Comparison of protein patterns among some Salmonella serovars and E. coli by two-dimensional polyacrylamide gel electrophoresis

The study was conducted to compare the protein patterns among some Salmonella serovars and E. coli using Two Dimensional Polyacrylamide Gel Electophoresis. The Two Dimensional Polyacrylamide Gel Electophoresis showed a 37.81 kDa well separated protein spots with all Salmonella serovars at the same time with E. coli a 36.5 kDa protein. However, these protein spots of Two Dimensional Polyacrylamide Gel Electophoresis were further tested with Immunoblotting analysis with specific antiserum against Salmonella typhimurium infected chicks. All selected Salmonella serovars successfully identified a common 37.81 kDa protein whereas E. coli spots identified as 36.5 kDa protein instead of 37.81 kDa. As a further monitoring of these proteins as to check the homogeneity and heterogeneity for N-terminal amino acid sequencing, the specific protein bands from all Salmonella serovars and E. coli were excised, purified and subjected to sequence analysis. The amino acid sequence alignment showed the 37.81 kDa proteins of some Salmonella serovars were identical or homologous among the Salmonella serovars. The N-terminal amino acid alignments of the 37.81 kDa proteins were determined as alanineglutamine- valine-isoleucine-asparagine-threonine-asparagine. On the other hand, the N-terminal amino acid alignment of the 36.5 kDa protein of E . coli ACLD2201 was found to be heterologous as alanine-proline-lysine-aspartic acid-aspararginethreonine- tryptophan. The findings of this study can be concluded that the 37.81 kDa protein of some Salmonella serovars and 36.5 kDa protein of E. coli were completely different though there is some identity of these organisms due to the presence of Enterobacterial common antigen. Key words: Salmonella, 2D-PAGE, amino acid sequence doi: 10.3329/bjvm.v6i2.2324 Bangl. J. Vet. Med. (2008). 6 (2): 127-138