Enzymes and their applications / By Dr. Jean Effront ... English translation by Samuel C. Prescott ... v. 1. The enzymes of the carbohydrates. The oxidases.

  • Effront, Jean, 1850-1931.
Date:
1902
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Licence: Public Domain Mark

Credit: Enzymes and their applications / By Dr. Jean Effront ... English translation by Samuel C. Prescott ... v. 1. The enzymes of the carbohydrates. The oxidases. Source: Wellcome Collection.

Provider: This material has been provided by the Augustus C. Long Health Sciences Library at Columbia University and Columbia University Libraries/Information Services, through the Medical Heritage Library. The original may be consulted at the the Augustus C. Long Health Sciences Library at Columbia University and Columbia University.

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    in time the property of giving color, and that the best way is. to make the tincture before the experiment by grinding powder of guaiacum with alcohol; moreover, the use of this reagent always offers certain difficulties: it must be noted that the coloring matter formed is not very stable, that it is decomposed by heat as well as by different chemical re- agents. A slight alkalinity or even a slight acidity is suf- ficient to prevent the production of coloration, and it fol- lows that it is necessary to take some precautions when using this reagent. It is well first to neutralize exactly the hydro- gen peroxide used, for this is generally very acid; it is also well to measure the degree of acidity or alkalinity of the liquid containing the diastase to be studied, then to neu- tralize it when it is clearly alkaline or clearly acid. The coloration produced by guaiaconic acid is not destroyed by acetic acid and it is often of advantage, when working with an absolutely neutral solution, to acidify it with. a drop of dilute acetic acid. The reaction of the tincture of guaiacum is of much use in the investigation of enzymes. However, this reagent is not absolutely reliable, for the coloration observed in a solu- tion may be due to other bodies than enzymes. Moreover, if a reaction is not obtained, one must not conclude that the liquid does not contain an active substance, for the coloration may be prevented by different substances which may be pres- ent with the enzymes in the liquid tested. Moreover, enzymes are known which do not give colora- tion with guaiacum and, on the other hand, diastases which, after having been submitted to certain influences, lose this property without always losing their activity. Thus, at a high temperature, certain enzymes no longer give coloration with guaiacum, although the active substance is not destroyed. With other diastases the property of coloring tincture of guaiacum disappears in a prolonged contact with hydrogen peroxide, contact which has no influence on the activity of the diastase. However, no enzymes are known