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STABILIZATION OF THE STRUCTURE OF HORSE PLASMA VITAMIN-D BINDING-PROTEIN BY DISULFIDE BONDS

TitleSTABILIZATION OF THE STRUCTURE OF HORSE PLASMA VITAMIN-D BINDING-PROTEIN BY DISULFIDE BONDS
Publication TypeJournal Article
Year of Publication1992
AuthorsRobinson, RC, Burtnick, LD
JournalBiochemistry and Cell Biology-Biochimie Et Biologie Cellulaire
Volume70
Pagination10-15
Date PublishedJan
Type of ArticleArticle
ISBN Number0829-8211
Keywordsactin, circular dichroism, CIRCULAR-DICHROISM, COMPLEX, denaturation, DISULFIDE BONDS, FLUORESCENCE, GC-GLOBULIN, POLYMERIZATION, RAT, SERUM, thermal, TROPOMYOSIN, VITAMIN-D BINDING PROTEIN
Abstract

Vitamin D binding protein (DBP) was isolated from horse plasma in a four-step procedure that involved Affi-Gel Blue affinity chromatography, gel filtration, hydroxylapatite chromatography, and anion exchange high-pressure liquid chromatography. The yield of DBP from 80 mL of plasma was 6-7 mg. Horse plasma DBP closely resembles other plasma DBPs, being a tryptophan-free protein of M(r) 53 000. It is able to bind to and block the polymerization of monomeric actin. The secondary structure of DBP was calculated from circular dichroism measurements to be 39% alpha-helix, 42% beta-sheet, and 19% random coil. Circular dichroism and fluorescence studies revealed that the disulfide bonds of DBP contribute substantial structural stabilization to the molecule with respect to thermal denaturation. The thermal stability of DBP can be used to advantage. Incorporation of a brief treatment at 70-degrees-C into the preparative scheme enables omission of one chromatographic step, without detectable alteration of the purified product.

URL<Go to ISI>://A1992HG74200002