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5 Effect of Fat-Solvent Anesthetics

peroxidase, pyrogallol, light, amount and quantity


Saturation of the potato-juice or blood with ether or chloroform does not affect its power to produce light with pyrogallol ± A sam ple of horseradish-root extract preserved 45 days under ether gave a good light when mixed with pyrogallol ± 6. Is THE OXIDASE A CATALYSER? That oxidases in general are not catalyzers, but are used up in the reaction has been proven by the work of Kastle (is), who found that the amount of phenolphthalein oxidized is proportional to the quantity of blood present, and of Bach and Chodat (a and 42), who found that the amount of pyrogallol oxidized to purpurogallin is proportional to the amount of peroxidase and also to the amount of present, but independent of the quantity of pyrogallol, providing the pyrogallol is present in excess of the quantity capable of being oxidized by per oxidase and Melanin formation by tyrosinase is also propor tional to the amount of tyrosinase present (42).

The peroxidase, therefore, transfers the 0 of to the pyrogallol and the 11202 pyrogallol, and peroxidase are all changed—i. e., used up in the reaction. If we represent the peroxidase by P and the pyro gallol by B the reaction must take place as follows: Note that in the first equations the peroxidase (P) is used up and in the second equations it acts as a true catalyzer and is regenerated again.

That the peroxidase of turnip-juice is used up so far as its power to cause light-production in pyrogallol is concerned is indicated in the following experiment: If 1 c.c m/10 pyrogallol+4 c.c. (3 per cent) is mixed with 5 c.c. turnip-juice heated to 80° (to destroy the catalase and weaken the peroxidase), a very faint light is produced. A small amount of per

oxidase is, therefore, present. The mixture is allowed to stand for 24 hours at 22° C. and then fresh turnip-juice is added. A good light results, showing that the pyrogallol has not been changed by a small amount of peroxidase when a long time has been allowed for the re action to proceed. The pyrogallol was turned a light brown by the smell amount of peroxidase, and this color had not deepened in 24 hours, but did deepen immediately when the additional quantity of peroxidase was added. A small quantity of "enzyme" can not, therefore, transform an indefinite amount of pyrogallol. A similar result was obtained with a weak hemoglobin solution, 0.1 per cent dried blood-extract.

That a large quantity of peroxidase can be used up by addition of successive amounts of pyrogallol—i. e., by "titrating" the peroxidase can be shown as follows: To 10 c.c. potato-juice heated to 60° C. (to destroy catalase and consequent foaming due to liberation of 0 from is added 2 c.c. of a mixture of equal parts m/10 pyrogallol and 3 per cent Light results. When this has disappeared (about 2 to 3 minutes) 2 more cubic centimeters of the mixture are added and a very faint light results. On adding a further 2 c.c. no light appears. There is, however, in the final mixture plenty of to produce light, as may be shown by adding fresh potato-juice when abundant light appears. The peroxidase has been completely used up. A similar experiment with blood-extract gave a similar result.