Inositol Phosphate Phosphatases of Microbiological Origin. Some Properties of the Partially Purified Phosphatases of Aspergillus ficuum NRRL 3135

Abstract

Partially purified samples of the acid phosphatase (EC 3.1.3.2) and of the phytase (EC 3.1.3.8) from A. ficuum were prepared by gel-filtration and ion-exchange dextran chromatography.The pH optimum in o· 02M phthalate buffer of the acid phosphatase was found to be 2·2, while in the same buffer the phytase was found to have at least two optima at pH 2·5 and 5·3, with the suggestion of a third at pH 2·8.The Km value of the acid phosphatase was 1 ·27 x 10-4M with sodium myo-inositol hexakisphosphate as substrate at pH 2· 2. Similarly the Km value of the phytase at pH 2· 5 was 2·44 x 10-sM and at pH 5·3 it was 1·29 x 10-SM.Of a range of inositol hexakisphosphates tested as substrates the order of ease of hydrolysis wasfor the phytase at pH 5·3.The major pentakisphosphate produced by the acid phosphatase at pH 2·2 from both D-chiroand L-chiro-inositol hexakisphosphate was the respective 1,2,3,4,6-pentakisphosphate. In the case of the phytase, at both pH 2·5 and 5·3 the major pentakisphosphate products were the 1,2,3,4,6-and the 1,2,3,5,6-isomers from the D-chiro-and L-chiro-substrates respectively.Neither enzyme was inhibited by 1 mM oxalate, 1 mM citrate, 1 mM EDTA or 1 mM (+ )-tartrate The activity of the acid phosphatase was reduced to 17% and that of the phytase at pH 2·5 to 69% by 1 mM fluoride. The phytase was not inhibited at pH 5·3 by any of the anions tested.

Comparative evaluation of the efficacy of cereal and microbial phytases in growing pigs fed diets with marginal phosphorus supply

“…With decreasing pH, plant phytase activities are extremely low, 25,26 whereas microbial phytase still exhibits 60% of its original activity at pH 2.0. 27,28 Thus it can be assumed that microbial phytase is still active in the fundic region of the stomach of the pig. In conclusion, microbial phytases are more efficient in hydrolysing phytate than plant phytases.…”

Expression, Gene Cloning, and Characterization of Five Novel Phytases from Four Basidiomycete Fungi: Peniophora lycii, Agrocybe pediades , a Ceriporia sp., and Trametes pubescens

“…One exception is an alkaline phytase from lily pollen that initially hydrolyzes the 5-phosphate group (1). Previously, phytases of microbial origin such as A. niger (11), Neurospora crassa (12), and Pseudomonas phytase (6) were generally considered to belong to the 3-phytases, while 6-phytases such as wheat bran phytase (21) were believed to be restricted mainly to the plant kingdom. Exceptions are the 6-phytases from Paramecium (26) and E. coli (10) and now the 6-phytases reported here.…”

Ethanol stimulates phospholipid turnover and inositol 1,4,5-trisphosphate production in Chlamydomonas eugametos gametes

“…To control whether the high levels of Ins(l,4,5)P 3 detected in extracts of ethanol-treated cells were due to non-specific competition for the binding protein, extracts of gametes treated for 30 min in ethanol were treated with excess phytase that breaks down inositol polyphoshates (Irving and Cosgrove 1972). Extract (100 Ixl, prepared as above) was incubated with 5 mg phytase from Aspergillusficuum (Sigma Chemical Co. St. Louis, Mo., USA) at 37 ~ C for 3 h. An equivalent ~m0unt.…”