TY - JOUR
T1 - Enhanced thermal stability of lysosomal β-D-galactosidase in parenchymal cells of tumour bearing mice
AU - Lenti, L.
AU - Lipari, M.
AU - Lombardi, D.
AU - Zicari, A.
AU - Dotta, A.
AU - Pontieri, G. M.
PY - 1986
Y1 - 1986
N2 - The thermal stability of the enzyme β-D-galactosidase varies among different organs in normal C57Bl/6 mice, and increases in the same organs in mice with Lewis Lung carcinoma. Thermal stability of this enzyme is also increased by treatment of the mice with cell-free extracts of tumour cells or with inflammatory compounds such as carrageenan or orosomucoid. After desialylation, orosomucoid more effectively increases the heat stability of the enzyme. By contrast talc, which has no galactosyl groups, is without effect on the stability of the enzyme in vivo. Macrophages of tumour bearing mice release into the culture medium a more heat resistant enzyme than macrophages from control mice. In both cases the heat resistance of the secreted enzyme is higher when fetal calf serum is present in the culture medium. Bovine serum does not modify the thermal stability of β-D-galactosidase in this system. Incubation of lysosomal fractions of various organs with the synthetic β-D-galactosidase substrate, p-nitrophenyl-galactopyranoside, also strongly increases the heat resistance of the enzyme. The results suggest that one factor influencing the heat resistance of this enzyme may be complex formation between the enzyme and its substrates, an example of substrate protection of the enzyme. This may not be the only factor involved in enzyme stabilization in vivo.
AB - The thermal stability of the enzyme β-D-galactosidase varies among different organs in normal C57Bl/6 mice, and increases in the same organs in mice with Lewis Lung carcinoma. Thermal stability of this enzyme is also increased by treatment of the mice with cell-free extracts of tumour cells or with inflammatory compounds such as carrageenan or orosomucoid. After desialylation, orosomucoid more effectively increases the heat stability of the enzyme. By contrast talc, which has no galactosyl groups, is without effect on the stability of the enzyme in vivo. Macrophages of tumour bearing mice release into the culture medium a more heat resistant enzyme than macrophages from control mice. In both cases the heat resistance of the secreted enzyme is higher when fetal calf serum is present in the culture medium. Bovine serum does not modify the thermal stability of β-D-galactosidase in this system. Incubation of lysosomal fractions of various organs with the synthetic β-D-galactosidase substrate, p-nitrophenyl-galactopyranoside, also strongly increases the heat resistance of the enzyme. The results suggest that one factor influencing the heat resistance of this enzyme may be complex formation between the enzyme and its substrates, an example of substrate protection of the enzyme. This may not be the only factor involved in enzyme stabilization in vivo.
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M3 - Article
C2 - 3099822
AN - SCOPUS:0022973720
VL - 67
SP - 793
EP - 799
JO - British Journal of Experimental Pathology
JF - British Journal of Experimental Pathology
SN - 0007-1021
IS - 6
ER -