Myofibrillar proteins extraction

The binding of sarcoplasmic and myofibrillar proteins extracted from post-rigor pork muscle, and from 7- and 12-months dry-cured hams with volatile compounds such as 3-methyl-butanal, 2-methyl-butanal, 2-pentanone, hexanal, methional and... 

Modification of fish proteins by proteolytic enzymes to increase their solubilities illustrates a variety of techniques and approaches. Basically, three general enzymic methods have been used to prepare fish proteins or hydrolysates with altered solubilities and other functionalities. These methods include (a) the enzymic solubilization of fish protein concentrate prepared by hot solvent extraction of fish, (b) the enzymic modification of myofibrillar proteins extracted from fish with 0.6M NaCl, and (c) the proteolysis of whole fish to prepare biological fish protein concentrate (FPC). 

CE has also been successfully apphed to the study of muscle proteins, and some of these applications have been recently reviewed. - - Methods for the determination of muscle proteins were based on CZE, SDS-CE, or isoelectric focusing (CEIF). Meat species identification was carried out by analyzing sarcoplasmic or myofibrillar proteins by a replaceable polymer-filled SDS-CE method (Table 30.8). However, the analysis of sarcoplasmic protein profiles allowed better differentiation among beef, pork, and turkey meat (Figure 30.8). The importance of sample preparation in the established method was highlighted since sarcoplasmic proteins extracted by simply homogenizing meat with cold bidistilled water were most useful for meat species identification when protein profiles were examined by linear discriminant analysis. On the other hand, myofibrillar proteins extracted with 0.6 M NaCl/0.01 M phosphate buffer with 0.5% polyphosphates (pH 6.0) were not useful for raw meat species identification, although they may be of importance in the identification of heat-processed meats. ... 

The myofibrillar proteins make up 50-60% of the total protein of muscle cells. Insoluble at low ionic strengths, these proteins dissolve when the ionic strength exceeds -0.3 and can be extracted with salt solutions. Analysis of isolated mammalian myofibrils86 shows that nine proteins account for 96% or more of the protein myosin, which constitutes the bulk of the thick filaments, accounts for 43% and actin, the principal component of the thin filaments, 22%. 

Before selecting a method to measure a specific aspect of protein functionality, one must decide on the complexity of the testing matrix. Researchers have used a single purified protein, a crude extract of proteins, a prototype food product, or an actual product to study protein functionality. For meat studies, formulated meat systems, ground muscle, myofibrillar proteins, salt-soluble proteins, actomyosin,... 

Among the above hypotheses, effects of lipids (4-17,59-62, 69-71,155-159), formaldehyde (160-166), and gas-solid interface TMJ appear to be very important in Gadoid fishes. Denaturation of myofibrillar proteins caused by free fatty acids and/or lipid peroxides must occur during frozen storage. To prove this, Jarenback and Liljemark have shown by electron microscopy that, in muscle stored frozen with added linoleic and linolenic hydroperoxides, myosin became resistant to extraction with salt solution (168). 

Power ultrasound has also been found to be effective in the extraction of protein from meat [58]. Ultrasound disrupts the meat myofibrils and this releases a sticky exudate which binds the meat together. The binding strength, water holding capacity, product color, and yields were examined after treatment either with salt tumbling, sonication, or both. Samples which received both salt treatment and sonication were superior in all qualities. Similar results were obtained from a study of the effect of sonication on cured rolled ham [59]. Ultrasonic treatment enhanced the extraction of myofibrillar proteins leading to an increase in the strength of the reformed meat. 

Much research has been devoted to working out optimum parameters of producing different protein concentrates from fish and krill (Lanier, 1994). While the products have high nutritional value and many are tasteless and odorless, some, manufactured in denaturing conditions, lack the desired functional properties. A good example is the fish protein concentrate obtained by hot azeotropic isopropanol extraction. On the other hand, a concentrate of myofibrillar proteins known as surimi, produced mainly from fish and to a lesser extent from poultry and meat, is highly functional. 

Electron Microscopy. Examination of fish proteins by electron microscopy conclusively shows that actomyosin aggregates during frozen storage (59,63,69). The change in structures of the extracted myofibrillar proteins and of the myofibril residues of frozen-stored cod muscle was studied by electron microscopy. The decrease in the number of actomyosin filaments and an increase in the number and size of large aggregate were found (69). Unfrozen carp actomyosin, either dissolved in 0.6M KC1 or suspended in 0.05M KC1, exists in a typical arrowhead... 

Effects of linoleic acid and linoleic acid hydroperoxides on the myofibrils and the solutions of myofibrillar proteins of cod muscle have been proved using the electron microscopy (80). Linoleic acid hydroperoxides were ten times more effective than linoleic acid in reducing the amount of the protein in KCl-extracts from the myofibrils incubated with the acid or its hydroperoxides. Linoleic acid seemed to prevent the dissolution of the myofibril frame work but appeared not to impair the extraction of myosin while hydroperoxides appeared to cause a retention of A-bands (myosin) in the myofibrils. 

The myofibrillar proteins of fish are those proteins soluble in 0.6M NaCl (14). These proteins have been modified with Rhozyme P-11 at an enzyme-to-protein ratio of 1 75 at 30 °C, pH 6.6 for 1 hr. The modified myofibrillar protein was quantitatively recovered as a hexametaphosphate complex at pH 3. Residual lipids were removed by solvent extraction of the complex. After a solution of the phosphate-protein complex was neutralized to pH 7, it was spray-dried or freeze-dried to yield a freely soluble product which was 93.5% protein, 0.15% lipid, and 1.4% phosphate. 

Meat, sarcoplasmic proteins extracted in bidistilled deionized water, myofibrillar extracted in 0.6 M NaCl/0.01 M phosphate buffer, 0.5% polyphosphates, pH 6.0, Biorad SDS sample buffer Meat adulterated with chicken egg white... 

Much work has been reported on dried and whole fish. Tg s in frozen fish such as cod, tuna, mackerel, sea bream and bonita have been determined using DSC [98 ]. This work is normally carried out with a view to determining the safe storage conditions for these products. Both dried fish muscle and extracted protein fractions showed glass transitions. The 2 s of muscle and myofibrillar proteins from red-muscle fish tended to be lower than those from white-muscle fish. There was no difference in the Tg of sarcoplasmic reticulum. The myofibrillar proteins are responsible for the contractile mechanisms in muscle. These are predominantly... 

Methods for cell and sub-cellular fractionation include immuno-isolation, electromigration e.g. free flow electrophoresis), flow cytometiy, density gradient isolation of organelles and sequential extraction. The use of some of these approaches to investigate the mitochondrial and myofibrillar sub-proteomes of the heart will be described in Sections 3.4 and 3.6 respectively. A particular problem in proteomic analysis of the heart is the diversity of cell types that are present. Proteomic profiles of total myocardial lysates are dominated by the proteins present in cardiac myocytes, but such samples... 

Muscle proteins are an important component of meat and can be classified according to solubility as sarcoplasmic (water soluble), myofibrillar (salt soluble), or stromal (insoluble) proteins. The application of CE to the analysis of meat proteins has been predominantly for separation of sarcoplasmic proteins in aqueous extracts from fish, bovine, and chicken muscle. The sarcoplasmic proteins that are present are mainly metabolic enzymes and therefore their separation profiles are useful for the purpose of species identification. Some reports also exist of the simultaneous separation of sarcoplasmic and myofibrillar meat proteins using SDS-CGE. 

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