Characterization of alpha-mannosidase in feline mannosidosis. 1988

S Raghavan, and G Stuer, and L Riviere, and J Alroy, and E H Kolodny
Department of Biochemistry, Eunice Kennedy Shriver Center for Mental Retardation, Inc., Waltham, MA 02254.

Acidic alpha-mannosidase deficiency has been identified in a family of Blue Persian cats. Characterization of the residual activity revealed that the Km for the substrate, 4-methylumbelliferyl-alpha-D-mannoside, increased approximately three-fold with a severe deficiency in Vmax (1-2%) in homogenates of liver and brain of affected cats compared with controls. The residual activity at pH 4.0 in liver homogenates from affected cats is very thermolabile at 51 degrees C while the control activity is stable at this temperature for 1 h. Subcellular fractionation of liver was performed from a control and diseased cat in order to compare the properties of the different alpha-mannosidases localized in these fractions. The residual activity present in the lysosomal fraction from diseased cat liver showed altered pH optimum, two-fold increase in Km with a severely reduced Vmax and increased thermolability compared with the activity in the lysosomal fraction from control liver. The thermal inactivation pattern and Km of the residual activity in the lysosomal fraction is different from the non-lysosomal alpha-mannosidase in the liver of the affected cat. This suggests that the residual activity in the lysosomal fraction of the liver from the affected cat is not due to contamination of non-lysosomal alpha-mannosidase in this fraction. Whether this residual activity represents the properties of the mutant enzyme or yet another minor normal component of lysosomes different from the major inactive mutant or absent lysosomal enzyme remains to be elucidated.

UI MeSH Term Description Entries
D008099 Liver A large lobed glandular organ in the abdomen of vertebrates that is responsible for detoxification, metabolism, synthesis and storage of various substances. Livers
D008361 Mannosidases Glycoside hydrolases that catalyze the hydrolysis of alpha or beta linked MANNOSE. Mannosidase
D008363 alpha-Mannosidosis An inborn error of metabolism marked by a defect in the lysosomal isoform of ALPHA-MANNOSIDASE activity that results in lysosomal accumulation of mannose-rich intermediate metabolites. Virtually all patients have psychomotor retardation, facial coarsening, and some degree of dysostosis multiplex. It is thought to be an autosomal recessive disorder. Mannosidosis, alpha B, Lysosomal,Alpha-D-Mannosidosis,Alpha-Mannosidase B Deficiency,Alpha-Mannosidosis, Type I,Lysosomal Alpha B Mannosidosis,Lysosomal alpha-D-Mannosidase Deficiency,Mannosidosis, alpha B Lysosomal,alpha Mannosidase B Deficiency,alpha-Mannosidase Deficiency,Deficiencies, Lysosomal alpha-D-Mannosidase,Deficiencies, alpha-Mannosidase,Deficiency, Lysosomal alpha-D-Mannosidase,Deficiency, alpha-Mannosidase,Lysosomal alpha D Mannosidase Deficiency,Lysosomal alpha-D-Mannosidase Deficiencies,alpha Mannosidase Deficiency,alpha Mannosidosis,alpha-D-Mannosidase Deficiencies, Lysosomal,alpha-D-Mannosidase Deficiency, Lysosomal,alpha-Mannosidase Deficiencies,alpha-Mannosidoses
D009154 Mutation Any detectable and heritable change in the genetic material that causes a change in the GENOTYPE and which is transmitted to daughter cells and to succeeding generations. Mutations
D001921 Brain The part of CENTRAL NERVOUS SYSTEM that is contained within the skull (CRANIUM). Arising from the NEURAL TUBE, the embryonic brain is comprised of three major parts including PROSENCEPHALON (the forebrain); MESENCEPHALON (the midbrain); and RHOMBENCEPHALON (the hindbrain). The developed brain consists of CEREBRUM; CEREBELLUM; and other structures in the BRAIN STEM. Encephalon
D002371 Cat Diseases Diseases of the domestic cat (Felis catus or F. domesticus). This term does not include diseases of the so-called big cats such as CHEETAHS; LIONS; tigers, cougars, panthers, leopards, and other Felidae for which the heading CARNIVORA is used. Feline Diseases,Cat Disease,Disease, Cat,Disease, Feline,Diseases, Cat,Diseases, Feline,Feline Disease
D002415 Cats The domestic cat, Felis catus, of the carnivore family FELIDAE, comprising over 30 different breeds. The domestic cat is descended primarily from the wild cat of Africa and extreme southwestern Asia. Though probably present in towns in Palestine as long ago as 7000 years, actual domestication occurred in Egypt about 4000 years ago. (From Walker's Mammals of the World, 6th ed, p801) Felis catus,Felis domesticus,Domestic Cats,Felis domestica,Felis sylvestris catus,Cat,Cat, Domestic,Cats, Domestic,Domestic Cat
D000818 Animals Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA. Animal,Metazoa,Animalia
D043323 alpha-Mannosidase An enzyme that catalyzes the HYDROLYSIS of terminal, non-reducing alpha-D-mannose residues in alpha-D-mannosides. The enzyme plays a role in the processing of newly formed N-glycans and in degradation of mature GLYCOPROTEINS. There are multiple isoforms of alpha-mannosidase, each having its own specific cellular location and pH optimum. Defects in the lysosomal form of the enzyme results in a buildup of mannoside intermediate metabolites and the disease ALPHA-MANNOSIDOSIS. Lysosomal alpha-Mannosidase,LAMAN,Neutral alpha-Mannosidase,alpha Mannosidase B,alpha-D-Mannosidase,alpha-D-Mannoside Mannohydrolase,Lysosomal alpha Mannosidase,Mannohydrolase, alpha-D-Mannoside,Mannosidase B, alpha,Neutral alpha Mannosidase,alpha D Mannosidase,alpha D Mannoside Mannohydrolase,alpha Mannosidase,alpha-Mannosidase, Lysosomal,alpha-Mannosidase, Neutral

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