Maralihalli, GBhagwat, A S2001-12-072009-05-272001-12-072009-05-272001-12-07Maralihalli G, Bhagwat AS. Limited proteolysis by trypsin influences activity of maize phosphoenolpyruvate carboxylase. Indian Journal of Biochemistry & Biophysics. 2001 Dec; 38(6): 361-7http://imsear.searo.who.int/handle/123456789/27937Maize phosphoenolpyruvate carboxylase (PEPC) was rapidly and completely inactivated by very low concentrations of trypsin at 37 degrees C. PEP+Mg2+ and several other effectors of PEP carboxylase offered substantial protection against trypsin inactivation. Inactivation resulted from a fairly specific cleavage of 20 kDa peptide from the enzyme subunit. Limited proteolysis under catalytic condition (in presence of PEP, Mg2+ and HCO3) although yielded a truncated subunit of 90 kDa, did not affect the catalytic function appreciably but desensitized the enzyme to the effectors like glucose-6-phosphate glycine and malate. However, under non-catalytic condition, only malate sensitivity was appreciably affected. Significant protection of the enzyme activity against trypsin during catalytic phase could be either due to a conformational change induced on substrate binding. Several lines of evidence indicate that the inactivation caused by a cleavage at a highly conserved C-terminal end of the subunit.engBicarbonates --pharmacologyFluorescenceGlucose-6-Phosphate --pharmacologyGlycine --pharmacologyKineticsMagnesium --pharmacologyMalates --pharmacologyPhosphoenolpyruvate Carboxylase --antagonists & inhibitorsPhosphorylationProtein ConformationSulfhydryl Compounds --chemistryTrypsin --pharmacologyZea mays --enzymologyJournal Article