![]() ![]() The enzyme ordering can increase metabolic flux by optimizing channeling of pathway intermediates and reducing diffusion distances ( Velot et al., 1997). Metabolons are ordered groups of enzymes within a metabolic pathway that interact to form highly arranged enzyme complexes including sequential ordering of enzymes organized around cytoskeletal elements ( Goetz et al., 1999). The organization of metabolic pathways, such as glycolysis and the tricarboxylic acid cycle, into structurally-coherent units termed metabolons can increase cellular metabolic flux and efficiency ( Robinson et al., 1986 Velot et al., 1997). Those interactions may play specific roles in biochemical adaptation of glycolytic enzymes. Our results support the hypothesis that LDH interacts with glycolytic enzymes in a metabolon structured by cytoskeletal elements that may also include the enzyme for transfer of the adenylate charge in glycolytically produced ATP. Identified proteins included cytoskeletal elements, glycolytic enzymes, a phosphagen kinase, and the respiratory protein hemocyanin. Peptide MS/MS ions were compared to an EST database for Petrolisthes cinctipes to identify proteins. Co-immunoprecipitated proteins were separated using 2D SDS PAGE and analyzed by LC/ESI using peptide MS/MS. Here, we identified proteins that interact with LDH in porcelain crab claw muscle tissue using co-immunoprecipitation, and showed LDH exists in high molecular weight complexes using size exclusion chromatography and Western blot analyses. Interspecific differences in thermal stability of lactate dehydrogenase (LDH) in porcelain crabs (genus Petrolisthes) are related to intrinsic differences among LDH molecules and by interactions with other stabilizing proteins. Enzyme adaptation by alteration of primary structure is well known, but the roles of protein-protein interactions in enzyme adaptation are less well understood. Biochemical adaptation of enzymes involves conservation of activity, stability and affinity across a wide range of intracellular and environmental conditions. ![]()
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