title: Thermodynamic characterisation of the mutated isoenzyme A of beta-N-acetylhexosaminidase in GM2-gangliosidosis B1 variant.
abstract: Here we report the determination of the activation energies of the plasma isoenzymes of beta-N-acetylhexosaminidase (Hex, EC 3.2.1.52), isolated by chromatography in DEAE-cellulose, using the neutral chromogenic substrate 3,3'dichlorophenylsulfonphthaleinyl-N-acetyl-beta-D-glucosaminide. The activation energy of mutated Hex A isoenzyme (Ea approximately 71.5 kJ/mol) from a patient with GM2-gangliosidosis B1 variant, homozygote for the G533-->A (Arg178His) mutation, was significantly higher than that of normal Hex A (Ea approximately 41.8 kJ/mol) and analogous to that of Hex B isoenzyme (Ea approximately 75.1 kJ/mol). The determination of this thermodynamic variable of Hex in different biological specimens could allow for a straightforward biochemical characterisation of the GM2-gangliosidosis B1 variant.
authors.affiliation: Laboratorio Central, Hospital General de Galicia-Clinico Universitario, Santiago de Compostela, Spain.
authors.forename: L F
authors.initials: LF
authors.lastname: Pérez
authors.forename: H M
authors.initials: HM
authors.lastname: Ribeiro
authors.forename: J A
authors.initials: JA
authors.lastname: Casal
authors.forename: R A
authors.initials: RA
authors.lastname: Pinto
authors.forename: M C
authors.initials: MC
authors.lastname: Sá Miranda
authors.forename: J C
authors.initials: JC
authors.lastname: Tutor
mesh_terms: D002648:Child; D002848:Chromatography, DEAE-Cellulose; D005260:Female; D005733:Gangliosidoses / Q000201:enzymology* / Q000235:genetics; D054818:Hexosaminidase A; D054819:Hexosaminidase B; D006720:Homozygote; D006801:Humans; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism*; D017354:Point Mutation; D013816:Thermodynamics; D001619:beta-N-Acetylhexosaminidases / Q000235:genetics / Q000378:metabolism*
chemical_list: D007527:Isoenzymes; D054818:Hexosaminidase A; D054819:Hexosaminidase B; D001619:beta-N-Acetylhexosaminidases