title: alpha-Amylase from developing embryos of the camel tick Hyalomma dromedarii.
abstract: alpha-Amylase activity in the camel tick Hyalomma dromedarii was followed throughout embryogenesis. During purification of alpha-amylase III to homogeneity, ion exchange chromatography lead to four separate forms (termed I, II, III and IV). alpha-Amylase III with the highest specific activity was pure after chromatography on Sephacryl S-300. The molecular mass of alpha-amylase III was 106 kDa for the native enzyme, composed of two subunits of 43 and 66 kDa, respectively. alpha-Amylase had a value of 10 mg starch/ml. Varying alpha-amylase activity was detected when supplied with various substrates. alpha-Amylase III had a temperature optimum at 40 degrees C with heat stability up to 50 degrees C, and a pH optimum of 7.0. The enzyme activity was activated by CaCl2, MgCl2 and NaNO3, but not activated by NaCl, p-CMB, N-ethylmaleimide and iodoacetamide. EDTA and beta-mercaptoethanol strongly inhibited activity.
authors.affiliation: Molecular Biology Department, National Research Centre, Dokki, Cairo, Egypt.
authors.forename: S A
authors.initials: SA
authors.lastname: Mohamed
mesh_terms: D000818:Animals; D005260:Female; D008970:Molecular Weight; D010063:Ovum / Q000201:enzymology; D013987:Ticks / Q000196:embryology / Q000201:enzymology*; D000516:alpha-Amylases / Q000302:isolation & purification / Q000378:metabolism*
chemical_list: D000516:alpha-Amylases