Characterization of 6-hexadecanoylamino-4-methylumbelliferyl-beta-D- galactopyranoside as fluorogenic substrate of galactocerebrosidase for the diagnosis of Krabbe disease

Clin Chim Acta. 1992 Jan 31;205(1-2):87-96. doi: 10.1016/s0009-8981(05)80003-8.


6-Hexadecanoylamino-4-methylumbelliferyl-beta-D-galactopyranoside (HMGal) has been shown to be a specific fluorogenic substrate of galactocerebrosidase and to facilitate the simple enzymatic diagnosis of Krabbe disease in human patients and in twitcher mice. HMGal hydrolysis at pH 4.5 is optimally stimulated by sodium taurocholate (0.25%) and oleic acid (0.05%) with a Km of 0.150, 0.04 and 0.03 mM, respectively for control mouse kidney, human fibroblasts and leukocytes. In control samples, the specific activity (nmol/mg prot./h) for HMGal is higher than for the natural substrate, galactocerebroside, and is severely deficient in the twitcher mouse and in patients with Krabbe disease. Comparative investigation of galactocerebrosidase activity in fibroblasts, leukocytes and brain with radioactive and fluorogenic substrates reveals a good agreement between the results of the two methods. Galactocerebroside (Gal-Cer) is a competitive inhibitor of HMGal hydrolysis in mouse kidney homogenates while GM1-ganglioside has no inhibitory effect in the same assay system. The sensitivity and specificity of this fluorogenic substrate for galactocerebrosidase provides a simple and rapid method for the diagnosis of Krabbe disease, and for the purification of this enzyme from normal tissues.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Brain / enzymology
  • Carbohydrate Sequence
  • Cells, Cultured
  • Clinical Enzyme Tests*
  • Dose-Response Relationship, Drug
  • Female
  • Fibroblasts / cytology
  • Fibroblasts / enzymology
  • Fluorescent Dyes
  • Galactosides / chemistry*
  • Galactosides / metabolism
  • Galactosylceramidase / metabolism*
  • Galactosylceramides / metabolism
  • Humans
  • Hydrolysis
  • Hymecromone / analogs & derivatives*
  • Hymecromone / chemistry
  • Hymecromone / metabolism
  • Leukocytes / enzymology
  • Leukodystrophy, Globoid Cell / diagnosis*
  • Leukodystrophy, Globoid Cell / enzymology
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Molecular Sequence Data
  • Oleic Acid
  • Oleic Acids / pharmacology
  • Substrate Specificity
  • Taurocholic Acid / pharmacology


  • Fluorescent Dyes
  • Galactosides
  • Galactosylceramides
  • Oleic Acids
  • galactocerebroside
  • Oleic Acid
  • Hymecromone
  • Taurocholic Acid
  • 6-hexadecanoylamino-4-methylumbelliferyl-galactopyranoside
  • Galactosylceramidase