NEW PATHWAY OF HEPARAN-SULFATE DEGRADATION IDURONATE SULFATASE AND N-SULPHOGLUCOSAMINE 6-SULFATASE ACT ON THE POLYMER-CHAIN PRIOR TO DEPOLYMERIZATION BY A N-SULFO-GLUCOSAMINIDASE AND GLYCURONIDASES IN THE MOLLUSK TAGELUS-GIBBUS
Mgl. Medeiros et al., NEW PATHWAY OF HEPARAN-SULFATE DEGRADATION IDURONATE SULFATASE AND N-SULPHOGLUCOSAMINE 6-SULFATASE ACT ON THE POLYMER-CHAIN PRIOR TO DEPOLYMERIZATION BY A N-SULFO-GLUCOSAMINIDASE AND GLYCURONIDASES IN THE MOLLUSK TAGELUS-GIBBUS, Comparative biochemistry and physiology. B. Comparative biochemistry, 119(3), 1998, pp. 539-547
It has previously been shown that in the mollusc Anomalocardia brasili
ana the desulphation of chondroitin sulphate precedes its depolymerisa
tion by beta-glucuronidase and beta-N-acetylgalactosaminidase (Sousa J
r. et al. J. Biol. Chem. 1990;265:20150-20155). This led us to investi
gate whether in molluscs, sulphatases also act on heparan sulphate bef
ore its depolymerisation by glycosidases. Radioactively labelled [S-35
]heparan sulphate was extensively degraded by enzyme extracts prepared
from the mollusc Tagelus gibbus. Several enzymes acting in concert de
grade the compound to inorganic sulphate, glucosamine N-sulphate, N-ac
etylglucosamine-6 sulphate and other oligosaccharide products. These r
esults indicate the presence of iduronate sulphatase, N-sulphoglucosam
ine 6-sulphatase alpha-N-sulphoglucosaminidase, beta-glucuronidase and
alpha-L-iduronidase. The di- and mono-saccharide composition of the o
ligosaccharides were analysed with the aid of heparitinase II from Fla
vobacterium, heparimum. These analyses led to the characterisation of
two sulphatases that act on the polymer chain removing sulphates from
the C-2 position of iduronic acid residues and the C-6 position of the
glucosamine moieties, respectively. The different enzymes were partia
lly fractionated by ion exchange chromatography and molecular sieving.
These results led to the proposition of a new pathway of degradation
of heparan sulphate where sulphatases act directly on the polymer chai
n which is then depolymerised by several glycosidases. (C) 1998 Elsevi
er Science Inc. All rights reserved.