Determination of Some Molecular Parameters of Tyrosine Hydroxylase From Rat Adrenal, Rat Striatum, and Human Pheochromocytoma

Abstract

The molecular parameters of tyrosine hydroxylase from rat adrenal, rat striatum, and human pheochromocytoma were determined by combined gel filtration and sucrose gradient ultracentrifugation. The enzyme from rat adrenal has a calculated MW of 228,000, a Stokes radius of 60.9 .ANG., a sedimentation coefficient of 9.10S, and a frictional ratio of 1.39. The enzyme from rat striatum has a calculated MW of 210,000, a Stokes radius of 54.3 .ANG., a sedimentation coefficient of 9.38S, and a frictional ratio of 1.28. Tyrosine hydroxylase from human pheochromocytoma tissue has a calculated MW of 255,000, a Stokes radius of 68.2 .ANG., a sedimentation coefficient of 9.08S, and a frictional ratio of 1.50. The tyrosine hydroxylases from central and peripheral tissue in the rat are quite similar although the human enzyme appears to be significantly larger.