469
Clinica
Chimica
Aata,
89 (1978)
@ Elsevier/North-Holland
469-473 Biomedical Press
CGA 9795
LYSOSOMAL
HYDROLASES
IN CYSTIC FIBROSIS
LIVERS
JACK A. ALHADEFF Department of Neurosciences, La Jolla, Calif. 92093 (U.S.A.)
(Received
School
of Medicine,
University
of California,
San Diego,
June 7th, 1978)
Summary The specific activity of several lysosomal hydrolases in normal and cystic fibrosis (CF) livers has been investigated. Neuraminidase activity with respect to two natural substrates (fetuin and bovine submaxillary mucin) is normal in CF livers. No significant differences were found between CF and normal livers in 4-methylumbelliferyl-cu-D-mannosidase specific activities determined at three different pH values (4.3, 5.65 and 6.5) corresponding to lysosomal, golgi and cytosolic components of the enzyme, respectively. The specific activities of p-nitrophenyl-fl-D-mannosidase and 4-methylumbelliferyl-P_N-acetylglucosaminidase were also both similar in CF and normal livers.
Introduction Cystic fibrosis (CF) is one of the most common genetic diseases among Caucasian children and manifests itself as a generalized disorder primarily affecting exocrine glands and the pulmonary and gastrointestinal systems [ 1,2]. The fact that CF is transmitted as an autosomal recessive trait [ 31 suggests that the primary biochemical defect involves alteration or lack of a gene product. To date, no one has determined the basic defect in this important disease. Several biochemical studies have been done on lysosomal hydrolases in CF tissues (see rev. ref. 1) but no consistent findings have been found which point to the biochemical defect in this fatal disease. In the present investigation the activities of neuraminidase, fl-D-mannosidase, a-D-mannosidase and fl-N-acetylglucosaminidase in normal and CF livers have been studied. These particular enzymes were chosen for study because of our recent findings of decreased amounts of sialic acid, mannose and iV-acetylglucosamine in the glycoprotein a-L-fucosidase purified from two different CF livers [4]. These altered cY-L-fucosidase carbohydrate compositions could arise from aberrant glycoprotein biosynthesis and/or degradation in cystic fibrosis patients. This study
470
on degradative enzymes is the first report on CF tissues which investigates (1) neuraminidase activity using natural substrates (fetuin and bovine submaxillary mucin), (2) ~-m~nosid~e activity and (3) the activity of the various ar-mannosidases (lysosomal, golgi and cytosolic [ 5,6] ). Previous studies on cu-mannosidase activity in CF tissues [7-91 have not looked at the different forms of this enzyme. Materials and methods General
All procedures were carried out at 0-4°C unless otherwise stated. Protein was determined
Clinica
Chimica
Aata,
89 (1978)
@ Elsevier/North-Holland
469-473 Biomedical Press
CGA 9795
LYSOSOMAL
HYDROLASES
IN CYSTIC FIBROSIS
LIVERS
JACK A. ALHADEFF Department of Neurosciences, La Jolla, Calif. 92093 (U.S.A.)
(Received
School
of Medicine,
University
of California,
San Diego,
June 7th, 1978)
Summary The specific activity of several lysosomal hydrolases in normal and cystic fibrosis (CF) livers has been investigated. Neuraminidase activity with respect to two natural substrates (fetuin and bovine submaxillary mucin) is normal in CF livers. No significant differences were found between CF and normal livers in 4-methylumbelliferyl-cu-D-mannosidase specific activities determined at three different pH values (4.3, 5.65 and 6.5) corresponding to lysosomal, golgi and cytosolic components of the enzyme, respectively. The specific activities of p-nitrophenyl-fl-D-mannosidase and 4-methylumbelliferyl-P_N-acetylglucosaminidase were also both similar in CF and normal livers.
Introduction Cystic fibrosis (CF) is one of the most common genetic diseases among Caucasian children and manifests itself as a generalized disorder primarily affecting exocrine glands and the pulmonary and gastrointestinal systems [ 1,2]. The fact that CF is transmitted as an autosomal recessive trait [ 31 suggests that the primary biochemical defect involves alteration or lack of a gene product. To date, no one has determined the basic defect in this important disease. Several biochemical studies have been done on lysosomal hydrolases in CF tissues (see rev. ref. 1) but no consistent findings have been found which point to the biochemical defect in this fatal disease. In the present investigation the activities of neuraminidase, fl-D-mannosidase, a-D-mannosidase and fl-N-acetylglucosaminidase in normal and CF livers have been studied. These particular enzymes were chosen for study because of our recent findings of decreased amounts of sialic acid, mannose and iV-acetylglucosamine in the glycoprotein a-L-fucosidase purified from two different CF livers [4]. These altered cY-L-fucosidase carbohydrate compositions could arise from aberrant glycoprotein biosynthesis and/or degradation in cystic fibrosis patients. This study
470
on degradative enzymes is the first report on CF tissues which investigates (1) neuraminidase activity using natural substrates (fetuin and bovine submaxillary mucin), (2) ~-m~nosid~e activity and (3) the activity of the various ar-mannosidases (lysosomal, golgi and cytosolic [ 5,6] ). Previous studies on cu-mannosidase activity in CF tissues [7-91 have not looked at the different forms of this enzyme. Materials and methods General
All procedures were carried out at 0-4°C unless otherwise stated. Protein was determined
