The accessible cysteine residue of human transcortin

Gaillard, F; Dautrevaux, M

doi:10.1016/0014-5793(78)80907-7

Cited by 14 publications

(6 citation statements)

References 21 publications

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“…Two sulfhydryl groups, however, were detected in reduced, denatured CBG (Table III). These data confirm the results previously reported by Le Gaillard & Dautrevaux (1978), who assume the presence of one sulfenic acid group which is reducible by mild reductants. The data support the conclusion that CBG contains one sterically hindered cysteine that is exposed only after denaturation and one cysteine that is titratable only after reduction.…”

Section: Resultssupporting

confidence: 93%

“…Removal of the reducing agent by dialysis reversed the effect. The number of binding sites was not altered in the presence of reducing agent in agreement with published results (Le Gaillard & Dautrevaux, 1978). A possible explanation of these findings is that a cysteine residue(s) becomes oxidized during the isolation of CBG, which results in a conformation capable of binding steroids more avidly.…”

Section: Discussionsupporting

confidence: 91%

“…One thiol group was titratable with DTNB after denaturation with NaDodS04 and a second one in the presence of reducing agents, in agreement with published results (Le Gaillard & Dautrevaux, 1978;Defaye et al, 1980). The The involvemen) of a cysteinyl residue in the steroid binding process of human CBG is not clear.…”

Section: Discussionsupporting

confidence: 85%

“…of a disulfide bond as proposed bySeal & Doe (1966) appears unlikely; denaturation of CBG by NaDodS04 or exposure to ascorbate or arsenite resulted in the appearance of one titratable sulfhydryl group which could not result if a disulfide bond existed. It appears that CBG when isolated contains two distinguishable "cysteine" residues, one oxidized and one exposed only by denaturation (LeGaillard & Dautrevaux, 1978).…”

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confidence: 99%

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Steroid-protein interactions. Human corticosteroid binding globulin: some physicochemical properties and binding specificity

Mickelson¹,

Forsthoefel²,

Westphal³

1981

Biochemistry

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Reducing agents (dithiothreitol and beta-mercaptoethanol) significantly decrease the affinity constants of the human corticosteroid-binding globulin (CBG)-cortisol complex in proportion to their concentration; the resulting Ka values are more consistent than those obtained in the absence of the reductants. The effect is reversible. The equilibrium association constants of the CBG complexes with cortisol and progesterone show a relatively broad pH maximum between pH 8 and 11. In this pH range, cortisol was found to be bound more strongly than progesterone; this relationship is reversed around pH 6. The van't Hoff plot of the temperature effect on Ka of the CBG-cortisol complex (4-41 degrees C) exhibits a nonlinear, possibly biphasic temperature dependency. The shape of the van't Hoff plot was similar in the presence of mercaptoethanol. The association of cortisol and progesterone to human CBG at 4 and 37 degrees C is enthalpy driven, compensating for the unfavorable change in entropy. Studies with 47 steroids served to elucidate the influence on binding affinity of polar and nonpolar groups and other structural alterations. The contribution of specific structural changes in the steroid molecule to the free energy of binding can be calculated from the results. Important structures for optimal binding are the 20-oxo group, a 10 beta-methyl group, and a double bond at the 4 position. A complementary image of the binding site with respect to the nature of binding at various locations is proposed.

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Section: Resultssupporting

confidence: 93%

Section: Discussionsupporting

confidence: 91%

Section: Discussionsupporting

confidence: 85%

mentioning

confidence: 99%

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Steroid-protein interactions. Human corticosteroid binding globulin: some physicochemical properties and binding specificity

Mickelson¹,

Forsthoefel²,

Westphal³

1981

Biochemistry

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“…Moreover, a mild reduction of the proteins with sodium arsenite was performed. In the case of SH groups having been partially oxidized into sulfenic or sulfinic radicals, this treatment would have reconverted them into their primitive forms [11]. No SH group was detected after this experiment.…”

Section: Resultsmentioning

confidence: 92%

The disulfide bridges of the immunoreactive forms of human pancreatic stone protein isolated from pancreatic juice

Rouimi

Bonicel

et al. 1988

FEBS Letters

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Following the complete sequence elucidation of human pancreatic stone protein (immunoreactive form PSP S1 isolated from pancreatic juice) [(1987) Eur. J. Biochem. 168, 201-207], the location of the three S-S bridges of the protein was investigated. The cystine-containing peptides, detected after the separation of the peptic or chymotryptic digests on SP-Sephadex or Sephadex G-50, were submitted to Edman degradation and/or to oxidation. The cysteic peptides after separation on SP-Sephadex or Sephadex G-50 were characterized by their amino acid compositions. The pairing of the half-cystines: Cys 3-Cys 14, Cys 31-Cys 129 and Cys 104-Cys 121 was determined. The same experiments carried out with PSP $2-5 (other immunoreactive forms) gave an identical characterization.Disulfide bridge; Pancreatic stone protein; (Pancreatic juice, Human)

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