Constancy of the optimum temperature of an enzyme under varying concentrations of substrate and of enzyme / by Arthur Compton.

  • Compton, Arthur.
Date:
1914
Catalogue details

Licence: In copyright

Credit: Constancy of the optimum temperature of an enzyme under varying concentrations of substrate and of enzyme / by Arthur Compton. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    Maltose hydrolysed (%) 16 hours’ incubation the tubes were withdrawn, the corks removed, and each rapidly washed with 1 cm.I 2 3 of water, the washings being carefully added to the contents of the corresponding tube. The tubes were next heated for five minutes in boiling water to stop the enzyme action, they were then cooled, and the contents of each diluted to a known volume, such that 20 cm.3 of the diluted mixture corresponds to 36 mgrm. of maltose. The proportion of maltose hydrolysed was estimated by the increase of reducing power as determined by the method of Bertrand (ibid.). The numbers obtained are recorded in Table II. If the percentage of maltose hydrolysed be plotted against the mean tem- perature of the experiment these numbers give the series of curves represented by fig. 1. Each curve shows a maximum at or about the same point, +47°. Hence, under the conditions of the experiment, the optimum temperature of the ferment is constant, and independent of the variations in the concentration of the substrate. That the optimum temperature is also independent of the concentration of the enzyme is shown by the following experiments :—Four solutions of the enzyme were prepared containing 10,30, 60 and 100 mgrm. dissolved in 10 cm3. I iQ. 1. Substrate concentrations M/5 to M/30. Enzyme concentration 2 x 10~3 grin, per cm.-' Fio. 2. Substrate concentration M/20. Enzyme concentrations 2 x 10~4 to 20 x 10-4 grm. per cm.3