Open AccessChloroplast Grana Membrane Carboxyl Groups
Author(s) -
Steven P. Berg,
Stephen Dodge,
David W. Krogmann,
Richard A. Dilley
Publication year - 1974
Publication title -
plant physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.554
H-Index - 312
eISSN - 1532-2548
pISSN - 0032-0889
DOI - 10.1104/pp.53.4.619
Subject(s) - membrane , chloroplast , chemistry , carbodiimide , stacking , thylakoid , chloroplast membrane , glycine , salt (chemistry) , biophysics , cationic polymerization , crystallography , amino acid , biochemistry , biology , organic chemistry , gene
Chloroplast membrane carboxyl groups were modified by carbodiimide activation followed by glycine methyl ester substitution, leaving the derivatized group uncharged. This charge alteration induced a number of effects similar to addition of salts to control chloroplasts suspended in a low salt medium. These include: (a) restacking or multiple membrane association in low salt-treated chloroplasts that lack grana stacks, (b) protection against polycation inhibition of photosystem I electron transfer, (c) reduction of the amount of polycations bound to the membranes, and (d) increased 90 degrees light scattering due to membrane conformational changes. Carboxyl modification also altered acid-induced conformational changes.These effects are interpretated as the results of the reduction in the surface negative charge contributed by carboxyl groups. Membrane structure at both a local, polyelectrolyte level and at the level of membrane-membrane interaction (stacking) is controlled in part by these negative, charged groups.