Tryptophan synthase in maize ( [formula omitted] L.) : I. [formula omitted] & [formula omitted] demonstration of enzyme activity

Abstract

(3- 14C)-serine was fed through cut ends of 10-day-old shoots of normal (Ganga-2) and opaque (opaque-2) maize ( Zea mays L.) and allowed to be metabolized in light for 24 hours. Subsequent methanolic extraction, radiochromatographic separation and radioautographic analysis showed that 10.4 and 10.3 percent of the absorbed 14C-serine activity was incorporated into L-tryptophan by the shoot tissues of the normal and opaque maize respectively. By coupling extraction of the enzyme with ammonium sulfate precipitation (75% saturation) it was possible to show a serine-dependent indole utilization by the enzyme preparations from coleoptiles (4-day-old), kernels (18 and 28 days after anthesis) and first nodal callus tissues (one-month-old) of the two corn varieties. Furthermore, the indole disappearance from reaction mixture occurred with a concomitant transfer of (3- 14C)-serine appearance into tryptophan.