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  • 1
    ISSN: 1520-4995
    Quelle: ACS Legacy Archives
    Thema: Biologie , Chemie und Pharmazie
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    ISSN: 1520-4995
    Quelle: ACS Legacy Archives
    Thema: Biologie , Chemie und Pharmazie
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    ISSN: 1750-3841
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: 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.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    Journal of food biochemistry 7 (1983), S. 0 
    ISSN: 1745-4514
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Current evidence indicates that, of the thirteen known lysosomal peptide hydrolases, only seven, cathepsins A, B, C, D, H, L, and lysosomal carboxypeptidase B are located inside skeletal muscle cells. Only one of the reported neutral and alkaline proteases is located inside skeletal muscle cells', this neutral protease is the Ca2+-dependent proteinase, CAF. With the possible exception of cathepsin N, which can degrade collagen, it seems probable that any protease that contributes to postmortem tenderization needs to be located inside muscle cells. Because very little degradation of myosin or actin occurs in postmortem muscle, most of the small amount of proteolytic degradation of the myofibrillar proteins that occurs during postmortem storage must be due to CAF, which is unique in being unable to degrade myosin and actin. It is not certain that postmortem proteolysis by CAF causes increased tenderness; some recently discovered actin-fragmenting proteins could be involved.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    Journal of food science 48 (1983), S. 0 
    ISSN: 1750-3841
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The accuracy and precision with which Ca++-dependent proteinase (CAF) activity can be assayed in skeletal muscle tissue was determined by using two experimental approaches: (1) repeated sampling of a homogeneous batch of minced rat skeletal muscle to estimate variation among CAF assays done on fractions made from the same muscle tissue and to ascertain the effect of sample size on assays of CAF activity; and (2) comparison of CAF assays done on muscle samples of similar weights obtained from different animals that had been treated alike. Muscle CAF activity can easily be detected in 0.5g muscle samples, but the measured activity is not accurate and increases with increasing sample size. The decreased CAF activity assayed in small muscle samples seemed to originate from failure to extract all the CAF in these samples, possibly because of the different homogenizer that must be used to homogenize small samples. If a Waring Blendor is used at 8000 rpm, muscle samples must be 19g or larger to obtain accurate assays of CAF activity. The coefficient of variation for duplicate assays of CAF activity on the same P045 crude CAF fraction was 5.85% (assay variation); for assays of CAF activity on different samples of the same muscle tissue, 7.18% (sampling variation and variation in procedure for preparing crude CAF fractions); and for assays of CAF activity on muscle tissue obtained from the different groups of animals that had been treated alike, 10.30% (animal variation). Hence, CAF activity can be measured with acceptable precision in skeletal muscle tissue, but treatments designed to alter muscle CAF activity must cause changes of at least 20% to be detectable against the natural variation of muscle CAF activity in different animals.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 6
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    Journal of food science 35 (1970), S. 0 
    ISSN: 1750-3841
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: SUMMARY– Effects of postmortem storage of rabbit muscle at 25° on the properties of α-actinin and tropomyosin-troponin-containing fractions prepared from this muscle were studied. Postmortem storage did not affect the amount of α-actinin or tropomyosin-troponin that could be extracted from rabbit myofibrils by water washes or by a 3-day, pH 8.5, low-ionic strength extraction. Myosin B prepared from postmortem muscle underwent turbidity development much faster than myosin B prepared from muscle immediately after death. This increased rate of turbidity development was probably not due to postmortem changes in α-actinin, since the ability of α-actinin to accelerate the ATPase (for abbreviations used in this paper, see list under References) activity or the turbidity response of reconstituted actomyosin suspensions gradually decreased, rather than increased, during postmortem storage. However, even after 14 days postmortem at 25°α-actinin retained some activity in both the ATPase and turbidity tests. Moreover, the increased rate of turbidity development of postmortem myosin B was probably not due to degradation of the tropomyosin-troponin complex, since postmortem storage affected the activity of this complex only slightly and, even after 14 days post-mortem, the tropomyosin-troponin complex still conferred some Ca++-sensitivity on reconstituted actomyosin suspensions. Myosin B prepared from postmortem muscle did not contain more active α-actinin than myosin B prepared from muscle immediately after death, but the F-actin-tropomyosin-troponin interaction was gradually weakened during postmortem storage without any evident degradation of F-actin and the tropomyosin-troponin complex themselves. The weakened F-actin-tropomyosin-troponin interaction probably caused loss of Ca++-sensitivity in myosin B prepared from postmortem muscle. Results of this study indicate that postmortem changes in α-actinin and the tropomyosin-troponin complex per se are not the primary cause of postmortem modification in the actin-myosin interaction.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 7
