TY - JOUR
T1 - Two monoclonal antibody lines directed against Subunit IV of cytochrome oxidase
T2 - A study of opposite effects
AU - Gai, Wen Zhi
AU - Sun, Shu Man
AU - Ding, You Zhan
AU - Freedman, Jo A.
AU - Chan, Samuel H.P.
N1 - Funding Information:
1 Supported by National GM 32246. *To whom correspondence
PY - 1988/11/1
Y1 - 1988/11/1
N2 - Two monoclonal lines of antibodies were isolated with specificities against the amino half of Subunit IV of beef heart cytochrome oxidase. The lines had nonoverlapping epitopes. Both bound to the matrix face of membranous oxidase, neither bound to the cytoplasmic face. One line ( QA4 C4) stimulated electron transfer in soluble or membranous oxidase, while the other (QA4) inhibited that activity by both oxidase preparations. These effects on electron transfer activity were not altered by the inclusion or omission of detergent. ATP depressed the binding of either antibody to either soluble or membranous oxidase. In the absence of ATP, QA4 C4 stimulated electron transfer only in the high affinity phase of cytochrome c oxidation (with decreased KM and increased Vmax), causing slight inhibition in the low affinity phase (with decreased KM). In the presence of ATP, QA4 C4 abolished the high affinity phase, but did not alter the ATP influence on the low affinity phase. In the absence of ATP, antibodies of line QA4 abolished the low affinity phase, leaving a high affinity phase similar to that induced by ATP. In the presence of ATP, QA4 abolished the high affinity phase, leaving a low affinity phase similar to that seen with ATP alone. This behavior is consistent with the dissection of two catalytic sites for cytochrome c and more than one ATP affector site.
AB - Two monoclonal lines of antibodies were isolated with specificities against the amino half of Subunit IV of beef heart cytochrome oxidase. The lines had nonoverlapping epitopes. Both bound to the matrix face of membranous oxidase, neither bound to the cytoplasmic face. One line ( QA4 C4) stimulated electron transfer in soluble or membranous oxidase, while the other (QA4) inhibited that activity by both oxidase preparations. These effects on electron transfer activity were not altered by the inclusion or omission of detergent. ATP depressed the binding of either antibody to either soluble or membranous oxidase. In the absence of ATP, QA4 C4 stimulated electron transfer only in the high affinity phase of cytochrome c oxidation (with decreased KM and increased Vmax), causing slight inhibition in the low affinity phase (with decreased KM). In the presence of ATP, QA4 C4 abolished the high affinity phase, but did not alter the ATP influence on the low affinity phase. In the absence of ATP, antibodies of line QA4 abolished the low affinity phase, leaving a high affinity phase similar to that induced by ATP. In the presence of ATP, QA4 abolished the high affinity phase, leaving a low affinity phase similar to that seen with ATP alone. This behavior is consistent with the dissection of two catalytic sites for cytochrome c and more than one ATP affector site.
UR - http://www.scopus.com/inward/record.url?scp=0023733241&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0023733241&partnerID=8YFLogxK
U2 - 10.1016/0003-9861(88)90296-2
DO - 10.1016/0003-9861(88)90296-2
M3 - Article
C2 - 2461167
AN - SCOPUS:0023733241
SN - 0003-9861
VL - 266
SP - 628
EP - 638
JO - Archives of Biochemistry and Biophysics
JF - Archives of Biochemistry and Biophysics
IS - 2
ER -