TY - JOUR
T1 - Differential inhibition of Pi-ATP exchange in relation to ATP synthesis and hydrolysis by modification of chloroplast thylakoid membranes with glutaraldehyde
AU - Bar-Zvi, Dudy
AU - Shavit, Noun
N1 - Funding Information:
We wish to thank Mrs. Z. Conrad for excellent technical assistance, and Dr. M.A. Tiefert for help in the preparation of this manuscript. This work was supported in part by a grant from the Deutsche Forschungsgemeinschaft.
Copyright:
Copyright 2014 Elsevier B.V., All rights reserved.
PY - 1983/9/30
Y1 - 1983/9/30
N2 - Limited modification of thylakoid membranes with glutaraldehyde inhibits the Pi-ATP exchange reaction much more than ATP synthesis or hydrolysis. More extensive modification of the membranes results in the inhibition of all activities of the ATP synthetase, but does not affect electron transport. Limited modification also does not have much effect on the tight binding of [3H]ADP or the ΔpH supported by ATP hydrolysis. The modification affects the catalytic process itself and not the activation of the latent enzyme. Cross-linking between thylakoid polypeptides is observed only after extensive treatment with glutaraldehyde, while limited modification does not result in cross-linking between polypeptides. The differential inhibition of the Pi-ATP exchange relative to ATP hydrolysis can be explained by the decrease in only one of the kinetic rate constants involved in these reactions. However, the relative insensitivity of photophosphorylation to the modification suggests that different enzyme conformations may participate in phosphorylation (light) and ATP hydrolysis or Pi-ATP exchange (dark).
AB - Limited modification of thylakoid membranes with glutaraldehyde inhibits the Pi-ATP exchange reaction much more than ATP synthesis or hydrolysis. More extensive modification of the membranes results in the inhibition of all activities of the ATP synthetase, but does not affect electron transport. Limited modification also does not have much effect on the tight binding of [3H]ADP or the ΔpH supported by ATP hydrolysis. The modification affects the catalytic process itself and not the activation of the latent enzyme. Cross-linking between thylakoid polypeptides is observed only after extensive treatment with glutaraldehyde, while limited modification does not result in cross-linking between polypeptides. The differential inhibition of the Pi-ATP exchange relative to ATP hydrolysis can be explained by the decrease in only one of the kinetic rate constants involved in these reactions. However, the relative insensitivity of photophosphorylation to the modification suggests that different enzyme conformations may participate in phosphorylation (light) and ATP hydrolysis or Pi-ATP exchange (dark).
KW - ATPase
KW - Chemical modification
KW - Glutaraldehyde
KW - P-ATP exchange
KW - Photophosphorylation
KW - Thylakoid modification
UR - http://www.scopus.com/inward/record.url?scp=48749144598&partnerID=8YFLogxK
U2 - 10.1016/0005-2728(83)90088-9
DO - 10.1016/0005-2728(83)90088-9
M3 - Article
AN - SCOPUS:48749144598
SN - 0005-2728
VL - 724
SP - 299
EP - 308
JO - Biochimica et Biophysica Acta - Bioenergetics
JF - Biochimica et Biophysica Acta - Bioenergetics
IS - 3
ER -