LYSINE-SENSITIVE AND THREONINE-SENSITIVE ASPARTOKINASE ISOENZYMES FROM SPINACH LEAVES SHARE COMMON ANTIGENIC DETERMINANTS

The lysine- and threonine-sensitive isoenzymes of aspartate kinase wer e purified to homogeneity from spinach leaves and polyclonal antibodie s were raised in rabbits. The antibodies were characterized by various immunological tests like Ouchterlonys-double-diffusion, titrations of the inhibition of enzyme activity and ELISA. The antibodies against t he lysine-sensitive isoenzyme could recognise as little as 50 ng of th e pure antigen protein and that against the threonine-sensitive form c ould recognise 200 ng of the protein in the ELISA tests. The immunolog ical tests have also shown that the lysine and threonine sensitive iso enzymes of aspartate kinase share some common antigenic determinants a nd differ in others.