Page:Defensive Ferments of the Animal Organism (3rd edition).djvu/126

 that the key can fit into the guide, and push back the bolt. The whole of the rest of the lock may, in this case, have suffered considerable alterations.

The ferments attack a particular substrate at a particular point, and very probably always combine with the groups against which they are directed. It is only secondarily that disturbance occurs of the equilibrium of the compound. So long as this point of attack remains unchanged the ferments are able to act, but the conditions become very different when the much altered product, with all its groupings, is brought into the circulation. If the decomposition is to be a complete one, then a number of ferments has to act. The new conditions, caused by the denaturation, produce their full effect after the introduction into the circulation. When we search for ferments by means of boiled tissues, we expose a variety of proteins to the action of ferments. Only that grouping of atoms, towards which the ferment is directed, has to be considered here. All other groups may be neglected, because it would be scarcely possible to presume that the boiling has produced structural conditions which are accessible to ferments, although the natural substrate was not so accessible. Rather must we reckon with the possibility that a too extensive denaturation will so strongly modify an original grouping, that is accessible to ferments, that the ferment then becomes inactive. The grouping has now become foreign to it.