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    Journal of food science 35 (1970), S. 0 
    ISSN: 1750-3841
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: SUMMARY– A study was done on the effects of in vitro storage of purified α-actinin, troponin, tropomyosin, and the tropomyosin-troponin complex on the activity of these protein fractions in the ATPase and superprecipitation assays. Storage was done at various combinations of temperatures between 0 and 40°C and pH values between 5.7 and 7.0. Even after 40 hr of storage, activities of purified tropomyosin and the tropomyosin-troponin complex were not affected by any combination of temperature and pH included in this study, but activities of purified α-actinin and troponin were almost completely lost after 16 hr at 40°C and pH 5.7. Storage for 40 hr at low pH (5.7) and low temperatures (0°C) did not affect the activity of either α-actinin or troponin, but 40 hr of storage at high temperatures (40°C) and neutral pH caused some loss in activity for both these proteins. This loss of activity caused by 40°C, pH 7.0 storage was much more noticeable in the case of troponin than in the case of α-actinin. Storage periods of 40 hr or longer were required before any loss of α-actinin activity could be detected at pH 7.0 and 40°C. Since most meat animal carcasses are chilled soon after exsanguination and attain muscle temperatures of 25°C or lower before the pH falls below 6.2, it is probable that α-actinin and tropomyosin-troponin activity remain almost unchanged in meat handled through normal market channels. However, myofibrillar tissue in those porcine animals whose musculature undergoes a very rapid post-mortem decline in pH so that values of 5.7 or less are reached while muscle temperatures are still 37°C or higher may lose much of its α-actinin and tropomyosin-troponin activity during the first 24 hr post-mortem.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 8
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    Journal of food science 32 (1967), S. 0 
    ISSN: 1750-3841
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: 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.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 9
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    Journal of food science 29 (1964), S. 0 
    ISSN: 1750-3841
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Post-mortem changes in tenderness and protein solubility were studied in bovine semitendinosus muscles. Muscles excised immediately post-mortem were compared with muscles left attached to the skeleton. Post-mortem times of 0, 6, 12, 24, 72, and 312 hr were studied. Sarcoplasmic protein solubility was highest immediately after slaughter and lowest in muscles left attached to the skeleton. Myofibrillar protein solubility was decreased in muscles left attached. Protein solubility changed during the first 6 hr post-mortem but not during the 6- to 312-hr aging period. Muscles left attached to the skeleton were least tender immediately after death and gradually increased in tenderness during post-mortem aging. Excised muscles were least tender 6–12 hr post-mortem and became progressively more tender thereafter. Even after 312 hr of aging, excised muscles were less tender than muscles still attached to the skeleton. Protein solubility did not appear to be related to tenderness. Possible relationships of muscle contraction to tenderness were discussed.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 10
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    Journal of food science 29 (1964), S. 0 
    ISSN: 1750-3841
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Age-associated structural changes in collagenous residues isolated from the loose connective-tissue network found within bovine biceps femoris muscle were studied with collagenase used as a structural probe. Rate of enzymatic digestion was measured by following the release of soluble protein, hydroxyproline, and ninhydrin-positive material into the medium surrounding the fibrous residues. Under the conditions of the experiment, 8–11% of the protein and 8–21% of the hydroxyproline in the residues were solubilized after 12 hr of incubation with collagenase. Samples from four age groups were studied: Group I, veal, 40–49 days old; Group II, steers, 403–495 days old; Group III, cows, 4 years, 8 months to 5 years, 5 months old; Group IV, aged cows, 10 years, 2 months and 10 years, 5 months old. The groups ranked I, III, IV, and II, from fastest to slowest, in rate of hydrolysis by collagenase. However, it was postulated that the larger amounts of lipid associated with the Group II samples acted to shield collagenase-labile bonds and cause a slow rate of hydrolysis. Making this assumption, it appears that susceptibility to collagenase digestion of loose connective tissue follows an age pattern similar to that reported for skin and tendon collagen.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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