Glycolytic enzymes muscle

For example, each subunit of the dimeric glycolytic enzyme triosephos-phate isomerase (see Figure 4.1a) consists of one such barrel domain. The polypeptide chain has 248 residues in which the first p strand of the barrel starts at residue 6 and the last a helix of the barrel ends at residue 246. In contrast, the subunit of the glycolytic enzyme pyruvate kinase (Figure 4.5), which was solved at 2.6 A resolution in the laboratory of Ffilary Muirhead, Bristol University, UK, is folded into four different domains. The polypeptide chain of this cat muscle enzyme has 530 residues. In Figure 4.5, residues 1-42... 

A decreased glycolytic rate has been proposed as a cause of muscle fatigue and related to pH inhibition of glycolytic enzymes. Decreasing pH inhibits both phosphorylase kinase and phosphofructokinase (PFK) activities. PFK is rate determining for glycolytic flux and therefore must be precisely matched to the rate of ATP expenditure. The essential characteristic of PFK control is allosteric inhibition by ATP. This inhibition is increased by H and PCr (Storey and Hochachka, 1974 ... 

Paul I wanted to come back to the issue of mitochondria and Ca2+. I happen to have friends on both sides of that issue. We have been promoting the idea, which seems to work in a variety of tissues, that subsarcolemmal space is highly populated by glycolytic enzymes. This is true in skeletal muscles also. One of the first things seen with ouabain is that it kills the lactate production without touching oxygen... 

Patients with this deficiency present with myopathy, recurrent aching muscles and myoglobinuria after prolonged exercise or starvation. It is interesting to note that there are more cases of a deficiency of this enzyme in muscle than there are cases of a deficiency of any of the glycolytic enzymes (including phosphorylase, see Chapter 6). 

Seminal vesicles Fructose Prostaglandins Potassium ions Fuel for sperm Not known but may stimulate contractions of smotth muscle in wahs of vagina and uterus Required by glycolytic enzymes... 

This is similar to the situation when, if all the glycolytic enzymes, plus activators and co-factors are placed together, in a flask or tube, glucose will be converted to lactic acid or ethanol, i.e. a mixture of enzymes plus co-factors can carry out a process that occurs in a living cell (e.g. muscle or yeast). Such experiments on the enzymes of glycolysis, in a flask, were hrst performed by Th. Buchner over 100 years ago. 

In contrast to milk, where samples are primarily derived from cows, meat analysis has to be performed in samples of a widely different animal origin including cattle, lamb, swine, poultry, and fish. Muscle is a complex matrix with a pH of 5.7, composed of muscle fibers, various types of connective tissue, adipose tissue, cartilage, and bones. Sarcoplasmic proteins such as myoglobin, and glycolytic enzymes are soluble in water while the myofibrillar proteins such as myosin and actin are soluble in concentrated salt solutions (14). The connective tissue proteins, collagen and elastin, are insoluble in both solvents. 

Hinterleitner, S., Platzer, U. and Wieser, W. (1987). Development of the activities of oxidative, glycolytic and muscle enzymes during early larval life in three families of freshwater fish. Journal of Fish Biology 30,315-326. 

In brain tissues, specific isoforms of glycolytic enzymes are also expressed there are specific brain isoforms for PFK (PFK-C), fructose-1,6-bisphosphate aldolase (aldolase C), enolase (enolase y), but not for GAPDH. The isoforms bear the same catalytic functions however, they could be specialized to form different ultrastructural entities. For example, muscle PFK (a dissociable tetrameric form) binds to microtubules and bundle them [94, 95], however, the brain isoenzyme (stable tetramer) does not [96]. 

Wojtas, K., Slepecky, N., von Kalm, L., Sullivan, D. Flight muscle function in Drosophila requires colocalization of glycolytic enzymes. Mol. Biol. Cell 1997, 8 1665-1675. 

Sullivan, D. T., MacIntyre, R., Fuda, N., Fiori, J., Barrilla, J., Ramizel, L. Analysis of glycolytic enzyme co-localization in Drosophila flight muscle. J. Exp. Biol. 2003, 206 2031-2038. 

Baldwin, K.M., W.W. Winder, R.L. Terjung, and J.O. Holloszy (1973). Glycolytic enzymes in different types of skeletal muscle adaptation to exercise. Am. J. Physiol. 225 962-966. 

SP3 REGULATION OF GENES FOR MUSCLE-SPECIFIC GLYCOLYTIC ENZYMES... 

Somero, G.N., and J.J. Childress (1980). A violation of the metabolism-size scaling paradigm activities of glycolytic enzymes in muscle increase in larger size fishes. Physiol. Zool. 53 322-337. 

In a muscle homogenate, actin-myosin was found to have formed complexes that were able to settle on the chromatographic material. Moreover, the actin-myosine complexes bound various glycolytic enzymes.20 An elution profile resulting when lactate dehydrogenase was being purified from muscle homogenate is shown in Fig. 3. 

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