Identification of a novel gene encoding lactate dehydrogenase from Spirometra erinaceieuropaei and prediction for its structure and function

To identify the full length cDNA sequence encoding lactate dehydrogenase(LDH)from adult Spirometra erinaceieuropaei(S.e.)and to predict the structure and function of the protein. Methods Some online websites such as NCBI,EMBI,Expasy and a softw are packages Vector NTI were exploited to analyze the sequence bioinformatics, including the open reading frame(ORF),conserved structure and functional domain,multi-sequence homological alignment, phylogenetic analysis,topological prediction,homology modeling of tertiary structure,and antigenic epitope analysis. Results The target sequence had a full ORF,typical L-LDH structure domain,full conserved domain and polyA.It was confirmed as a full length cDNA encoding LDH of S.e.and then named as SeLDH(GU121968).The sequence encodes a protein of 338 amino acids with the predicted molecular weight of 36 028.6Da and isoelectric point of 6.38.Compared with the LDHs of Clonorchis sinensis,Schistosoma japonicum and human,the similarity of SeLDH is 60%,59%,and 55%,respectively.In the protein,5 transmembrane regions were found and 185-191aa,223-235aa,328-338aa of the 5 major epitopes were presented with significant difference compared to the same region of human LDH.There is only 1aa difference between epitope 104-111aa of SeLDH and that of human,which is an important function region containing 2 NAD binding sites and 1 substrate binding site and the key catalytic residue 112R is close to the region.Tertiary structure demonstrates that 104-111aa is on the surface of the protein and forms a substrate binding loop,three key catalytic sites and NAD,pyruvate binding sites formed a catalytic center near the loop. Conclusion The full length cDNA sequence of a novel gene SeLDH was obtained.The bioinformatics implies that SeLDH might be a transmembrane protein and an ideal molecule for immunodiagnosis,vaccine and drug reaction.