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Comparison of the D-lactate stereospecif ... ons of L-lactate dehydrogenases
Comparison of the D-lactate stereospecific dehydrogenase of Limulus polyphemus with active-site regions of L-lactate dehydrogenases.
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Lactate dehydrogenase (D-lactate:NAD+ oxidoreductase, EC 1.1.1.28) from the horseshoe crab, Limulus polyphemus, a dimeric enzyme stereospecific for D-lactate, has been purified by affinity chromatography. Maleyl tryptic peptides containing arginine residues isolated from the Limulus enzyme have been characterized and sequenced. The small peptides obtained from similarly treated L-lactate-specific enzyme homologs define major portions of the substrate and coenzyme binding regions and are virtually identical among L-lactate-specific enzymes. Although the six small peptides and free arginine isolated from the Limulus enzyme indicate that the small number of arginine tryptic peptides are located in a few discrete consecutive clusters similarly to the L-lactate dehydrogenases, the peptides nevertheless show no obvious sequence homology to the corresponding peptides from L-lactate dehydrogenases. These results indicate that this lactate dehydrogenase of altered substrate specificity either evolved with major rearrangements of the active site if it evolved from an L-lactate dehydrogenase, or that D-lactate dehydrogenases have evolved from a different protein. The results contradict proposed models which suggest that minor changes in the spatial orientation of pyruvate resulting from minimal rearrangement of the active site could accommodate the change in substrate specificity.
Siebenaller JF, Orr TL, Olwin BB, Taylor SS
Biochimica et biophysica acta
1983-12-12 00:00
749
2
153-62
Amino Acid Sequence,Animals,Binding Sites,Evolution,Horseshoe Crabs,L-Lactate Dehydrogenase,Peptide Fragments,Stereoisomerism,Structure-Activity Relationship,Substrate Specificity,Peptide Fragments,L-Lactate Dehydrogenase
Biochim. Biophys. Acta
NIGMS GM 06728, NIGMS GM 22452
0006-3002
857
True
6652095
