One Free Sulfhydryl Group of Plasma Fibronectin Becomes Titratable upon Binding of the Protein to Solid Substrates

C. Narasimhan, Ching San Lai, Arthur Haas, James McCarthy

Research output: Contribution to journalArticle

15 Scopus citations

Abstract

The accessibility in human plasma fibronectin of the two free sulfhydryl groups per chain to sulfhydryl reagents 5,5/-dithiobis(2-nitrobenzoic acid) (DTNB) and a maleimide derivative has been examined. For soluble Fibronectin, the free sulfhydryl groups are not accessible to DTNB unless urea or guanidine hydrochloride is added [Smith et al. (1982) J, Biol, Chem. 257, 5831–5838]. Upon binding to polystyrene beads, 0.87 ± 0.05 sulfhydryl group per chain becomes titratable to DTNB. Experiments using fibronectin fragments demonstrate that this newly exposed sulfhydryl group is located in a Type III homologous unit between the DNA-binding and the cell-binding domains. the results suggest that, upon adsorption to solid substrates, plasma fibronectin undergoes a conformational change, thereby exposing one buried sulfhydryl group. These findings have implications regarding the “surface activation” of adhesion activities of fibronectin.

Original languageEnglish (US)
Pages (from-to)4970-4973
Number of pages4
JournalBiochemistry
Volume27
Issue number14
DOIs
StatePublished - Jul 1 1988

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