ISSN:
1573-4919
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Chemistry and Pharmacology
,
Medicine
Notes:
Summary Chloroplasts from spinach can be separated into at least three different populations by countercurrent distribution using polymer two-phase systems. The chloroplast particles of the three populations differ in protein/chlorophyll ratio, ultrastructure and metabolism. One population, peak I, consists of intact chloroplasts surrounded by the chloroplast envelope; the second population, peak II, consists of chloroplasts, which have lost their envelopes and much of their stromal material; the third population, peak III, consists of particles containing intact chloroplasts surrounded by a membrane-bound cytoplasmic layer including mitochondria and peroxisomes. Rapid batch procedures of peak I chloroplasts incorporated14C almost entirely into glycolate and intermediates of the Calvin cycle and starch synthesis. Only small amounts were found in sucrose and amino acids. On the other hand preparations of peak III chloroplasts gave a much broader spectrum of14C-labelled products. Sucrose, malate and some amino acids contained about 40% of the14C incorporated. It is concluded from these experiments that sucrose is formed not within the chloroplast but in the cytoplasm from intermediates exported by the chloroplast. The origin of peak III particles and their use for studying the cooperation between the chloroplast and the surrounding cytoplasm including mitochondria and peroxisomes is discussed.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01744998
Permalink
