Apparently the cleavage of the inosite phosphoric acid in the plant occurs 

 only during germination or when the material is digested in aqueous or 

 faintly acid solutions favorable to enzyme activity. 



THE EFFECT OF ENZYMES UPON INOSITE 

 PHOSPHORIC ACID 



Suzuki, Yoshimura and Takaishi (1907) observed that the amount 

 of inorganic phosphoric acid increased when wheat or rice bran was 

 allowed to stand in contact with water. These investigators were also 

 able to separate a preparation from rice bran which, when added to a 

 solution of phytin, ■ caused a rapid formation of inorganic phosphoric 

 acid and led finally to a complete hydrolysis of the phytin molecule into 

 inosite and phosphoric acid. This enzyme was termed phytase. The 

 existence of phytase has been demonstrated in other plant material and 

 in animal tissues by several investigators. McCollum and Hart (1908) 

 showed that enzymes extracted from various animal tissues were capable 

 of liberating inorganic phosphoric acid from phytin. Vorbrodt (1910) 

 showed that it was present in wheat, rye, barley, etc. Investigations by 

 Dox and Golden (1911) and by Jegorow (1913) demonstrated that cer- 

 tain fungi cause a cleavage of the phytin molecule with production of 

 inorganic phosphoric acid. Plimmer (1913) also found that certain 

 enzymes of animal tissue liberated inorganic phosphoric acid from phytin 

 but the most active phytase was contained in wheat bran. 



We have studied quantitatively the activity of the wheat bran phy- 

 tase by determining the amounts of inorganic phosphoric acid formed 

 on digesting wheat bran in water or dilute acids (Anderson 1915 (3)). 

 The enzyme is very active in aqueous solutions and also in 0.1 per cent, 

 or 0.2 per cent, hydrochloric or acetic - acid. The hydrolysis of the 

 inosite phosphoric acid begins at once and proceeds with great rapidity. 

 After digesting wheat bran in water for thirty minutes about 45 per 

 cent, of the soluble phosphorus is inorganic and after 24 hours about 88 

 per cent, of the total soluble phosphorus is present as inorganic phos- 

 phoric acid. The enzyme is very sensitive to certain concentrations of 

 hydrochloric acid. Greater amounts of free phosphoric acid are lib- 

 erated when the bran is digested in 0.1 or 0.2 per cent, hydrochloric acid 

 than when distilled water is used, but when the bran is digested in 0.3 

 per cent, hydrochloric acid the activity of the enzyme is almost entirely 

 inhibited. With increasing strength of hydrochloric acid the amount of 

 inorganic phosphoric acid in the extract decreases, the minimum amount 

 being obtained when 1.0 per cent, hyrochloric acid is used. The activity 

 of the enzyme is likewise inhibited or destroyed by 0.25 per cent, am- 

 monia or by the action of boiling water, as well as by exposing the bran 

 for a short time to the action of 0.5 per cent, hydrochloric acid. 



Boutwell (1917) has also studied the activity of the wheat bran 



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