Salivary alpha-glucosidases (Mali) have been much less characterized when compared with midgut alpha-glucosidases, which have been studied in depth. Few studies have been reported on the partial characterization of Mall, but no clear function has been ascribed. The aim of this study is to purify and characterize the recombinant Culex quinquefasciatus (CQ) alpha-glucosidase expressed in Pichia pastoris. The cDNA encoding mature Cx. quinquefasciatus alpha-glucosidase gene with polyhistidine tag (rCQMaIIHis) was successfully cloned into the expression vector, pPICZ alpha B, designated as pPICZ alpha beta/ CQMallHis. The activity of recombinant rCQMaIIHis expressed in P. pastoris could be detected at 3.75 U/ml, under optimal culture conditions. The purified rCQMaIIHis showed a single band of molecular weight of approximately 92 kDa on SDS-PAGE. After Endoglycosidase H digestion, a single band at 69 kDa was found on SDS-PAGE analysis, suggesting that rCQMaIIHis is a glycoprotein. Additionally, tryptic digestion and LC-MALDI MS/MS analysis suggested that the 69 kDa band corresponds to the Cx. quinquefasciatus alpha-glucosidase. Thus, rCQMaIIHis is a glycoprotein. The rCQMaIIHis exhibited optimum pH and temperature at 5.5 and 35 degrees C, respectively. The catalytic efficiency (k(cat)/K-m) of the purified rCQMalIHis for maltotriose is higher than those for sucrose, maltotetraose, maltose and p-nitrophenyl-cc-glucoside, indicating that the enzyme prefers maltotriose. Additionally, the rCQMalIHis is significantly inhibited by D-gluconic acid delta-lactone, but not by me, Ca2+ and EDTA. The rCQMaIIHis is strongly inhibited by acarbose with IC50 67.8 +/- 5.6 nM, but weakly inhibited by glucose with IC50 115.9 +/- 7.3 mM. (C) 2015 Elsevier Inc. All rights reserved.