scholarly journals THE ROLE OF SULFHYDRYL GROUPS IN THE BLEACHING AND SYNTHESIS OF RHODOPSIN

1952 ◽  
Vol 35 (5) ◽  
pp. 797-821 ◽  
Author(s):  
George Wald ◽  
Paul K. Brown
Keyword(s):  
Protein Denaturation ◽  
Sulfhydryl Groups ◽  
Amino Groups ◽  
Hydrogen Atoms ◽  
Sulfhydryl Reagents ◽  
Excitation Process ◽  
Sh Groups ◽  
Sulfhydryl Compound

The condensation of retinene1 with opsin to form rhodopsin is optimal at pH about 6, a pH which favors the condensation of retinene1 with sulfhydryl rather than with amino groups. The synthesis of rhodopsin, though unaffected by the less powerful sulfhydryl reagents, monoiodoacetic acid and its amide, is inhibited completely by p-chloromercuribenzoate (PCMB). This inhibition is reversed in part by the addition of glutathione. PCMB does not attack rhodopsin itself, nor does it react with retinene1. Its action in this system is confined to the —SH groups of opsin. Under some conditions the synthesis of rhodopsin is aided by the presence of such a sulfhydryl compound as glutathione, which helps to keep the —SH groups of opsin free and reduced. By means of the amperometric silver titration of Kolthoff and Harris, it is shown that sulfhydryl groups are liberated in the bleaching of rhodopsin, two such groups for each retinene1 molecule that appears. This is true equally of rhodopsin from the retinas of cattle, frogs) and squid. The exposure of new sulfhydryl groups adds an important element to the growing evidence that relates the bleaching of rhodopsin to protein denaturation. The place of sulfhydryl groups in the structure of rhodopsin is still uncertain. They may be concerned directly in binding the chromophore to opsin; or alternatively they may furnish hydrogen atoms for some reductive change by which the chromophore is formed from retinene1. In the amperometric silver titration, the bleaching of rhodopsin yields directly an electrical variation. This phenomenon may have some fundamental connection with the role of rhodopsin in visual excitation, and may provide a model of the excitation process in general.

New approaches to the role of sulfhydryl groups in silver stainability of protein in grasshopper chromosomes

Genome ◽  
1988 ◽  
Vol 30 (2) ◽  
pp. 133-137 ◽  
Author(s):  
J. de la Torre ◽  
J. L. Bella ◽  
C. López-Fernandez ◽  
J. Gosálvez
Keyword(s):  
Silver Staining ◽  
Chemical Nature ◽  
Germ Line ◽  
Staining Technique ◽  
Sulfhydryl Groups ◽  
Sh Groups ◽  
New Approaches ◽  
Silver Staining Technique ◽  
Reduced State

Silver staining in somatic and germ line cells of the grasshopper Arcyptera fusca has been analyzed after a standard silver staining technique was used with pretreatments that included dithiothreitol and β-mercaptoethanol as reagents to maintain —SH groups in the reduced state. The results show that in some tissues, these pretreatments improve not only the silver staining of nucleolar masses but also the recognition of other silver spots associated with the chromatin. These observations are similar to those previously described for the effect of double-strength standard saline citrate on silver staining. The possible chemical nature of the protein groups responsible for the differential silver stainability and the role of saline citrate in the modification of argyrophylic proteins suggested previously are briefly discussed.Key words: Orthoptera, silver staining, sulfhydryl groups.

Investigations into the role of sulfhydryl groups in the mechanism of action of the nitrates

1982 ◽  
Vol 60 (10) ◽  
pp. 1261-1266 ◽  
Author(s):  
J. A. Moffat ◽  
P. W. Armstrong ◽  
G. S. Marks
Keyword(s):  
Smooth Muscle ◽  
Vascular Smooth Muscle ◽  
Mechanism Of Action ◽  
Active Site ◽  
Sulfhydryl Reagents ◽  
Response Curves ◽  
Sh Groups ◽  
Nitrobenzoic Acid ◽  
Sh Group

The mechanism by which nitroglycerin (GTN) initiates relaxation in vascular smooth muscle is not known. According to one hypothesis a specific nitrate receptor exists with a key sulfhydryl (SH) group in the active site. The current study was performed with sulfhydryl reagents in helical strips of the canine medial saphenous vein from 20 dogs to examine the role of the SH group in the action of GTN. The reagents used were 5,5′-dithiobis(2-nitrobenzoic acid) (DTNB) and p-chloromercuribenzoate (PCMB) which bind to and inactivate SH groups, and dithiothreitol (DTT), an SH reducing agent. It was anticipated that DTNB and PCMB would decrease the sensitivity to GTN while DTT might increase the sensitivity to GTN. Treatment of strips with PCMB and DTNB did not alter the dose–response curves for GTN. In contrast, following DTT treatment (1 × 10−4 M) the maximum response to GTN (10−5 M) was significantly reduced from 80.3% ± 4.0 (SD) in control strips to 46.9% ± 4.4 (SD) in the treated strips. These data suggest that relaxation induced by GTN in vascular smooth muscle occurs by a mechanism other than interaction with membrane SH groups.

scholarly journals ON THE ROLE OF VIRUS SULFHYDRYL GROUPS IN THE ATTACHMENT OF ENTEROVIRUSES TO ERYTHROCYTES

1960 ◽  
Vol 112 (3) ◽  
pp. 455-478 ◽  
Author(s):  
Lennart Philipson ◽  
Purnell W. Choppin
Keyword(s):  
Virus Particle ◽  
Human Erythrocytes ◽  
Hemagglutinating Activity ◽  
Sulfhydryl Groups ◽  
Present Communication ◽  
Sulfhydryl Reagents ◽  
Thiol Compounds ◽  
Virus Particles ◽  
Receptor Sites

Many animal viruses possess the ability to agglutinate erythrocytes. In most but not all cases hemagglutination is due to the virus particle itself, and appears to result from the mechanical bridging of two or more erythrocytes by virus particles which attach to receptor sites on each erythrocyte (1, 2). Thus, attachment of virus particles to erythrocytes is a prerequisite for hemagglutination, and prevention of absorption of virus prevents hemagglutination. Among the enteroviruses, many ECHO viruses and some strains of Coxsackie B3 virus agglutinate human erythrocytes (3-7), and the evidence indicates that hemagglutination is due to the virus particle itself (3, 5, 6). The precise mechanism of attachment of enteroviruses to cells is unknown. Chymotrypsin treatment of erythrocytes prevents the absorption of some ECHO viruses (8). This suggests that the receptor sites on the erythrocyte may be at least in part protein in nature. The present communication is concerned with the mechanism of attachment of enteroviruses to cells. It is shown that sulfhydryl reagents block the hemagglutinating activity of enteroviruses. Treated virus fails to absorb to erythrocytes. Thiol compounds restore the hemagglutinating activity of enteroviruses treated with mercaptide-forming sulfhydryl reagents. The effect of sulfhydryl reagents on the infectivity of some enteroviruses is also described.

scholarly journals Role of membrane sulfhydryl groups in stimulation of renin secretion by sulfhydryl reagents

1991 ◽  
Vol 39 (5) ◽  
pp. 867-873 ◽  
Author(s):  
Philip S. Doh ◽  
Cheol Joo Lee ◽  
Peter M. Hwang ◽  
Kyung Woo Cho ◽  
Thomas W. Honeyman ◽  
...  
Keyword(s):  
Sulfhydryl Groups ◽  
Renin Secretion ◽  
Sulfhydryl Reagents ◽  
Stimulation Of
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