The reaction of iodate with cystine and with insulin

Gorin, George; Godwin, Walter E.

doi:10.1016/0006-291x(66)90585-7

Cited by 10 publications

(6 citation statements)

References 5 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The strongest evidence for removal of inactivation seems to be the fundamentally altered voltage dependence of the open state. The iodate effect may be the final result of a cleavage of S-S bonds (Gorin & Godwin, 1966) in the Na § channel protein and, in this respect, is remarkable as it developed under experimental conditions not fitting the pH optimum of this chemical reaction. Iodate-modified Na + channels terminate their conducting state like other noninactivating Na § channels by a highly voltagesensitive transition into a closed, nonabsorbing configuration.…”

Section: Discussionmentioning

confidence: 99%

“…Cytoplasmically localized amino acid chains supposed to be adjacent to the domains of the alpha-subunit and to form connecting loops (Catterall, 1986):may be another target. Iodate, as well as bromate~ reacts preferentially with S-S bonds between cysteine molecules (Gorin & Godwin, 1966), while glutaraldehyde, the other chemical modifier studied, reacts with e-amino groups of lysine, thereby crosslinking them to neighboring amide, guanidyl and imidazole groups in order to form a Schiff base. Other but less likely reactions would be an oxidation of lysine by iodate and a chemical modification of cysteine by glutaraldelayde.…”

Section: Discussionmentioning

confidence: 99%

“…Iodate belongs to a group of oxidant protein modifiers (Gorin & Godwin, 1966) and is known from earlier Na § current measurement in voltageclamped axons to irreversibly elim,~nate Na § inactivation when applied internally (Stfimpfli, 1974). The main goal of the present experiments was to analyze the effect of iodate and related agents on the singlechannel level in order to characterize the elementary properties of chemically modified Na + channels.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Gating in iodate-modified single cardiac Na+ channels

1989

View full text Add to dashboard Cite

Elementary Na+ currents were recorded at 19 degrees C during 220-msec lasting step depolarizations in cell-attached and inside-out patches from cultured neonatal rat cardiocytes in order to study the modifying influence of iodate, bromate and glutaraldehyde on single cardiac Na+ channels. Iodate (10 mmol/liter) removed Na+ inactivation and caused repetitive, burst-like channel activity after treating the cytoplasmic channel surface. In contrast to normal Na+ channels under control conditions, iodate-modified Na+ channels attain two conducting states, a short-lasting one with a voltage-independent lifetime close to 1 msec and, likewise tested between -50 and +10 mV, a long-lasting one being apparently exponentially dependent on voltage. Channel modification by bromate (10 mmol/liter) and glutaraldehyde (0.5 mmol/liter) also included the occurrence of two open states. Also, burst duration depended apparently exponentially on voltage and increased when shifting the membrane in the positive direction, but there was no evidence for two bursting states. Chemically modified Na+ channels retain an apparently normal unitary conductance (12.8 +/- 0.5 pS). Of the two substates observed, one of them is remarkable in that it is mostly attained from full-state openings and is very short living in nature; the voltage-independent lifetime was close to 2 msec. Despite removal of inactivation, open probability progressively declined during membrane depolarization. The underlying deactivation process is strongly voltage sensitive but, in contrast to slow Na+ inactivation, responds to a voltage shift in the positive direction with a retardation in kinetics. Chemically modified Na+ channels exhibit a characteristic bursting state much shorter than in DPI-modified Na+ channels, a difference not consistent with the hypothesis of common kinetic properties in noninactivating Na+ channels.

