THERMAL STABILITY AND CD ANALYSIS OF RAT TYROSINE HYDROXYLASE

摘要: Tyrosine hydroxylase is the rate-limiting enzyme of catecholamine biosynthesis. It a homotetramer made up 56 kDa subunits. We examined thermal stability tyrosine purified from rat pheochromocytoma cell line and investigated relationship between activity stability. Thermal was assessed by incubating at an elevated temperature. Unfolding protein followed measuring loss circular dichroism (CD) 220 nm. The CD biphasic, with half-lives 2 14 min 55 degrees C in 100 mM potassium phosphate, pH 6.0. rate paralleled longer half-life under these conditions. This indicates that structure active site not appreciably change unfolding events corresponding to first phase. Moreover, as spectrum reversible did exhibit well-defined midpoint temperature or Tm. altered several factors influence activity. 6.0 less stable (t1/2 = 6.2 29 min) than 7.2 (a single t1/2 64 min). Phosphorylated had shorter 16 nonphosphorylated 6.0, 50 C, phosphate. Moderate changes phosphate concentration dramatic effects on Decreasing 10 (pH 6.0) increased 23 greater 120 min.(ABSTRACT TRUNCATED AT 250 WORDS)