Page:The New International Encyclopædia 1st ed. v. 07.djvu/156

* ENZYME. 132 ENZYME. EN'ZYME (MGk. frjv/ws, e>,:i/»ios, leavened, from Gk. ir, en, in + ft/iy, syme, leaven). A name applied to any one ol a certain group of substances that occur in plains and in animals, and have the power of decomposing various car- bon compounds when brought into contact with them. They were formerly called 'unorganized ferments.' to distinguish them from yeasts and bacteria ('organized ferments'), which produce similar changes. The distinction has no value; for it has been shown that the action of the so- called organized ferments is usually due to en- secreted by them. Little is known of the chemistry of the enzymes; indeed, there is no ble test of their presence except their ac- and no way of establishing their purity. When prepared by any of the usual methods they are certainly mixed with other substances. Nev- ertheless, many known facts point to their pro- teid nature, and it is even conjectured that they are nucleo-proteids. Enzymes are produced in all kinds of plants. They may generally be obtained elements of water and is at the same time split up chemically. One class of enzymes, however, causes oxidation, and two enzymes are known which split up compounds without introducing other atoms into their molecules. The following are examples of these changes: ( 1 ) An hydrolysis effected by the enzyme in- vertase : + H 2 = C„H.A Water Glucose oxidation effected by Cane-sugar (2) An lactase: 2C 6 H,(OH) Hydroquinone + CH^O. Fructose the enzyme + 2 2C 6 H,0 2 Quinooe
 * 2H 2

Water (3) A decomposition effected by the enzyme myrosin : C.oH^NKS-O = C 3 H 5 CNS + C s H 12 0„ + KHSO, Sinigriu Allyl sulpho- Glucose Acid cyanate potasBiuui sulphate The principal enzymes, their distribution, the substances they attack, and the chief products of their action are shown by the following table: ENZYME Occurrence Substances attacked Product of the action ( Maltose. ( Glucose. i Alcohol, j Glucose. l Glucose, f Galactose, t Glucose, Rosacete, Euphorbiacete, 1 Fungi J "" Various subs. ( Giucose, "1 Red pigment, j Glucose, I Rnamnin. j Glucose, " I Wlntergreen oil. j Proteoses, '*" ( Peptones, etc. 1 l'rott'ost'M. Germinating seeds ) Carnivorous plants j "" | Peptones, Amides. ( Glycerin. i-i>i fruits and various) leaves ) Pectic acid. "■ f Forms Jelly. bing nr grinding the plant tissue, cxtraet- ing ii for twenty-four hours with several vol- ropriate olvenl I water, salt solu- iii : ii. alcohol, etc. i. filtering precipitating bj the addition of an excess of al- cohol i neutral salt. The substances thus obtained ] be 'what purified by washing, e< i ing to a process of di- alysis, action of enzymes is probably a chemical lovi ly decomposed in tin pr< iffected at all) thai it i he a<- ti'in di the enzyme and the acted upon takes up the The action of enzymes depends to a remarkable extent upon the temperature, the presence of free acids or alkalies, various salt:-, etc. Enzymes are inactive at low temperatures (below 10° C.) and again at high temperatures (above 60° or 70° C). They are destroyed at 70° to 80° C. Mosl of them act best at temperatures between 30° and 50° C. (86° to 122° F.). It has 1 it shown thai one enzyme, diastase, is destroyed by light, particularly by blue or violet light. The origin of those enzymes which have been investigated seems to be indirect, substances called zymogens being produced by the active cells, The zj ns appear as minute granules in the protoplasm which is about to form en- zymes, and under appropriate conditions are
 * l V atty acids.
 * i one of hydroly-