Enzymes are often used as nonrecoverable chemical reagents, in which case they are added to the substrate incubated at the required temperature and pH for a period and subsequently destroyed. Amylase, proteases and other inexpensive bulk enzymes are used in this way. Alternatively, enzymes may be attached to an inert support (immobilized). This offers the advantages of (1) recovery and re-use of the enzymes, in batch reactors; or (2) the development of continuously operated enzyme reactions similar to continuous fermentation systems used for microorganisms; (3) the possibility of multi-enzyme systems; and (4) the enzyme does not remain in the processed solution. However, there are some disadvantages, the enzyme may be stabilized by immobilization but it may also lose activity, and the process becomes technically more complex.

There are many ways to immobilize enzymes, the common procedures involve (1)absorption to an insoluble support of either organic or inorganic origin. Cellulose, dextran, nylon and bentonite are some of the many carriers that have been used. Attachment may be by physical adsorption, ionic binding or covalent bonding. (2) Entrapment methods in which the enzyme is localized within a polymer matrix are popular and include gel or fiber entrapment and microencapsulation in which the enzyme is enclosed within sperical semipermeable polymer membranes. (3) A simple but effective procedure is to immobilize the enzyme within the host cell by heat treatment or covalent cross-linking following by pelleting the cells.

Are the following statements true or false?

（1）Amylase, proteases and other inexpensive bulk enzymes are destroyed after the enzyme-catalyzed reaction is completed

（2）The advantages of immobilization of the enzymes include the stability of the enzymes and the increase of the enzyme activity

（3）By immobilization of the enzymes, it is possible to operate the enzyme reactions continuously

（4）In the last paragraph, the word “insoluble support” has the same meaning as the word “carrier”