Alkaline phosphatases of the mosquito, Culex tarsalis Coquillett.
Spectrophotometric and isoelectric focusing (IEF) electrophoretic characterization of the alkaline phosphatase (ALKP) of the mosquito, Culex tarsalis, are presented. With p-nitrophenylphosphate (Pnp) as substrate, ALKP was optimally active at 37 degrees C, pH 8.0, 30 mM MgCl2, Vmax was 35.8 mumoles/10 min and the Km was 5.7 mM, with no demonstrable requirement for Zn2+. The spectrophotometric enzyme(s) was stimulated by dithiothreitol, 2-mercaptoethanol, and poly-vinylpyrollidone (PVP); inhibited by NaF, several alternative cations (Ca2+, Ba2+, Fe2+, Cu2+), and EDTA. ALKP activity was cyclic during the 15 day post-adult emergence period of the study. No significant differences were noted between the specific activities of males and females. IEF electrophoresis revealed 6 ALKP isozymes detected with alpha-naphthylphosphate within the pH range 4.0-5.5, with a second group of 3 rather indistinct species in the pH 6.0-7.0 range. IEF ALKP isozymes were stimulated by Mg2+ and PVP and inhibited by EDTA (except ALKP5.0) and cysteine; partial inhibition with phenylalanine. IEF detection of ALKP activity with Pnp indicated that the majority of the activity was localized in the pH 4.0-5.5 range, in close agreement with the alpha-naphthylphosphate results.
D000469:Alkaline Phosphatase / Q000032:analysis* / Q000037:antagonists & inhibitors; D000818:Animals; D003465:Culex / Q000201:enzymology*; D006863:Hydrogen-Ion Concentration; D007526:Isoelectric Point; D007527:Isoenzymes / Q000032:analysis; D007700:Kinetics; D008274:Magnesium / Q000494:pharmacology; D009596:Nitrophenols / Q000378:metabolism; D009943:Organophosphorus Compounds / Q000378:metabolism; D012995:Solubility; D013696:Temperature
D007527:Isoenzymes; D009596:Nitrophenols; D009943:Organophosphorus Compounds; C008644:nitrophenylphosphate; D000469:Alkaline Phosphatase; D008274:Magnesium