Why this thyroid enzyme doesn't need a special selenium amino acid
Mutation of the Secys residue 266 in human type 2 selenodeiodinase alters 75Se incorporation without affecting its biochemical properties.
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
Surprising Findings
Eliminating selenium-75 incorporation did not reduce deiodination activity.
All known deiodinases were thought to require selenocysteine for catalysis—this is the first evidence that one can function without it, contradicting decades of biochemical dogma.
Practical Takeaways
Don't assume all thyroid supplements need high selenium—focus on overall nutrient balance instead.
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
Surprising Findings
Eliminating selenium-75 incorporation did not reduce deiodination activity.
All known deiodinases were thought to require selenocysteine for catalysis—this is the first evidence that one can function without it, contradicting decades of biochemical dogma.
Practical Takeaways
Don't assume all thyroid supplements need high selenium—focus on overall nutrient balance instead.
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Claims (2)
The body converts the thyroid hormone T4 into its active form, T3, using enzymes that require selenium as a component.
Changing a specific amino acid in the human type 2 deiodinase enzyme reduces its ability to take up selenium-75 in laboratory-grown human cells, but does not change its ability to remove iodine from thyroid hormones, suggesting this amino acid is not required for the enzyme's core function in this setting.