Relaxin from an oviparous species, the skate (Raja erinacea)

An acid-acetone extract prepared from ovaries of the skate, Raja erinacea, contained a weakly crossreacting molecule when tested in a pig relaxin radioimmunoassay. The material was isolated and purified to homogeneity by ion exchange chromatography, molecular exclusion chromatography, and HPLC. Analytical tests proved the molecule to consist of two chains and to have a molecular weight of 7,500. Sequence analyses of the A and B chains yielded the following sequence: Glu-Glu-Lys-Met-Gly-Phe-Ala-Lys-Lys-Cys-Cys-Ala-Ile-Gly-Cys-Ser-Thr-Glu- Asp-Phe-Arg-Met-Val-Cys and Arg-Pro-Asn-Trp-Glu-Glu-Arg-Ser-Arg-Leu-Cys-Gly-Arg-Asp-Leu-Ile-Arg-Ala- Phe- Ile-Tyr-Leu-Cys-Gly-Gly-Thr-Arg-Trp-Thr-Arg-Leu-Pro-Asn-Phe-Gly-Asn-Tyr- Pro-Ile-Met respectively. Skate relaxin has 0.2% of the activity of B29 pig relaxin in the symphysis pubis assay and 0.5% in the mouse uterine muscle strip contraction inhibition assay.