title: Invertase inhibitors from sweet potato (Ipomoea batatas): purification and biochemical characterization.
abstract: Two proteinaceous invertase inhibitors, designated ITI-L and ITI-R, were purified to electrophoretic homogeneity. ITI-L was purified from acetone powder of sweet potato leaves through sequential steps entailing buffer extraction, acid treatment, DEAE-Sephacel ion-exchange chromatography, and Sephacryl S-100 gel filtration. ITI-R was purified from sweet potato tuberous roots by sequentially applying buffer extraction, Con A-Sepharose affinity chromatography, DEAE-Sephacel ion-exchange chromatography, Sephacryl S-200, and Superose 12 gel filtration. The optimal pHs for interaction between ITI-L and ITI-R and acid invertase from sweet potato leaves were 5.5 and 5.0, respectively. The molecular masses of ITI-L and ITI-R were 10 and 22 kDa, respectively, as estimated by both gel filtration and SDS-PAGE. Both inhibitors were thermostable (90% of the activity remained after incubation at 100 degrees C for 20 min), and Western blotting showed them to be immunologically related.
authors.affiliation: Department of Agricultural Chemistry, National Taiwan University, Taipei 106, Taiwan.
authors.forename: Yung-Liang
authors.initials: YL
authors.lastname: Wang
authors.forename: Chang-Yi
authors.initials: CY
authors.lastname: Wu
authors.forename: Chen-Tien
authors.initials: CT
authors.lastname: Chang
authors.forename: Hsien-Yi
authors.initials: HY
authors.lastname: Sung
mesh_terms: D000595:Amino Acid Sequence; D004791:Enzyme Inhibitors / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D027723:Ipomoea batatas / Q000737:chemistry*; D008970:Molecular Weight; D010446:Peptide Fragments / Q000737:chemistry; D018515:Plant Leaves / Q000737:chemistry; D018517:Plant Roots / Q000737:chemistry; D043324:beta-Fructofuranosidase / Q000037:antagonists & inhibitors*
chemical_list: D004791:Enzyme Inhibitors; D010446:Peptide Fragments; D043324:beta-Fructofuranosidase