CY'TASE (from Gk. zairos, kytos, cavity, cell). An enzyme that attacks the cell-walls of plants and alters the chemical composition of sonic of the components so that the walls swell up in water, become translucent, and finally dis solve. The process is one of digestion. It is not yet known whether what is called cytase is a single enzyme or several, no sufficient study having been possible. Cytase has been found in the hyphen of various fungi which live as para sites in plants. destroying their tissues. it has also been identified in the seeds of many grasses, in which it is secreted chiefly by the 'gluten layer' (a layer of cells outside the starch-bear ing ones). and in the seeds of certain nosa‘, palms. etc. In many seeds the re.terve food is stored as cellulose in the farm of thickened walls, making the food-bearing tissue, the endo sperm (q.v.). of bony hardness—e.g. vegetable ivory, the seed of a palm (Phytrlcphas Indira).
In this seed certainly, and probably in all such seeds, cytase is produced at germination to digest the reserve cellulose and render it available as food for the growing embryo. Since the substances which take part in the formation of cell-walls are numerous and diverse, and their composition is still uncer tain, no adequate knowledge has been obtained as to the products of their digestion by cytase. From the cellulose constituents one or more sugars are produced, possibly by hydrolysis, through dextrins. Cytase acts only on cellulose walls, being unable to attack lignified or cuti nized walls. It acts most energetically in a weakly acid medium, but is destroyed by tem peratures of tiO to Or C. It may be obtained (mixed with diastase) from malt by the method described under DIASTASE (q.v.). See also ENZYMES; and DIGESTION.