.Myofibrils from muscle sampled 24 hr post-mortem at 2°C were supercontracted with thick filaments pushed against or through the Z-line, and no trace of l-bands remained. Myofibrils from muscle sampled 24 hr post-mortem at 16°C were contracted, but to a much lesser extent than 2°C-24 hr myofibrils. Storage at 2°C for 312 hr after death resulted in myofibrils that were contracted and that were structurally in a much poorer state of preservation than their 16°C counterparts. The 16°C-312 hr myofibrils were slightly contracted as indicated by the absence of H-zones and the presence of prominent, although narrowed, I-bands. All observations showed that shortening accompanying rigor mortis caused changes in banding patterns similar, and probably identical, to those predicted by Huxley's sliding filament model for contracting muscle.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2621.1967.tb09691.x
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  • 5
    Electronic Resource
    Electronic Resource
    Molecular Properties of Post-Mortem Muscle. 7. Changes in Nonprotein Nitrogen and Free Amino Acids of Bovine Muscle (1969)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of food science 34 (1969), S. 0 
    Details
    ISSN: 1750-3841
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Notes: SUMMARY– Proteolysis and its relationship to tenderness were studied by measuring nonprotein nitrogen (NPN), free amino groups, and shear resistance during post-mortem aging of bovine muscle. Both NPN and free amino groups increased during post-mortem aging, indicating some degradation of proteins and/or peptides. However, neither the increase in NPN nor free amino groups was related to post-mortem tenderization since these quantities increased only after most of the improvement in tenderness had occurred. Much of the increase in NPN or free amino groups may originate from degradation of sarcoplasmic proteins or peptides. It is suggested that weakening or breaks at crucial points in the sarcomere, such as at the junction of the Z-line with the thin filaments, occur within the first 48-72 hr post-mortem and that this weakening or cleavage is responsible for tenderization. Cathepsin D may be responsible for this weakening but most of the available evidence is against proteolysis as the primary cause of post-mortem tenderization.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2621.1969.tb00918.x
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  • 6
    Electronic Resource
    Electronic Resource
    Molecular Properties of Post-Mortem Muscle. 6. Effect of Temperature on Protein Solubility of Rabbit and Bovine Muscle (1969)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of food science 34 (1969), S. 0 
    Details
    ISSN: 1750-3841
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Notes: SUMMARY– Studies were conducted to investigate the effect of temperature on the actin-myosin interaction of rabbit and bovine muscle during rigor and post-rigor shortening. Muscle was stored at four different temperatures (2°, 16°, 25° and 37°), corresponding to three types of post-mortem muscle shortening: cold, minimal and high temperature. These three types of shortening are presumably related to different states of the actin-myosin interaction in post-mortem muscle. Post-mortem tenderization may be the result of either actin-myosin dissociation or F-actin depolymerization.To detect the occurrence of either of these possible changes, two salt solutions, differing widely in their myofibrillar protein extracting abilities, were used to compare post-mortem myofibrillar protein solubility after different times of post-mortem storage and to provide information about the actin-myosin complex. Myofibrillar protein solubility of both rabbit and beef muscle in 0.5M KCl, 0.1M phosphate, pH 7.4, increased markedly with increasing post-mortem storage at temperatures up to 25deg;. Similar solubility changes were obtained with 1.1M Kl, 0.1M K phosphate, pH 7.4, but these changes were much smaller in magnitude. Solubility in both salt solutions, in general, decreased for muscle stored at 37°.Although time and temperature of post-mortem storage caused appreciable alterations in protein solubility, these alterations could not be directly related to changes in tenderness or sarcomere length or to species differences in the effects of temperature on post-mortem shortening. Viscosity, analytical ultracentrifugation, and ATPase assays all indicated the absence of “normal” actomyosin in all myofibrillar protein extracts in this study. It was suggested that the 1.1 M KI extracts contained G-actomyosin, but the available evidence indicated the presence of only myosin in 3-hr, 0.5 M KCI extracts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2621.1969.tb00915.x
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  • 7
    Electronic Resource
    Electronic Resource
    Molecular Properties of Post-Mortem Muscle. I. Myofibrillar Nucleosidetriphosphatase Activity of Bovine Muscle (1967)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of food science 32 (1967), S. 0 
    Details
    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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  • 8
    Electronic Resource
    Electronic Resource
    Molecular Properties of Post-Mortem Muscle. II. Phase Microscopy of Myofibrils from Bovine Muscle (1967)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of food science 32 (1967), S. 0 
    Details
    ISSN: 1750-3841
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The structural appearance of homogenized myofibril suspensions from seven heifers was studied using phase microscopy at various times post-mortem with three different extracting solutions: 1) 0.25M sucrose, 1mM ethylenedi-aminetetraacetic acid (EDTA), 0.05M Tris-(hydroxymethyl) aminomethane (Tris), pH 7.6; 2) 0.15M KCI, 1mM EDTA, 0.05M Tris, pH 7.6; and 3) 50% glycerol, 1miZl EDTA, 0.05M Tris, pH 7.6. Samples were examined at death and 24 hr and 312 hr post-mortem with storage at 2 and 16°C. The 16°-24-hr samples exhibited a marked thickening of the A-band, a shortening of the l-band, and a replacement of the H-zone by a dark line or band. The 2°.24-hr samples showed only alternating light and dark bands of nearly equal width, which has been described as a typical supercontracted pattern. At 312 hr, more variability in banding pattern and fragmentation is encountered, but the trend is to preserve the pattern observed in the 24.hr samples. Occasionally, a narrow H-zone is seen in the center of a thickened A-band in the glycerol preparations sampled 312 hr post-mortem. The results suggest that cold shortening of bovine muscle is structurally identical to contraction and substantiate the view that shortening is minimal at 16° storage temperatures.The sucrose extracting solution consistently gave the best preservation and was used for subsequent experiments. Although banding patterns at death and in the 24-hr samples obtained with glycerol showed reliable consistency, these preparations at times exhibited a disturbing fuzziness. Results with KCI solutions were least desirable, because of repeatedly poor structural preservation, as indicated by variability in sarcomere lengths within and between fibers, as well as lack of clarity in banding.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2621.1967.tb01323_32_3.x
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