The 50-kDa glucose 6-phosphate-sensitive hexokinase of Schistosoma mansoni.

摘要: Hexokinase has been purified from adult Schistosoma mansoni worms and the activity shown to be associated with a single protein species having an M(r) about 50,000. This is recognized on Western blots probed antisera against rat Type I hexokinase or recombinant S. that had expressed in Escherichia coli using previously cloned cDNA. An 18-residue N-terminal sequence determined for identical deduced nucleotide of cDNA, consistent view cDNA encodes characterized present study. The enzyme relatively low Km (approximately 60 microM) glucose sensitive inhibition (competitive versus ATP, Ki approximately 50 by its product, 6-phosphate (Glc-6-P). With these kinetic properties kDa molecular mass, resembles ancestral predicted have given rise, gene duplication fusion, day 100-kDa Glc-6-P-sensitive mammalian hexokinases. schistosomal represents first 50-kDa whose obtained. does not bind mitochondria, lack hydrophobic segment at N terminus which required binding II isoenzymes mitochondria. marked Crabtree effect exhibited cercariae may least partly attributed expression rather high levels affinity but only moderate sensitivity product Glc-6-P.