Co-zymase

Go-dehydrogenase I, co-enzyme I or co-zymase, obtainable from extracts of yeast, muscle, liver and kidney, is the co-enzyme of sugar fermentation, and acts with the dehydrogenases of hexose diphosphate, malate, and alcohol, and also with the lactate dehydrogenase of muscle. 

Co-dalvdiogenaM I (co-enzyme I, co-zymase) (adenosine-ribose-dlphosphoric-ribose-nlcotinlc amide). 

Harden and Young showed that zymase required phosphate and a co-enzyme, co-zymase, in order to act. 

Harden and Young later showed that zymase solutions were inactivated by dialysis owing to the loss of two indispensable coactants, both of which were heat-stable. The first of these proved to be inorganic phosphate, the second was an organic compound, which Harden called the co-ferment of alcoholic fermentation. This organic factor, renamed co-zymase, or coenzyme I, was identified by Euler (p. 259). It is easily extracted from yeast by washing with water the residual mixtime of enzymes and activators has been termed apo-zymase. The fimction of... 

Meyerhof has shown that hexose phosphorylation requires Mg ions and co-zymase, which reacts with the sugar to yield hexose diphosphate and adenylic acid in a manner comparable to the action of adenine triphosphate as a phosphate carrier in muscle glycolysis. 

Co-enzyme I (co-zymase) acts as a hydrogen carrier in sugar fermentation and in muscle contraction, and various tissue oxidations. 

Co-enzyme I is a diphospho-pyridine nucleotide of adenine. Co-enzyme II (co-zymase) is a triphospho-pyridine nucleotide of adenine. Both co-enzymes act as hydrogen carriers in respiration (pp. 259, 330). The co-enzyme of D-amino acid oxidase is a diphospho-riboflavin nucleotide of adenine. 

Zymase (a mixture) yeast d-glucose, /-fructose alcohol. CO, and small quantities of glycerol 45-6-5... 

The study of the co-enzyme has established the fact that this substance is in reality very unstable. Its activity dinoinishes perceptibly in the presence of 2.5 per cent K2CQ3 at 35°, and is completely destroyed if maintained at 130 for 4 hours. The co-enzyme is indifferent to the action of the proteolytic enzymes, but is destroyed, on the contrary, vmder the influence of lipase, due to the setting free of phosphoric acid. As noted, this substance resembles in certain ways, particularly injts chemical nature, the anti-protease referred to above, but differs from the latter in its sensitiveness to alkalis and its lower resistance to heat. Anti-protease, in fact, not only is not capable of activating zymase, but it is not even destroyed by K2COJ, nor by heating 4 hours at 130 . 

The combination co-enzyme -1- zymase, which causes alcoholic fermentation, is influenced by other active substances which also come from the yeast. Notably it is sensitive to the action of endotryptase, lipase, and anti-protease. Endotryptase digests and destroys zymase. The juice, allowed to stand, gradually deteriorates as a result of a digestive action of the tryptic enzyme on the zymase. All the conditions which favor the activity of endotryptase (acidity of the medium, temperature of etc) are consequently detrimental to tire preservation... 

In the inactivation of the juice, from the point of view of alcoholic fermentation resulting from a more or less prolonged autolysis, two kinds of phenomena are observed. In the first case, the inactivation is produced because the co-enzyme has deteriorated. Under these conditions, the addition of boiled juice renews activity by restoring the required complement, the co-enzyme. Moreover, this addition of boiled juice will contribute greatly to the preservation of the fresh juice, for the co-enzyme and the anti-protease both protect the zymase from the destructive action of the endotryptase. This protection, however, will be of short duration. Lipase, present in the juice, will soon destroy the co-enzyme as well as the antibody, and a fresh addition of boiled juice will be necessary to cause a fresh activity in the deteriorated juice, a portion of zymase having been able to escape the action of the endotryptase. 

The ca e is quite otherwise when yeast juice is left for a long time to itself. Here, not only does the co-enzyme deteriorate, but even the zymase itself is digested or destroyed by the endotryptase. Under these conditions, the addition of co-... 

The first satisfactory experimental proof that alcoholic fermentation is caused by a non-organised ferment (enzyme) in yeast was given by Buchner, who adopted for it Bechamp s name zymase. Buchner found that if the yeast cells are crushed by trituration with sand and kieselguhr and the paste is pressed in a cloth bag, a liquid free from yeast cells is obtained which produces alcoholic fermentation. The activity is not destroyed by evaporation to dryness at 30 -35° or precipitation by alcohol. Arthur Harden and others showed that a co-enzyme, separable from yeast-juice by dialysis, and an inorganic phosphate, are also involved in alcoholic fermentation, the process being apparently very complicated. 

Pyridine nucleotides are the coenzymes longest known. In 1906, Harden and Young noticed that Buchner s zymase could be separated by ultrafiltration into a high molecular weight component and a low molecular weight component, or coenzyme. These results were later extended and served as a basis for theories of enzyme structure. This coenzyme (then called codehydrogenase I, coenzyme I, DPN, now NAD) was isolated by H. v. Euler and co-workers in 1931 shortly afterwards, Warburg and Christian discovered the closely related coenzyme II ( TPN, now NADP). 

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