Soluble starch synthases and starch branching enzymes from developing seed of teosinte

Previously three fractions of soluble starch branching enzyme and two fractions of soluble starch synthase were found in developing maize kernels using DEAE-cellulose chromatography (Boyer and Preiss, Carbohydr. Res. 61:321, 1978). The enzymes from two teosintes have now been examined. Seed from self-pollinated Galinat's northern teosinte (annual) and Zea diploperennis (perennial) were collected at 20 days after pollination, quick-frozen and stored at -80 C until used. Soluble starch synthases and branching enzymes were purified as described in detail elsewhere (Boyer and Preiss, Plant Physiol. 67:1141, 1981).

DEAE cellulose chromatography of extracts from both teosintes separated the starch synthases into two fractions and the branching enzymes into three fractions. A typical DEAE-cellulose profile is presented in Figure 1. DEAE-cellulose fraction I (column fractions 4-13) contained branching enzyme I. DEAE-cellulose fraction II (column fractions 36-64) contained branching enzyme IIb and citrate-stimulated starch synthase activities. DEAE-cellulose fraction III (column fractions 65-88) contained branching enzyme IIb and primer-requiring starch synthase activities. Characterization of concentrated DEAE-cellulose fractions revealed no differences between the teosinte enzymes and the maize enzymes previously reported. The teosinte branching enzymes are similar to maize branching enzymes in respect to chromatographic properties and relative activities in two different assay procedures. The teosinte starch synthases are similar to the maize enzymes in regard to chromatographic properties, activity in the presence of citrate (no primer) and relative reaction rates in reaction mixtures containing different glucan primers. Although electrophoretic variation was not ruled out, these studies suggest that the catalytic properties of soluble starch synthases and branching enzymes are conserved in Zea. Additional races of teosinte will be examined in the future to explore this hypothesis.

Figure 1.

Charles D. Boyer

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