title: Purification, properties and immunological relationship of L (+)-lactate dehydrogenase from Lactobacillus casei.
abstract: The fructose-1,6-bisphosphate-activated L-lactate dehydrogenase (EC 1.1.1.27) from Lactobacillus casei ATCC 393 has been purified to homogenity by including affinity chromatography (cibacronblue-Sephadex-G-200) and preparative polyacrylamide gel electrophoresis into the purification procedures. The enzyme has an Mr of 132000-135000 with a subunit Mr of 34000. The pH optimum was found to be 5.4 insodium acetate buffer. Tris/maleate and citrate/phosphate buffers inhibited enzyme activity at this pH. The enzyme was completely inactivated by a temperature increase from 60 degrees C to 70 degrees C. Pyruvate saturation curves were sigmoidal in the absence of fructose 1,6-bisphosphate. In the presence of 20 muM fructose 1,6-bisphosphate a Km of 1.0 mM for pyruvate was obtained, whereas fructose 1,6-bisphosphate had no effect on the Km of 0.01 mM for NADH. The use of pyruvate analogues revealed two types of pyruvate binding sites, a catalytic and an effector site. The enzyme from L. casei appears to be subject to strict metabolic control, since ADP, ATP, dihydroxyacetone phosphate and 6-phosphogluconate are strong inhibitors. Immunodiffusion experiments with a rabbit antiserum to L. casei lactate dehydrogenase revealed that L. casei ATCC 393 L (+)-lactate dehydrogenase is probably not immunologically related to group D and group N streptococci. Of 24 lactic acid bacterial strains tested only 5 strains did cross-react: L. casei ATCC 393 = L. casei var. rhamnosus ATCC 7469 - L. casei var. alactosus NCDO 680 greater than L. casei UQM 95 greater than L. plantarum ATCC 14917.
mesh_terms: D002413:Cations, Divalent; D005779:Immunodiffusion; D007122:Immunoelectrophoresis; D007700:Kinetics; D007770:L-Lactate Dehydrogenase / Q000032:analysis / Q000302:isolation & purification / Q000378:metabolism*; D007780:Lacticaseibacillus casei / Q000201:enzymology*; D046911:Macromolecular Substances; D008970:Molecular Weight; D011773:Pyruvates / Q000494:pharmacology; D013045:Species Specificity; D013329:Structure-Activity Relationship; D013439:Sulfhydryl Reagents / Q000494:pharmacology
chemical_list: D002413:Cations, Divalent; D046911:Macromolecular Substances; D011773:Pyruvates; D013439:Sulfhydryl Reagents; D007770:L-Lactate Dehydrogenase