title: Purification and characterization of a secreted purple phosphatase from soybean suspension cultures.
abstract: We purified and partially sequenced a purple (lambda(max) = 556 nanometers) acid phosphatase (APase; EC 3.1.3.2) secreted by soybean (Glycine max) suspension-culture cells. The enzyme is a metalloprotein with a Mn(2+) cofactor. This APase appears to be a glycoprotein with a monomer subunit molecular weight of 58,000 and an active dimer molecular weight of approximately 130,000. The protein has an isoelectric point of about 5.0 and a broad pH optimum centered near 5.5. The purified enzyme, assayed with p-nitrophenyl phosphate as the substrate, has a specific activity of 512 units per milligram protein and a K(m) of approximately 0.3 millimolar; phosphate is a competitive inhibitor with a K(i) of 0.7 millimolar. This APase is similar to one found in soybean seed meal but dissimilar to that found in soybean seedlings.
authors: Department of Biology, Texas A&M University, College Station, Texas 77843.
authors: B R
authors: BR
authors: Lebansky
authors: T D
authors: TD
authors: McKnight
authors: L R
authors: LR
authors: Griffing