Sulfurtransferase Enzymes Involved in Cyanide Metabolism

1. In the aetiopathogenesis, in Nigerians, of a degenerative neuropathy known as tropical ataxic neuropathy, chronic cyanide intoxication is believed to be the most important factor. The source of the cyanide is cassava (Manihot) and in Nigerian patients, plasma concentration of thiocyanate, a major detoxication product of cyanide, is high.2. Since there is considerable doubt as to whether cyanide is readily released from cassava diet after ingestion, rats were fed on 80 and 100% purupuru (a cassava derivative) diets for periods varying between 6 and 18 months and their plasma thiocyanate levels were studied. Control rats were fed on a normal diet for the same periods.3. Rats fed on the 100% purupuru diet were malnourished. Rats fed on the 80 % purupuru diet appeared normal, although their mean weight was less than the mean weight of rats fed on the normal diet.4. Plasma thiocyanate was significantly higher in rats fed the purupuru diets than in the rats fed on the normal rat diet.5. The concentration of thiosulphate Sulphurtransferase, the enzyme that catalyses the conversion of cyanide into thiocyanate was the same in rats fed on the purupuru diets as in the control rats.6. The results suggest that raised plasma thiocyanate levels found in Nigerian patients with ataxic neuropathy, as in rats fed cassava diet, is the result of detoxication of cyanide, as the concentration of thiocyanate in cassava and most food products eaten by Nigerians is low.

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The effect of temperature on the rate of cyanide metabolism of two woody plants

Chemosphere ◽

10.1016/j.chemosphere.2004.12.020 ◽

2005 ◽

Vol 59 (8) ◽

pp. 1099-1104 ◽

Cited By ~ 30

Author(s):

Xiaozhang Yu ◽

Stefan Trapp ◽

Puhua Zhou ◽

Hao Hu

Keyword(s):

Woody Plants ◽

Effect Of Temperature ◽

Cyanide Metabolism

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Gasotransmitter H2S accelerates seed germination via activating AOX mediated cyanide-resistant respiration pathway

10.1101/2021.10.13.464324 ◽

2021 ◽

Author(s):

Huihui Fang ◽

Ruihan Liu ◽

Zhenyuan Yu ◽

Gang Wu ◽

Yan xi Pei

Keyword(s):

Seed Germination ◽

Alternative Oxidase ◽

Reducing Power ◽

Underlying Mechanism ◽

Terminal Oxidase ◽

Post Translational Modification ◽

Physiological Processes ◽

Activity Of Enzymes ◽

Cyanide Metabolism ◽

Cyanide Resistant Respiration

Hydrogen sulfide (H2S) has been witnessed as a crucial gasotransmitter involving in various physiological processes in plants. H2S signaling has been reported to involve in regulating seed germination, but the underlying mechanism remains poorly understood. Here, we found that endogenous H2S production was activated in germinating Arabidopsis seeds, correlating with upregulated both the transcription and the activity of enzymes (LCD and DES1) responsible for H2S production. Moreover, NaHS (the H2S donor) fumigation significantly accelerated seed germination, while H2S-generation defective (lcd/des1) seeds exhibited decreased germination speed. Further results indicated that the alternative oxidase (AOX), a cyanide-insensitive terminal oxidase, can be stimulated by imbibition, and the expression of AOX genes was provoked lag behind H2S production during germination. Additionally, exogenous H2S fumigation significantly reinforced imbibition induced enhancement of AOX1A expression, and mediated post-translational modification to keep AOX in its reduced and active state, which mainly involved H2S induced increase of the GSH/GSSG ratio and the cell reducing power. Consequently, H2S signaling acts as a trigger to induce AOX mediated cyanide-resistant respiration to accelerate seed germination. Our study correlates H2S signaling to cyanide metabolism, which also participates in endogenous H2S generation, providing evidence for more extensive studies of H2S signaling.

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