Alkaline Phosphatases From Camel Small Intestine

Abstract

Camel intestinal alkaline phosphatase have been purified and characterized. The purification was carried out by chromatography on DEAE-cellulose. Five intestinal alkaline phosphatase isoenzymes (IAP1 to IAP5) were obtained. IAP2 and IAP5 with the highest activity levels were purified to homogeneity by Sephacryl S-200 column. The molecular weights of camel small intestinal IAP2 and IAP5 were estimated to be 36,000 Da and 49,800 Da, respectively using Sephacryl S-200. These values were confirmed by SDS-PAGE, where the two enzymes migrated on the gel as single subunits and the molecular weights were 35,000 Da and 49,000 Da, respectively. IAP2 and IAP5 had isoelectric points at 5.4 and 5.7 and Km values of IAP2 and IAP5 are 0.26 and 0.34 mol p-nitrophenyl phosphate/ml, respectively. The two alkaline phosphatases IAP2 and IAP5 were found to have common character that they had higher affinity toward p-nitrophenyl phosphatae and α-naphthyl phosphate compared to the other studied substrates. IAP2 and IAP5 had pH optima at 10 and 10.5 and temperature optima at 50ºC and 40ºC with activation energy 9.3 and 9.6 Kcal mol-1, respectively. The two isoenzymes were stable up to 40ºC and 50ºC, respectively. The effect of different metal cations on the activity of camel intestinal IAP2 and IAP5 was studied. The camel intestinal alkaline phosphatase isoenzymes IAP2 and IAP5 were inhibited by EDTA and phenylalanine.

Keywords: Camel; Small intestine; Alkaline phosphatase ; Purification; Characterization

Egyptian Journal of Biochemistry and Molecular Biology Vol. 26 (1) 2008 pp. 31-54