TY - JOUR
T1 - Modification of histidine at the active site of spinach ribulose bisphosphate carboxylase
AU - Saluja, Ashok K.
AU - McFadden, Bruce A.
PY - 1980/6/30
Y1 - 1980/6/30
N2 - Ribulose 1,5-bisphosphate carboxylase from spinach was rapidly inactivated by diethylpyrocarbonate (DEP) at pH 7.0 and 30°C. The inactivation showed saturation kinetics with a half-inactivation time at saturating DEP equal to 0.1 minutes and KDEP = 7.4 mM. One substrate, ribulose bisphosphate, the product 3-phosphoglycerate and two competitive inhibitors protected against inactivation, thereby indicating that DEP modifies the active site. DEP-modified enzyme showed an increased absorption at 240 nm which was lost upon treatment with 0.4 M hydroxylamine. Most of the activity lost by DEP modification could be restored after treatment with 0.4 M hydroxylamine at 4°C. The results suggest that DEP modified 2 to 3 histidine residues per 70,000-dalton combination of large and small subunits. These residues are essential to catalysis by the carboxylase activity of ribulose bisphosphate carboxylase/oxygenase.
AB - Ribulose 1,5-bisphosphate carboxylase from spinach was rapidly inactivated by diethylpyrocarbonate (DEP) at pH 7.0 and 30°C. The inactivation showed saturation kinetics with a half-inactivation time at saturating DEP equal to 0.1 minutes and KDEP = 7.4 mM. One substrate, ribulose bisphosphate, the product 3-phosphoglycerate and two competitive inhibitors protected against inactivation, thereby indicating that DEP modifies the active site. DEP-modified enzyme showed an increased absorption at 240 nm which was lost upon treatment with 0.4 M hydroxylamine. Most of the activity lost by DEP modification could be restored after treatment with 0.4 M hydroxylamine at 4°C. The results suggest that DEP modified 2 to 3 histidine residues per 70,000-dalton combination of large and small subunits. These residues are essential to catalysis by the carboxylase activity of ribulose bisphosphate carboxylase/oxygenase.
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U2 - 10.1016/0006-291X(80)90531-8
DO - 10.1016/0006-291X(80)90531-8
M3 - Article
C2 - 7396952
AN - SCOPUS:0019335876
VL - 94
SP - 1091
EP - 1097
JO - Biochemical and Biophysical Research Communications
JF - Biochemical and Biophysical Research Communications
SN - 0006-291X
IS - 4
ER -