title: Digestive alpha-amylases from Tecia solanivora larvae (Lepidoptera: Gelechiidae): response to pH, temperature and plant amylase inhibitors.
abstract: The biochemical properties of the digestive alpha-amylase from Tecia solanivora larvae, an important and invasive insect pest of potato (Solanum tuberosum), were studied. This insect has three major digestive alpha-amylases with isoelectric points 5.30, 5.70 and 5.98, respectively, which were separated using native and isoelectric focusing gels. The alpha-amylase activity has an optimum pH between 7.0 and 10.0 with a peak at pH 9.0. The enzymes are stable when heated to 50 degrees C and were inhibited by proteinaceous inhibitors from Phaseolus coccineus (70% inhibition) and P. vulgaris cv. Radical (87% inhibition) at pH 6.0. The inhibitors present in an amaranth hybrid inhibited 80% of the activity at pH 9.0. The results show that the alpha-amylase inhibitor from amaranth seeds may be a better candidate to make genetically-modified potatoes resistant to this insect than inhibitors from common bean seeds.
authors.affiliation: Embrapa Recursos Genéticos e Biotecnologia, PqEB, W5 Norte Final, Brasília - DF, 70770-900, Brasil.
authors.forename: A
authors.initials: A
authors.lastname: Valencia-Jiménez
authors.forename: J W
authors.initials: JW
authors.lastname: Arboleda
authors.forename: A
authors.initials: A
authors.lastname: López Avila
authors.forename: M F
authors.initials: MF
authors.lastname: Grossi-de-Sá
mesh_terms: D000818:Animals; D004791:Enzyme Inhibitors / Q000737:chemistry*; D004795:Enzyme Stability; D006863:Hydrogen-Ion Concentration; D007814:Larva / Q000201:enzymology; D009036:Moths / Q000201:enzymology* / Q000254:growth & development; D010940:Plant Proteins / Q000737:chemistry*; D013696:Temperature; D000516:alpha-Amylases / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000502:physiology
chemical_list: D004791:Enzyme Inhibitors; D010940:Plant Proteins; D000516:alpha-Amylases