ISSN:
0739-4462
Keywords:
Sitophilus
;
S. oryzae
;
S. granarius
;
S. zeamais
;
rice weevil
;
granary weevil
;
maize weevil
;
amylase
;
purification
;
digestion
;
cereals
;
feeding
;
amylase inhibitors
;
adaptive significance
;
Chemistry
;
Food Science, Agricultural, Medicinal and Pharmaceutical Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Biology
Notes:
Amylases from adults of Sitophilus oryzae (L.) and S. granarius (L.) were purified by using a sequential procedure of ammonium sulfate precipitation, glycogen-complex formation, and ion exchange chromatography. Amylase of S. oryaze was purified 47.4-fold to a specific activity of 478 units/mg protein. One amylase unit equals 1 mg maltose hydrate produced/min at 30°C. Amylase of S. granarius was purified 85.4-fold to a specific activity of 453 units/mg protein. Amylase of S. oryzae had a Km of 0.173% for soluble starch and consisted of two anionic isozyrnes with isoelectric points of pH 3.70 and pH 3.76. Amylase of S. granarius had a Km of 0.078% for starch and was a single protein with an isoelectric point of pH 3.76. Purified amylases of both species had molecular weights of 56,000 estimated by sodium dodecyl sulfatepolyacrylamide gel electrophoresis, were activated by chloride, and had double energies of activation calculated from Arrhenius plots. Based on fresh weights of adults feeding on whole wheat through 10 weeks of age, S. oryzae contained three-fold and eight-fold more amylase than S. granarius and S. zeamais Motschulsky, respectively. High amylase levels in S. oryzae may provide this species with an adaptive advantage when feeding on cereals containing naturally occurring amylase inhibitors.
Additional Material:
5 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/arch.940020409
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