A NOVEL FORM OF PECTINESTERASE IN TOMATO

The pectinesterases in tomato pericarp were fractionated by cation exc hange into four forms (A-D). Form A was the most abundant and C the se cond most abundant. Forms A-C were further purified by gel filtration, and antibodies were raised against A and C. Comparison of the differe nt forms by dot blots and Western blots showed that although all three forms shared common immunological characteristics, there were also di fferences in their behaviour, indicative of structural differences. Fo rm A had an N-terminal sequence identical to that published previously for the major pectinesterase in tomato fruit. In contrast, form C had a completely novel N-terminal sequence. Form A was absent from hypoco tyls and roots. Forms B and C were present in comparable amounts in hy pocotyls, while form C predominated in roots.