OVINE PLACENTAL LACTOGEN AND OVINE PROLACTIN: PARTIAL PROTEOLYSIS AND CONFORMATIONAL STABILITY

FERNÁNDEZ, M.L; CYMES, G; CURTO, L.; CARLOTA WOLFENSTEIN-TODEL

INTERNATIONAL JOURNAL OF BIOCHEMISTRY AND CELLULAR BIOLOGY

PERGAMON-ELSEVIER SCIENCE LTD

Año: 2000 vol. 32 p. 597 - 608

1357-2725

The high-resolution structure of ovine placental lactogen (oPL) and ovine prolactin (oPRL), not yet established in detail, was probed by limited proteolysis with the Glu-specific protease from Staphylococcus aureus V8. While in hGH (Polverino de Laureto et al., 1995) there were no cleavage sites inside of any of the four  helices, the analysis of the fragments obtained after partial proteolysis of oPL showed a site of cleavage at the putative third helix, suggesting that this helix is partially unwound at this point. The partial proteolysis of the rest of the molecule was compatible with a similar folding pattern for oPL, hGH and pGH, on the basis of the crystal structure of these last hormones. In the case of oPRL, proteolytic cleavage occurred at Glu residues which would be located at the end of the first helix and the beginning of the second in the hGH folding model, suggesting that these helices are shorter in oPRL than in hGH.