title: A molecular and biochemical analysis of the structure of the cyanogenic beta-glucosidase (linamarase) from cassava (Manihot esculenta Cranz).
abstract: The cyanogenic beta-glucosidase (linamarase) of cassava is responsible for the first step in the sequential break-down of two related cyanoglucosides. Hydrolysis of these cyanoglucosides occurs following tissue damage and leads to the production of hydrocyanic acid. This mechanism is widely regarded as a defense mechanism against predation. A linamarase cDNA clone (pCAS5) was isolated from a cotyledon cDNA library using a white clover beta-glucosidase heterologous probe. The nucleotide and derived amino acid sequence is reported and five putative N-asparagine glycosylation sites are identified. Concanavalin A affinity chromatography and endoglycosidase H digestion demonstrate that linamarase from cassava is glycosylated, having high-mannose-type N-asparagine-linked oligosaccharides. Consistent with this structure and the extracellular location of the active enzyme is the identification of an N-terminal signal peptide on the deduced amino acid sequence of pCAS5.
authors.affiliation: Department of Biochemistry and Genetics, The University, Newcastle upon Tyne, United Kingdom.
authors.forename: M A
authors.initials: MA
authors.lastname: Hughes
authors.forename: K
authors.initials: K
authors.lastname: Brown
authors.forename: A
authors.initials: A
authors.lastname: Pancoro
authors.forename: B S
authors.initials: BS
authors.lastname: Murray
authors.forename: E
authors.initials: E
authors.lastname: Oxtoby
authors.forename: J
authors.initials: J
authors.lastname: Hughes
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D002846:Chromatography, Affinity; D003001:Cloning, Molecular; D004247:DNA / Q000235:genetics; D004591:Electrophoresis, Polyacrylamide Gel; D006031:Glycosylation; D006596:Hexosaminidases; D007700:Kinetics; D002365:Manihot / Q000201:enzymology*; D008969:Molecular Sequence Data; D012689:Sequence Homology, Nucleic Acid; D001617:beta-Glucosidase / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism
chemical_list: D004247:DNA; D006596:Hexosaminidases; C021514:cyanogenic beta-glucosidase; D001617:beta-Glucosidase