Partial purification and amino acid sequence analysis of endometriosis protein-II (ENDO-II) reveals homology with tissue inhibitor of metalloproteinases-1 (TIMP-1).
De novo synthesized endometriosis protein-II (ENDO-II; M(r) 28,000 to 32,000; pI 7.0 to 9.0) was partially purified from rat endometriotic tissue culture media using affinity chromatography and two-dimensional SDS-PAGE. The protein was electrophoretically transferred to polyvinyl difluoride membranes which were stained with Coomassie blue R-250. The stained protein corresponding to ENDO-II (M(r) 28,000 to 32,000; pI 7.0 to 9.0) was cut from the membranes for amino acid sequencing. Partial amino acid sequence was determined by automated Edman degradation using a gas phase sequencer and phenylthiohydantoin analyzer. Sequence analysis of ENDO-II yielded 25 residues: C S C A P T H P Q T A F C N S D L V I R K F M G. Comparison to sequence databanks demonstrated significant homology with rat (100%) and human (84%) tissue inhibitor of metalloproteinases-1 (TIMP-1). Western blot analysis using a TIMP-1 antibody confirmed amino acid sequence analysis. In conclusion, ENDO-II shares sequence homology with TIMP-1 and cross-reactivity with TIMP-1 antibody and subsequently identifies production of TIMP-1 by endometriotic tissues. The synthesis and secretion of TIMP-1 by endometriosis may derange the normal proteolytic milieu of the peritoneal cavity and contribute to the etiology and underlying physiological sequelae associated with the disease endometriosis.