The purification and properties of myo-inositol monophosphatase from bovine brain.
1. An inositol monophosphatase was purified to homogeneity from bovine brain. 2. The enzyme is a dimer of subunit Mr 29,000. 3. The enzyme hydrolyses both enantiomers of myo-inositol 1-phosphate and both enantiomers of myo-inositol 4-phosphate, but has no activity towards inositol bisphosphates, inositol trisphosphates or inositol 1,3,4,5-tetrakisphosphate. 4. Several non-inositol-containing monophosphates are also substrates. 5. The enzyme requires Mg2+ for activity, and Zn2+ supports activity to a small extent. 6. Other bivalent cations (including Zn2+) are inhibitors, competitive with Mg2+. 7. Phosphate, but not inositol, is an inhibitor competitive with substrate. 8. Li+ inhibits hydrolysis of inositol 1-phosphate and inositol 4-phosphate uncompetitively with different apparent Ki values (1.0 mM and 0.26 mM respectively).
Gee
N S
NS
Merck Sharp and Dohme Research Laboratories, Neuroscience Research Centre, Harlow, Essex, U.K.
Ragan
C I
CI
Watling
K J
KJ
Aspley
S
S
Jackson
R G
RG
Reid
G G
GG
Gani
D
D
Shute
J K
JK
D000818:Animals; D001921:Brain / Q000201:enzymology*; D002413:Cations, Divalent / Q000494:pharmacology; D002417:Cattle; D002846:Chromatography, Affinity; D002850:Chromatography, Gel; D007700:Kinetics; D008094:Lithium / Q000494:pharmacology; D008970:Molecular Weight; D010744:Phosphoric Monoester Hydrolases / Q000037:antagonists & inhibitors / Q000302:isolation & purification* / Q000378:metabolism; D011489:Protein Denaturation; D013379:Substrate Specificity; D014508:Urea / Q000494:pharmacology
D002413:Cations, Divalent; D014508:Urea; D008094:Lithium; D010744:Phosphoric Monoester Hydrolases; C021822:myo-inositol-1 (or 4)-monophosphatase