Immunoaffinity purification and characterization of a human liver-specific antigen.

We have purified a liver-specific antigen (LSA) from human liver by using immunoaffinity chromatography followed by other procedures and examined its biochemical properties. Amino acid analysis of the purified LSA revealed that the sum of acidic amino acids was probably higher than that of basic amino acids; this agrees with its pI of 5.8-5.9. The protein had also relatively large amount of Pro and the NH2-terminal amino acid sequence from 2nd to 8th residues was determined to be Pro-Pro-Ser-Pro-Pro-Val-Val. A computer search showed that the human LSA has no significant homology to any other proteins available from sequence databases. These findings, together with those reported previously, suggest that the human LSA will be useful as a powerful marker for detecting liver injury.