journal of kerbala university

Helicobacter pylori have many virulence factors among them CagA and VacA toxins. Protein sequences of these toxins isolated form Iraqi patients were studied using different software. Results showed that amino acids composition is clearly differ from strains of other countries like China and Japan. Amino acids sequences had some conservation compared to VacA sequence(s). Hydrophobicity was the major character of the sequences. Amino acids segregated on different secondary structures : β sheets , α helixes and coils with non-homogenous patterns , some got all the structures , VacA (m and I regions ) devoted of α helixes , s1 has α helixes and β sheets , while s2 has only α helixes . Activity studies of CagA which depends on its tyrosine phsphorylation at EPIYA motif revealed that such sequence provide the environment for phosphorylation, since the insertion of tyrosine outside the motif showed no phosphorylation. The study indicates that all sequences are antigenic and most of them are virulent. Their interactions with other cell components using STRING database explain that the interaction is very complicated and depends on sequence.