Muscle extractives

Since 673 kcal/mole could be released by complete oxidation, we might wonder why the yeast cells (and muscle) extract only 20 kcal/mole and leave so much of the potentially available energy untouched. This extra energy is there in ethanol and lactic acid and could be released if these compounds were oxidized further to C02. 

Fish muscles Extraction with Mcllvaine buffer pH QL = 0.04 pg/g Recovery = 33-35% [78]... 

The above observations suggested that hexoses arise in Nature by reaction of glycerose with dihydroxyacetone. A vast amount of practical information has been derived from investigation of plant- and muscle-extracts, two dissimilar systems that show many similarities in their biosynthetic manipulations. There is a close parallelism in the sequence of intermediates involved in the processes wherein D-glucose is converted to ethanol and carbon dioxide by yeasts, and to lactic acid by muscle during contraction. The importance of these schemes lies in their reversibility, which provides a means of biosynthesis from small molecules. 

Hexose diphosphate was found by Harden and Young69 in cell-free alcoholic-fermentation liquors. In 1930, it was observed that addition of fluoride to fermenting-yeast extracts leads to an accumulation of 0-phospho-D-glyceronic acid,60 which is also a metabolite of muscle extracts.61 Attention was turned, therefore, to the pathway from hexose diphosphate to 0-phos-pho-D-glyceronic acid. In 1932, Fischer and Baer62 described the synthesis of D-glycerose 3-phosphate, and, in 1933, Smythe and Gerischer63 noted... 

Lohmann118 detected an enzyme in muscle extracts, found later in plants and yeasts,104Co) 117,118 termed phosphoglucoisomerase, (optimum pH 9), which catalyzes the interconversion of D-glucose 6-phosphate (XVI) and D-fructose 6-phosphate (XVII). At equilibrium, which is attained rapidly, there is about 70 % of the former and 30 % of the latter. In a similar conver-... 

Fig. 3.20. HPLC-vis chromatograms, (a) Mixed standard 10 pg/kg equivalent (b) blank trout muscle extract, and (c) trout muscle spiked at /rg/kg. Peak heights in mV. Detection wavelength 618 nm. Peak identification MG = malachite green CV = crystal violet LMG = leucomalachit green LCV = leucocrystal violet. Reprinted with permission from J. A. Tarbin et al. [101].

Methyl glyoxal was finally removed from the glycolytic pathway after Lohmann showed (1932) that dialysed muscle extracts, supplemented with Pj, ATP, NAD+, etc., converted glycogen to lactic acid. If glutathione was not present to reactivate glyoxalase, methyl glyoxal did not form lactic acid. 

Barsby RW, Saian U, Knight DW, Houit JR. (1993). Feverfew and vascular smooth muscle extracts from fresh and dried piants show opposing pharmacoiogical profiles, dependent upon sesquiterpene iactone content. Planta Med. 59(1) 20-25. 

Sandee B., Schipper C.A. and Eertman R.H. (1996). High-performance liquid chromatographic determination of the imino acids (opines) meso-alanopine and D-strombine in muscle extract of invertebrates. J Chromatogr B Biomed Appl. ll 685 (l) 176-80. 

Neomycin residues were also found to be quite stable in chicken muscle extracts heated at 100 C for 5 h (9, 10). Unlike chicken muscle extracts, milk favored the loss of the contained neomycin when heated under similar conditions no more than 0-25% of the original activity could be determined after heating at 100 C for 5 h (9, 10). 

In 1929, Fiske and Subbarow,d/f h curious about the occurrence of purine compounds in muscle extracts, discovered and characterized ATP. It was soon shown (largely through the work of Lundsgaard and Lohman)f that hydrolysis of ATP provided energy for muscular contraction. At about the same time, it was learned that synthesis of ATP accompanied glycolysis. That ATP could also be formed as a result of electron transport became clear following an observation of Engelhardth i in 1930, that methylene blue stimulated ATP synthesis by tissues. 

