Beschreibung:
<jats:p>Several enzymes of non–photosynthetic sugar phosphate and starch metabolism were measured in gradient–purified chloroplasts from normal rye leaves (<jats:italic>Secale cereale</jats:italic> L. cv. Halo) grown at 22°C and in the non‐photosynthetic plastids isolated from 70S ribosome‐deficient rye leaves grown at a non–permissive elevated temperature of 32°C. Activities of the enzymes phosphoglycerate kinase (EC 2.7.2.3), hexokinase (EC 2.7.1.1), phosphoglucose isomerase (EC 5.3.1.9), phosphoglucomutase (EC 2.7.5.1), glucose‐6‐phosphate dehydrogenase (EC 1.1.1.49), 6‐phosphogluconate de‐hydrogenase (EC 1.1.1.46), ADPglucose pyrophosphorylase (EC 2.7.7.27), starch synthase (EC 2.4.1.21), and phosphorylase (EC 2.4.1.1) were present in ribosome‐deficient plastids from 32°C‐grown leaves indicating a cytoplasmic origin of the plastid‐specific forms of these enzymes. While the photosynthetic marker enzyme NADP<jats:sup>+</jats:sup>‐dependent glyceraldehyde‐3‐phosphate dehydrogenase (EC 1.2.1.13) was considerably diminished, both the specific activities and the total activities per leaf of the plastid‐specific forms of hexokinase, phosphoglucose isomerase and phosphoglucomutase were markedly increased in the ribosome–deficient plastids, relative to normal chloroplasts. The results demonstrate that after elimination of functional protein synthesis in the chloroplasts the supply of chloroplast–specific enzymes by the cytoplasm is not generally suppressed as observed for many enzymes and proteins involved in photosynthesis, but may even be increased in accord with changed metabolic demands.</jats:p>