Invertase Inhibitors from Sweet Potato (Ipomoea batatas):  Purification and Biochemical Characterization

• Published in: Journal of agricultural and food chemistry Vol. 51; no. 16; pp. 4804 - 4809
• Main Authors: Wang, Yung-Liang, Wu, Chang-Yi, Chang, Chen-Tien, Sung, Hsien-Yi
• Format: Journal Article
• Language: English; Russian
• Published: United States American Chemical Society 30.07.2003
• Subjects: acetone; acid treatment; affinity chromatography; Amino Acid Sequence; beta-fructofuranosidase; beta-Fructofuranosidase - antagonists & inhibitors; Enzyme Inhibitors - chemistry; Enzyme Inhibitors - isolation & purification; Enzyme Inhibitors - pharmacology; filtration; Hydrogen-Ion Concentration; ion exchange chromatography; Ipomoea batatas; Ipomoea batatas - chemistry; leaves; Molecular Weight; Peptide Fragments - chemistry; Plant Leaves - chemistry; Plant Roots - chemistry; polyacrylamide gel electrophoresis; roots; sweet potatoes; thermal stability; Western blotting
• ISSN: 0021-8561; 1520-5118
• DOI: 10.1021/jf026107i

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 °C for 20 min), and Western blotting showed them to be immunologically related. Keywords: Sweet potato invertase inhibitor; purification; properties