title: Preparation of homogeneous crystals of myo-inositol 1-phosphate synthase from rat testicles--further data on the chemical and catalytic properties of the enzyme (studies on the biosynthesis cyclitols, XXXIX).
abstract: Pre-purified preparations of myoinositol-1-phosphate synthase (E.C. 5.5.1.4) from rat testes can be purified to homogeneity by first crystallizing the enzyme according to JAKOBY and then recrystallizing it at a pH value close to the isoelectric point while slowly increasing the temperature from 0 to 15 degrees C. This method gives a much yield of homogeneous enzyme than the previously used purification by affinity chromatography. It was further found that the pure enzyme contains close to 2 mol NAD+ per mol enzyme; it does not contain any metal. At substrate saturation the enzyme binds close to 1 mol substrate per mol enzyme, as determined by using radioactively labelled substrate and binding it to the enzyme by reduction with NaBH4. The reaction catalyzed by the enzyme is irreversible.
mesh_terms: D000818:Animals; D002238:Carbohydrate Epimerases / Q000302:isolation & purification*; D003460:Crystallization; D008297:Male; D007296:Myo-Inositol-1-Phosphate Synthase / Q000302:isolation & purification* / Q000378:metabolism; D009243:NAD / Q000032:analysis; D011485:Protein Binding; D051381:Rats; D013737:Testis / Q000201:enzymology*
chemical_list: D009243:NAD; D002238:Carbohydrate Epimerases; D007296:Myo-Inositol-1-Phosphate Synthase