title: N-acetylglucosamine kinase and N-acetylglucosamine 6-phosphate deacetylase in normal human erythrocytes and Plasmodium falciparum.
abstract: The major pathways of glucose metabolism in the malaria parasite, Plasmodium falciparum, have now been elucidated, and the structures and properties of parasite-specific enzymes are presently being investigated. Little is known, however, about the enzymes catalysing monosaccharide interconversions in the parasite. In the present investigation we have examined the pathway of N-acetylglucosamine catabolism which, in higher organisms, involves the following reaction sequence: N-acetylglucosamine -->N-acetylglucosamine 6-phosphate-->glucosamine 6-phosphate-->fructose 6-phosphate. Assay of the specific kinase (E.C. 2.7.1.59) catalysing the phosphorylation of the sugar showed that the enzyme is present in Plasmodium extracts as well as in normal human erythrocytes; specific activities of 7.2 and 5.3 nmol/h/mg protein were measured for the parasite and erythrocyte extracts, respectively, N-Acetylglucosamine 6-phosphate deacetylase (E.C. 3.5.1.25), catalysing the second reaction, was also detected in both normal and Plasmodium-infected erythrocytes. At 75% parasitaemia, the deacetylase activity was close to 3 times higher than that of normal control cells. The erythrocyte deacetylase was purified approximately 16,000-fold by chromatography on DE52 cellulose, chromatofocusing, and size exclusion chromatography. Attempts to purify the parasite enzyme by the same procedures were unsuccessful due to loss of activity. A partially purified erythrocyte deacetylase preparation (eluted from DE52 cellulose) had a pH optimum of 7.5, a pI of 6.0, as indicated by chromatofocusing, and a K(m) of 29 microM. In conjunction with previous investigations, the present study indicated that all three enzymes required for N-acetylglucosamine utilization are present in Plasmodium parasites as well as in normal erythrocytes.
authors.affiliation: Department of Microbiology, University of Alabama at Birmingham 35294-2170, USA.
authors.forename: J A
authors.initials: JA
authors.lastname: Weidanz
authors.forename: P
authors.initials: P
authors.lastname: Campbell
authors.forename: D
authors.initials: D
authors.lastname: Moore
authors.forename: L J
authors.initials: LJ
authors.lastname: DeLucas
authors.forename: L
authors.initials: L
authors.lastname: Rodén
authors.forename: J N
authors.initials: JN
authors.lastname: Thompson
authors.forename: A C
authors.initials: AC
authors.lastname: Vezza
mesh_terms: D000581:Amidohydrolases / Q000378:metabolism*; D000818:Animals; D002851:Chromatography, High Pressure Liquid; D004912:Erythrocytes / Q000201:enzymology* / Q000469:parasitology; D006801:Humans; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000378:metabolism*; D010963:Plasmodium falciparum / Q000201:enzymology*; D001619:beta-N-Acetylhexosaminidases / Q000378:metabolism*
chemical_list: D017853:Phosphotransferases (Alcohol Group Acceptor); C018716:N-acetylglucosamine kinase; D001619:beta-N-Acetylhexosaminidases; D000581:Amidohydrolases; C018717:N-acetylglucosamine-6-phosphate deacetylase