A new variant of glucosephosphate isomerase deficiency (GPI-Utrecht).

A new case of glucosephosphate isomerase deficiency is described in a Dutch family. The activity of the enzyme was decreased to 20-25% of the normal value. Characterization of the defect enzyme showed a pronounced thermolability. Heating of the enzyme at 45 degrees C showed a loss of activity of 90% after one hour. The pH-optimum and the electrophoretic migration were normal. The Km-value for F-6-P, the Ki for the competitive inhibitors 2,3-DPG and 6-PG were in the normal range. The variant described here differs from all known variants. Therefore we propose to give to this new variant the name of GPI-Utrecht.     

Defective erythrocyte pyruvate kinase.

A defective pyruvate kinase (EC 2.7.1.40) is described. The abnormal PK is characterized by a shift in the R in equilibrium T equilibrium to the T-state. The Ko.5 for the substrate phosphoenol pyruvate is about 6 times higher than for the normal enzyme, while the KM value for the positive effector Fru-1, 6-P2 is increased. In agreement with a shift to the T-state is the increased affinity of the abnormal enzyme for the negative effectors ATP and alanine. The results are discussed in relation to other abnormal pyruvate kinases.     

Autonomic nerve calcification and peripheral neuropathy in olivopontocerebellar atrophy

This report concerns an unusual form of olivopontocerebellar atrophy (OPCA) of adult onset, inherited as an autosomal dominant. We examined 5 patients in one generation and performed neuropathological investigations in 3 of these. The clinical and pathological features were different from those of OPCA types I to V. Apart from olivopontocerebellar degeneration, there was dementia in 4, massive atrophy of the spinal cord in 3, and focal degeneration of the optic nerves in at least 1 case. The most remarkable findings were, however, the involvement of the peripheral nervous system and the abundant intrafascicular calcification in sympathetic nerve fibres and in their ganglia.     

Human leucocyte alpha-L-fucosidase.

1. Human alpha-L-fucosidase (EC 3.2.1.51) was studied from leucocytes, urine and serum. 2. The leucocyte and urine enzymes are similar in many properties (KM, pH optimum, electrophoretic pattern, heat stability). 3. The serum alpha-L-fucosidase differs from the leucocyte and 4rine enzyme wit,respect to: electrophoretic pattern, pH optimum and heat stapility. 4. The molecular weight of leucocyte alpha-L-fucosidase was determined to be 80 000 +/- 5000. 5. Cu2+, Hg2+ and PCMB are strong inhibitors of leucocyte alpha-L-fucosidase. This inhibition could be completely reversed by beta-mercaptoethanol, indicating that thiol groups are essential for catalytic activity.     

Characterization of alpha-L-fucosidase from two different families with fucosidosis.

1. Two different families with a different type of fucosidase deficiency are described. 2. In the first family the activity of alpha-L-fucosidase in leucocytes of two patients with fucosidosis type I was about 4 to 8% of the normal value. The activity of alpha-L-fucosidase in the leucocytes of the father and the mother are in the heterozygote range, while a sister of the propositus showed normal values. 3. The activity of alpha-L-fucosidase of the propositus from urine, serum and liver were also severely decreased. The activity of alpha-L-fucosidase in the urine of the parents and the healthy sister of thr propositus were about 5% of the mean normal value. However in the serum these values were above 50%. 4. The KM value for alpha-L-fucosidase from leucocytes of the patient was increased about 10 times and in serum this value was even higher. The KM values from the enzyme of the parents were in the normal range. 5. The abnormal enzyme from the propositus is unique in its thermal behaviour since after heating its activity increased. 6. In the second fanily the activity of alpha-L-fucosidase in the leucocytes of the patient is about 30% of the mean normal value, while the arylsulphatase A activity is also decreased (25% of the mean normal value). 7. The activity of alpha-L-fucosidase from the leucocytes of the father and the healthy brother are about 50% of the mean normal level, while the enzyme of the mother showed a normal activity. 8. The alpha-L-fucosidase activity in the urine and the liver of the propositus is also decreased. The serum enzyme activity however was in the normal range. 9. The KM value of alpha-L-fucosidase and heat stability of the enzyme of the patient were normal. In the leectrophoretic pattern of the whole family one bond was missing.     

Isozyme distribution of hexokinase, phosphofructokinase and pyruvate kinase in lymphocytes from patients with chronic lymphocytic leukemia

The enzyme activities and isozyme distribution of the three glycolytic regulator enzymes hexokinase, phosphofructokinase and pyruvate kinase were studied in lymphocytes of patients with chronic lymphocytic leukemia. Isozyme distribution patterns were determined by kinetic measurements, electrophoresis and immunoprecipitation. The CLL lymphocytes were different from normal non-T lymphocytes with respect to hexokinase residual activity in the presence of glucose-1,6-P2, pyruvate kinase residual activity in the presence of alanine, and phosphofructokinase activity after stimulation by glucose-1,6-P2. No differences could be discerned in enzyme activities between the CLL and the normal T and non-T lymphocytes.