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Gating in iodate-modified single cardiac Na+ channels

1989

View full text Add to dashboard Cite

show abstract

“…We attempted oxidative cleavage of disulfide bonds using sodium iodate to assist in the determination of intramolecular disulfide linkages or to verify the results from the partial reduction. The protein was treated with 0.1 M sodium iodate in 0.1 N HCl for various times (0-60 min) to selectively cleave any susceptible disulfide bond(s) (Gorin & Godwin, 1966;Lundblad, 1991). Although oxidation reaction using periodate or performic acid results in complete cleavage of disulfide linkages, sodium iodate mildly reacts with proteins, resulting in selective cleavage of the particular disulfide bonds.…”

Section: Methodsmentioning

confidence: 99%

Glial Cell Line-Derived Neurotrophic Factor: Selective Reduction of the Intermolecular Disulfide Linkage and Characterization of Its Disulfide Structure

et al. 1996

View full text Add to dashboard Cite

Glial cell line-derived neurotrophic factor is a protein known to enhance the survival of dopaminergic neurons against several neurotoxins. It has been shown to have therapeutic potential in the treatment of Parkinson's disease and other neurodegenerative diseases. We have determined the inter- and intramolecular disulfide linkages of the dimeric molecule by a combination of direct peptide analysis and peptide analysis after either partial reduction or partial oxidation of the protein. Under an acidic condition, the interchain disulfide bond was selectively cleaved with tris(2-carboxyethyl)phosphine, revealing that Cys101 was involved in the intermolecular disulfide linkage. Three other disulfides, Cys68-Cys131, Cys72-Cys133, and Cys41-Cys102, were identified as intramolecular linkages. The determined disulfide structure is highly homologous to that of transforming growth factor beta 2. Since one intramolecular disulfide points through a ring consisting of eight amino acid residues based on the similarity with transforming growth factor beta 2, the disulfide-linked peptides were not purified by conventional methods. Only the peptides from an N-terminal region (residues -1 to 37) were liberated by proteolytic treatment with trypsin or endoproteinase Lys-C, resulting in a stable cystine-knot protein.

show abstract

“…Iodate and H202 cause a small shift of the h,,(E) curve in the hyperpolarizing direction. There is not much known about the effects (and side effects) of iodate on amino acid side chains except that this reagent oxidizes SH-groups and disulfide bonds (Gorin and Godwin, 1966). H202 readily oxidizes methionine and sulfhydryl groups (see Means and Feeney, 1971).…”

Section: No Effect Of Tyrosine and Arginine-reactive Reagentsmentioning

confidence: 99%

Effects of some chemical reagents on sodium current inactivation in myelinated nerve fibers of the frog

Rack¹,

Rubly²,

Waschow³

1986

Biophysical Journal

View full text Add to dashboard Cite

The effect of several chemical reagents on the sodium current was studied in voltage-clamped single nerve fibers of the frog. The oxidants halazone and hypochlorous acid drastically inhibited inactivation. Their effect was similar to that of chloramine T (Wang, 1984a). The curve relating the steady-state inactivation parameter h infinity to the conditioning potential E became nonmonotonic after treatment with the oxidants, i.e., dh infinity/dE greater than 0 for E greater than -20 mV. By contrast, the oxidants periodate, iodate, and hydrogen peroxide (applied for the same time, but at higher concentrations) merely produced a parallel shift of the h infinity(E) curve to more negative values of membrane potential. Diethylpyrocarbonate, a reagent that preferentially modifies histidine groups, had one marked effect: a strong shift of the h infinity(E) curve to more negative values of membrane potential. Almost no effect was observed after application of the tyrosine-reactive reagent N-acetylimidazole. Similarly, the arginine-reactive reagent glyoxal had only minor effects on the Na permeability. The results suggest that methionine is not critically involved in the kinetics of Na current inactivation. Similarly, an essential tyrosine or arginine residue seems to be unavailable to chemical reagents from outside on the frog node of Ranvier. Deduced from the reactivities of (some of) the reagents used, modification of membrane lipids is a tentative explanation for the effects observed on inactivation kinetics.

show abstract

The reaction of iodate with cystine and with insulin

Cited by 10 publications

References 5 publications

Gating in iodate-modified single cardiac Na+ channels

Gating in iodate-modified single cardiac Na+ channels

Glial Cell Line-Derived Neurotrophic Factor: Selective Reduction of the Intermolecular Disulfide Linkage and Characterization of Its Disulfide Structure

Effects of some chemical reagents on sodium current inactivation in myelinated nerve fibers of the frog

Contact Info

Product

Resources

About