Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:1.9.3.1 (cytochrome oxidase)
 8,822 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A proton-pumping heme aa3-type cytochrome oxidase purified from the thermophilic bacterium PS3 was treated with trypsin, thermolysin, chymotrypsin, subtilisin, or pronase. The cleavage of the oxidase subunits and the effects of their cleavage on the oxidase activity and proton-pumping in reconstituted vesicles were studied. Trypsin and thermolysin cleaved some of the oxidase subunits without affecting the proton-pumping, but subtilisin and pronase cleaved all the subunits resulting in partial decrease in both activities. Chymotrypsin had an intermediate effect. Subunit II of this enzyme contains heme c which is also cleaved by proteases.
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PMID:Proton pumping and oxidase activity of thermophilic cytochrome oxidase remain after its extensive proteolysis. 630 93

Phosphoenolpyruvate carboxylase (PEPC) from developing castor oil seeds (COS) exists as two distinct oligomeric isoforms. The typical class-1 PEPC homotetramer consists of 107-kDa plant-type PEPC (PTPC) subunits, whereas the allosterically desensitized 910-kDa class-2 PEPC hetero-octamer arises from the association of class-1 PEPC with 118-kDa bacterial-type PEPC (BTPC) subunits. The in vivo interaction and subcellular location of COS BTPC and PTPC were assessed by imaging fluorescent protein (FP)-tagged PEPCs in tobacco suspension-cultured cells. The BTPC-FP mainly localized to cytoplasmic punctate/globular structures, identified as mitochondria by co-immunostaining of endogenous cytochrome oxidase. Inhibition of respiration with KCN resulted in proportional decreases and increases in mitochondrial versus cytosolic BTPC-FP, respectively. The FP-PTPC and NLS-FP-PTPC (containing an appended nuclear localization signal, NLS) localized to the cytosol and nucleus, respectively, but both co-localized with mitochondrial-associated BTPC when co-expressed with BTPC-FP. Transmission electron microscopy of immunogold-labeled developing COS revealed that BTPC and PTPC are localized at the mitochondrial (outer) envelope, as well as the cytosol. Moreover, thermolysin-sensitive BTPC and PTPC polypeptides were detected on immunoblots of purified COS mitochondria. Overall, our results demonstrate that: (i) COS BTPC and PTPC interact in vivo as a class-2 PEPC complex that associates with the surface of mitochondria, (ii) BTPC's unique and divergent intrinsically disordered region mediates its interaction with PTPC, whereas (iii) the PTPC-containing class-1 PEPC is entirely cytosolic. We hypothesize that mitochondrial-associated class-2 PEPC facilitates rapid refixation of respiratory CO(2) while sustaining a large anaplerotic flux to replenish tricarboxylic acid cycle C-skeletons withdrawn for biosynthesis.
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PMID:Bacterial- and plant-type phosphoenolpyruvate carboxylase isozymes from developing castor oil seeds interact in vivo and associate with the surface of mitochondria. 2240 38