title: Chloroplast grana membrane carboxyl groups: their involvement in membrane association.
abstract: 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.
authors: Departments of Biochemistry and Biological Sciences, Purdue University, West Lafayette, Indiana, 47905.
authors: S
authors: S
authors: Berg
authors: S
authors: S
authors: Dodge
authors: D W
authors: DW
authors: Krogmann
authors: R A
authors: RA
authors: Dilley