Enzymatic and Metabolic Studies of Homocystinuria: Effects of Pyridoxine

Gerald E. Gaull; David K. Rassin; John A. Sturman

doi:10.1055/s-0028-1091874

Neuropädiatrie, Table of Contents

Neuropediatrics 1969; 1(2): 199-226
DOI: 10.1055/s-0028-1091874

Original article

Enzymatic and Metabolic Studies of Homocystinuria: Effects of Pyridoxine[*]

Gerald E. Gaull, David K. Rassin, John A. Sturman

Department of Pediatric Research, New York State Institute for Basic Research in Mental Retardation, Staten Island, New York, the Department of Pediatrics and Clinical Research Center, Mt. Sinai Hospital School of Medicine, and the Departments of Pediatrics and Neurology, Columbia-Presbyterian Medical Center, New York

Abstract

There is a wide spectrum of biochemical response to massive doses of pyridoxine in patients with homocystinuria. Metabolic and enzymatic studies in these patients, before and after such treatment, establish that the effect of pyridoxine, in the patient who responds, is not on cystathionine synthase of liver. In patients with homocystinuria treated with methionine-restricted diet, supplemented with cysteine, there is a striking reduction in activity of methionine-activating enzyme, as well as an absence of activity of cystathionine synthase. In patients with homocystinuria treated with pyridoxine over a long period of time, there is a dramatic increase in activity of cystathionase of liver. The formation of chemical artifacts in crude enzymatic extracts to which large amounts of pyridoxal phosphate are added, render interpretation of changes in activity of the affected enzyme in “pyridoxine-dependency” states equivocal, unless the product of the reaction is rigorously identified.

Homocystinuria - Cystathionine Synthase - Methionine-activating Enzyme - Cystathionase Pyridoxine-dependency - Pyridoxal Phosphate

Full Text

References

1 Presented in part at the European Club for Pediatric Reserach, Vienna, August, 1968 and abstracted in Pediat.