ANALYSIS OF GLUCOCEREBROSIDASE ACTIVITY USING N-(1-[C-14]HEXANOYL)-D-ERYTHRO-GLUCOSYLSPHINGOSINE DEMONSTRATES A CORRELATION BETWEEN LEVELS OF RESIDUAL ENZYME-ACTIVITY AND THE TYPE OF GAUCHER DISEASE
I. Meivarlevy et al., ANALYSIS OF GLUCOCEREBROSIDASE ACTIVITY USING N-(1-[C-14]HEXANOYL)-D-ERYTHRO-GLUCOSYLSPHINGOSINE DEMONSTRATES A CORRELATION BETWEEN LEVELS OF RESIDUAL ENZYME-ACTIVITY AND THE TYPE OF GAUCHER DISEASE, Biochemical journal, 303, 1994, pp. 377-382
Glucosylceramide, a degradation product of complex glycosphingolipids,
is hydrolysed in lysosomes by glucocerebrosidase (GlcCerase). Mutatio
ns in the human GlcCerase gene cause a reduction in GlcCerase activity
and accumulation of glucosylceramide, which results in the onset of G
aucher disease, the most common lysosomal storage disease. Significant
clinical heterogeneity is observed in Gaucher disease, with three mai
n types known, but no clear correlation has been reported between the
different types and levels of residual GlcCerase activity. We now demo
nstrate that a correlation exists by using a radioactive, short-acyl c
hain substrate, N-(1-[C-14]hexanoyl)-D-erythro-glucosylsphingosine ([C
-14]hexanoyl-GlcCer). This substrate rapidly transferred into biologic
al membranes in the absence of detergent [Futerman and Pagano (1991) B
iochem. J. 280, 295-302] and was hydrolyzed to N-(1-[C-14]hexanoyl)-D-
erythro-sphingosine ([C-14]hexanoyl-Cer) both in vitro and in situ, wi
th an acid pH optimum. A strict correlation was observed between level
s of [C-14]hexanoyl-GlcCer hydrolysis and Gaucher type in human skin f
ibroblasts. The mean residual activity measured in vitro for 3 h incub
ation in type 1 Gaucher fibroblasts (the mild form of the disease) was
46.3 +/- 4.6 nmol of [C-14]hexanoyl-Cer formed per mg protein (n = 9)
, and in type 2 and 3 fibroblasts (the neuronopathic forms of the dise
ase) was 19.6 +/- 6.5 (n = 9). A similar correlation was observed when
activity was measured in situ, suggesting that the clinical severity
of a lysosomal storage disease is related to levels of residual enzyme
activity.