Prediction of secondary structure of the tag by indicates that the sequence forms two helixes which give stability and coiled structures between these two helices. The coiled structrure may adoptthe protein to bind a receptor without altering xylase conforma-tion or stability. Further, the coiled structure provides flexibilityand facilitates binding. Proline structure restricts most of the conformational changes but proline rich amino acid site has smooth hydrophobic surface with charged amino acids at the perifery. This provides selectivity resulting from the periferic amino acids.