Beck, Konrad ![]() |
Abstract
We have analyzed the secondary structure, shape and dimensions of plasma sex steroid-binding protein (SBP) by CD, size-exclusion chromatography and electron microscopy. CD spectra show extrema at 186 nm and 216 nm characteristic for beta-sheet structures. Analysis with different algorithms indicates 15% alpha-helix, 43% beta-sheet and 10-16% beta-turn structures. An irreversible structural change is observed upon heating above 60 degrees C, which correlates with the loss of steroid-binding activity. As the SBP sequence shows similarity with domains of several multidomain proteins, including laminins, we evaluated the structure of domain G of laminin-1. The CD spectrum shows extrema at 200 nm and 216 nm. Deconvolution results in 13% alpha-helix, 32% beta-sheet and 15% beta-turn structures. Steroid-binding assays indicate that laminin and fragments thereof have no activity. Size-exclusion chromatography reveals that SBP has an extended shape and can be modeled as a cylinder with a length and diameter of 23 nm and 3 nm, respectively. This shape and the dimensions are in agreement with the appearance on electron micrographs. We propose a model for the structure of SBP in which two monomers assemble head to head with the steroid-binding site located in the center of the rod-like particle.
Item Type: | Article |
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Date Type: | Publication |
Status: | Published |
Schools: | Dentistry |
Subjects: | Q Science > QD Chemistry |
Uncontrolled Keywords: | plasma sex-steroid-binding protein; sex-hormone-binding globulin; laminin; circular dichroism; hydrodynamics |
Publisher: | Wiley-Blackwell |
ISSN: | 0014-2956 |
Last Modified: | 05 Jan 2024 08:13 |
URI: | https://orca.cardiff.ac.uk/id/eprint/16314 |
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