In 1894 and 1895, Fischer, in a remarkable series of papers on the influence of molecular structure upon the action of the enzyme, showed that various species of yeast behave very differently towards solutions of sugars.
Fischer found that the enzyme "invertase," which is present in yeast, attacks methyl-d-glucoside but not methyl-l-glucoside.
Although the action of zymase may be regarded as mechanical, the enzyme cannot be produced by any other than living protoplasm.
Such an enzyme is the pepsin of the stomach of the higher animals.
A third enzyme, the trypsin of the pancreas, possesses the power of both pepsin and erepsin.
Another enzyme, rennet, which in the animal body is proteolytic, is frequently met with in plants, but its function has not been ascertained.
The digestion of fat or oil has not been adequately investigated, but its decomposition in germinating seeds has been found to be due to an enzyme, which has been called lipase.
It has been ascertained that in many cases this decomposition is effected by the secretion of an enzyme, which has been termed zymase.
The irritation set up by the hatching egg and its resulting larva appears to be the stimulus to development, and net a poison or enzyme injected by the insect.
Dubois (1886), who considers that the luminosity is due to the influence of an enzyme in the cells of the organ upon a special substance in the blood.
Of especial note is the transformation of maltose by maltase into glucose, and of cane sugar by invertase into a mixture of glucose and fructose (invert sugar); other instances are: lactose by lactase into galactose and glucose; trehalose by trehalase into glucose; melibiose by melibiase into galactose and glucose; and of melizitose by melizitase into touranose and glucose, touranose yielding glucose also when acted upon by the enzyme touranase.
There is present in the seeds an enzyme which rapidly decomposes the oil if the seeds are crushed and kept, setting free a fatty acid and glycerin.
It occurs free in bitter almonds, being formed by an enzyme decomposition of amygdalin.
That such enzymes are formed in the protoplasm is evident from the behaviour of hyphae, which have been observed to pierce cell-membranes, the chitinous coats of insects, artificial collodion films and layers of wax, &c. That a fungus can secrete more than one enzyme, according to the materials its hyphae have to attack, has been shown by the extraction of diastase, inulase, trehalase, invertase, maltase, raffinase, malizitase, emulsin, trypsin and lipase from Aspergillus by Bourquelot, and similar events occur in other fungi.
- Taken in conjunction with Pfeffer's beautiful discovery that certain chemicals exert a distinct attractive influence on fungus hyphae (chemotropism), and the results of Miyoshi's experimental application of it, the phenomena of enzyme-secretion throw considerable light on the processes of infection and parasitism of fungi.
On a successful wither the amount of the tea ferment or enzyme is dependent.
This, like the excretion of the sundew and other insectivorous plants, contains a digestive ferment (or enzyme) which renders the nitrogenous substances of the body of the insect soluble, and capable of absorption by the leaf.
Lea and Miguel further proved that the hydrolysis is due to an enzyme - urase - separable with difficulty from the bacteria concerned.
Considerable differences occur in these latter respects, however, and interesting results were obtained by Beyerinck with mixtures of species possessing different powers of enzyme action as regards carbohydrates.
In the case of diphtheria Sidney Martin obtained toxic albumoses in the spleen, which he considered were due to the digestive action of an enzyme formed by the bacillus in the membrane and absorbed into the circulation.
But this has not been proved, and hitherto no enzyme has been separated from a pathogenic bacterium capable of forming, by digestive or other action, the toxic bodies from proteids outside the body.