mechanism of metabolism , 195 



Hydrolytic Enzymes 



Enzymes of Caebohydrates. — Enzymes which decompose carbo- 

 hydrates are very commonly found in nature, because carbohydrates 

 constitute a very extensive and common group of organic matter. 

 By far the largest part of the dry plant consists of cellulose, starch 

 and sugar. To decompose them, enzymes are necessary. The chem; 

 ical reaction. of these enzymes is hydrolytic; in other words, the larger 

 molecule is broken into smaller ones by the simple addition of water. 

 Thus, the cellulose-destroying enzyme, called cellulase or cytase, de- 

 composes the cellulose into soluble sugars after the following formula: 



CoHxoOe -f- H2O = C6H12O6 



or, considering that the cellulose molecule is really many times 

 CeHioOs, the formula will be more accurately written 



(C6Hio06)n -I- nHaO = nCsHiaOs 



which indicates at the same time that one cellulose molecule gives 

 many Sugar molecules. 



CeUulase is an enzyme which is quite difficult to obtain. Though 

 it must be produced by all the cellulose destroying molds and bacteria, 

 experiments have failed in some instances to prove its presence. It 

 is found in some wood destroying fungi and in some of the bacteria 

 causing the rot of vegetables. The organisms of certain plant diseases 

 force their way into the cell by dissolving the cellulose membrane by 

 an enzyme, while certain molds are able to puncture the cell wall 

 mechanically. 



Diastase, or amylase, is the starch-dissolving enzyme which is one 

 of the most common enzymes in nature. It is found in all green plants, 

 and it forms during the sprouting of starchy seeds. Many molds 

 and a few bacteria produce this enzyme, while yeasts generally cannot 

 decompose starch for lack of diastase. Starch has the same formula 

 as cellulose, and it is broken up into soluble sugars in the same way. 

 Much'*attention has been paid to this process by the chemists, and it 

 is found that the process is a gradual one, giving first dextrins, and 

 finally maltose (C12H22O11). The hydrolysis of starch expressed in 

 chemical symbols may be presented as follows: 



2(C6HioOB)n + nH20 = nCi2H220n. 



starch Maltose 



