Conformational changes in the progesterone binding globulin-progesterone complex.

S D Stroupe; U Westphal

doi:10.1021/bi00686a002

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Conformational changes in the progesterone binding globulin-progesterone complex.

S D Stroupe·U Westphal

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Abstract

An improved purification procedure for the progesterone-binding globulin (PBG) of the pregnant guinea pig has been developed utilizing sulfopropyl Sephadex, a strong cation exchanger, in the first step. The method exploits the low pI (2.8) and favorable acid stability of the glycoprotein. Subsequent chromatographies on DEAE-cellulose and Sephadex G-200 afford a highly purified PBG that exhibits the previously observed polydispersity (R.M. Burton et al. (1974), Biochemistry 13, 3554-3561). Circular dichroism, optical rotatory dispersion, and difference uv spectra all indicate the purified protein to undergo a conformational transition upon forming a complex with a steroid ligand. The CD and ORD spectra cannot be interpreted in terms of tertiary structure probably due to carbohydrate contributions. However, the difference spectra indicate strong perturbation of both a tryptophan residue and the steroid chromophore in the complex.

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Animals Binding Sites Chromatography, DEAE-Cellulose Chromatography, Gel Chromatography, Ion Exchange Circular Dichroism Electrophoresis, Polyacrylamide Gel Female Guinea Pigs Optical Rotatory Dispersion Pregnancy Progesterone Protein Binding Protein Conformation Receptors, Cell Surface Serum Globulins Spectrophotometry, Ultraviolet Journal Article Research Support, U.S. Gov't, P.H.S.

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S D Stroupe, U Westphal. 1975-07-29. Conformational changes in the progesterone binding globulin-progesterone complex.. https://doi.org/10.1021/bi00686a002

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