SUBUNIT STRUCTURE OF HALOPHILIC MALATE-DEHYDROGENASE FROM HALOARCULA-MARISMORTUI

1. The subunit structure of halophilic malate dehydrogenase from Haloa rcula marismortui was studied by the method of crosslinking with bifun ctional reagent.2. Exposure of the enzyme to glutardialdehyde followed by sodium dodecyl sulphate gel electrophoresis resulted in the appear ance of four bands with mobilities corresponding to monomeric polypept ide chains and crosslinked polypeptide chain dimers, trimers and tetra mers. 3. Our findings are not consistent with the currently accepted d imeric structure of the enzyme. They provide a strong indication that halophilic malate dehydrogenase is composed of four identical subunits .