Figure B3.1.1 A 15% SDS-polyacrylamide gel stained with Coomassie brilliant blue. Protein samples were assayed for the purification of a proteinase, cathepsin L, from fish muscle according to the method of Seymour et al. (1994). Lane 1, purified cathepsin L after butyl-Sepharose chromatography. Lane 2, cathepsin L complex with a cystatin-like proteinase inhibitor after butyl-Sepharose chromatography. Lane 3, sarcoplasmic fish muscle extract after heat treatment and ammonium sulfate precipitation. Lane 4, sarcoplasmic fish muscle extract. Lanes M, low-molecular-weight standards aprotinin (Mr 6,500), a-lactalbumin (Mr 14,200), trypsin inhibitor (Mr 20,000), trypsinogen (Mr 24,000), carbonic anhydrase (Mr 29,000), gylceraldehyde-3-phosphate dehydrogenase (Mr 36,000), ovalbumin (Mr 45,000), and albumin (Mr 66,000) in order shown from bottom of gel. Lane 1 contains 4 pg protein lanes 2 to 4 each contain 7 pg protein.

Nucleotidase present in 48,000 X Q supernatant fractions of rat and guinea pig skeletal muscle extracts has been examined briefly (7-4). 5 -UMP seems to be the preferred substrate. The enzyme from fish skeletal muscle has also been studied (75). This enzyme hydrolyzes all ribo-and deoxyribonucleoside 5 -phosphates (except dCMP and dTMP) with preference for 5 -IMP and 5 -UMP. The enzyme is strongly activated by Mn2+ Mg2+ is a less powerful activator, and Zn2+ and EDTA are inhibitors. This enzyme thus appears similar to the soluble activity from mammalian liver (88, 86). 5 -Nucleotidase in mammary gland hydrolyzes all 5 -ribonucleotides and shows a decrease from pregnancy to early lactation (76). Rats injected with glucagon show increased 5 -nucleotidase in pancreatic islet tissue (77). The enzyme in mouse kidney has been examined histochemically and electrophoretically and found to exist as isozymes (75). Electrophoretic techniques have also provided evidence that the enzyme exists as isozymes in many other tissues of the mouse such as liver, spleen, intestine, testes, and heart (79). 

Although gluconeogenesis is generally considered to be confined to liver and kidney, evidence for the presence of a specific FDPase in muscle has been reported from a number of laboratories. Significant levels of activity are to be found in skeletal muscle of a wide variety of vertebrates including mammals, birds, and amphibia (71, 72). The levels of activity in white muscle were reported to be similar to those found in liver and kidney, but the enzyme was not detected in heart muscle or in smooth muscle of several species tested. Fructose diphosphatase in crude muscle extracts has been reported to be stimulated by EDTA (72). 

Multiresidue determination of QUIN antibiotics using liquid chromatography coupled to ACPI-MS and MS/MS was also described (197). In the source, collision-induced dissociation was used to optimize fragmentation to produce mass spectra consisting of the protonated molecule and two characteristic fragment ions of nearly equal intensity. Selected ion monitoring of three ions per QUIN yielded a sensitive detection in catfish muscle extracts (detection limits of 0.8-1.7 yug/kg). An MS/MS was used to increase the specificity and selectivity of analysis. The preseparation step was very simple only the LLE procedure is required. 

Enormous efforts have been devoted to the analysis of the extractive components of fish muscles and much information has been accumulated. In recent years, the distribution of nitrogenous components in the muscle extracts of several species of fish has been elucidated almost completely (JJ, 10, 11, 12, 13). However, few studies have correlated these analytical data directly with taste. 

Table V. Nitrogenous compounds in the muscle extract of squids (N mg/100 g)...

Figure 1. The contents of glycine, proline, serine, and alanine in the muscle extracts of prawns and lobsters. They are arranged in decreasing order of palata-bility from left to right (341.

O Regan S, Fong JS, Drummond KN (1979) Renal injury after muscle extract infusion in rats absence of toxicity with myoglobin. Experientia 35 805-806... 

Blachar Y, Fong JS, de Chadarevian JP, Drummond KN (1981) Muscle extract infusion in rabbits. A new experimental model of the crush syndrome. Circ Res 49 114-124... 

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