S-tag is a tagged peptide derived from pancreatic ribonuclease A.
S Tag Peptide is a 15 amino acid peptide derived from RNase A.
S Tag is an oligopeptide derived from pancreatic ribonuclease A (RNase A). If RNase A is digested with subtilisin, the monopeptide bond is cleaved to give two weakly bound products, known as ribonuclease S, that remain active, but the two products alone are not enzymatic active. The N-terminus of protoRNase A, also known as S-peptide, consists of 20 amino acids, with only the first 15 amino acids required for RNase activity. These 15 amino acid long peptides are known as S15 or S-tag.
Peptides rich in charged and polar residues have been reported to improve the solubility of the proteins to which they are linked. Moreover, peptides alone cannot be folded into unique structures. At the DNA level, the S-tag can attach to the N-terminus or C-terminus of any protein. Once the gene is expressed, this tagged protein can be detected by commercially available antibodies.