A text-book of physiological chemistry / Olof Hammarsten ; authorized translation from the author's enlarged and revised 4th German edition by John A. Mandel.

  • Hammarsten, Olof, 1841-1932.
Date:
1900
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Licence: In copyright

Credit: A text-book of physiological chemistry / Olof Hammarsten ; authorized translation from the author's enlarged and revised 4th German edition by John A. Mandel. Source: Wellcome Collection.

    27/652 (page 11)
    ENZ YMES. The enzymes may be extracted from the tissues by means of water or glycerin, especially by the latter, which forms very stable solutions and conse(piently serves as a means of extracting them. The enzymes, generally speaking, do not appear to be diffusible. They are readily carried down witli other substances when these precipitate in a finely divided state, and this property is extensively taken advantage of in the preparation of pure enzymes.' The property of many enzymes of decomposing hydrogen peroxide is, according to Alex. Schmidt, not dependent upon the enzyme, but is caused by the contamination of the enzyme with constituents from the j)rotoplasm. This coincides with the observations of Jacousen on emulsin, pancreas enzyme, and diastase, that the catalytic pro]>erty may be destroyed by proper means without diminishing the specific enzymotic action. The continued heating of their solutions above -f- 80'^ (J. generally destroys most of the enzymes. In the dry state, however, certain enzymes may be heated to 100° or indeed to 150°-160° C. without losing their power. The enzymes are precipitated from their solutions by alcohol. AVe have no characteristic reactions for the enzymes in general, and each enzyme is characterized by its specific action and by the conditions under which it operates. But it must be stated that, however the different enzymes may vary in action, they all seem to have this in common, that by their presence an impulse is given to split more complicated combinations into simpler ones, whereby the atoms arrange themselves from an unstable equilibrium into a more stable one, chemical tension is transformed into living force, and new products are formed with lower heat of combustion than the original substance. The presence of water seems to be a necessary factor in the perfection of such decompositions, and the chemical process seems to consist in the taking up of the elements of water. The action of the enzymes may be markedly influenced by external con- ditions. The reaction of the liquid is of special importance. Certain enzymes act only in acid, others, and the majority, on the contrary, act only in neutral or alkaline liquids. Certain of them act in very faintly acid as well as in neutral or alkaline solutions, but best at a specific reaction. The temperature exercises also a very imj^ortant influence. In general the activity of enzymes increases to a certain limit with the temperature. This limit is not always the same, but depends, like the destructive action of liigh temperatures, essentially upon the quantity of enzyme and other con- ditions.’ The products of the enzymotic processes exercise a retarding ' Hi iicke, AVieiier Sitzungsbericlit, Bd. 43. 1861. ’ Al. Schmidt, Zur Blutlelire. Leipzig, 1892.Jacobseu, Zeilscbr. f. idiysiol. Chemie, Bd. 16, S. 340. 2 Tammanii, Zuitschr. f. physiol. Chem., Bd. 16, S. 371 ; Pugliesie, Pflugcr’s Arch., Bd. 69.