Why did protein in buiret turn dark blue, then back to clear when heated?

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Em - LEE

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If protein is put into a buiret reagent and it turns dark blue, but then turns back to clear when heated, does this mean that the protein was burned away? Were the peptide bonds broken, somehow, through heating? Why did this occur?
 
Buirets solution turns from BLUE to VIOLET, not to dark blue, check you have the correct solution.

Anyway heat denatures the protein. Buirets tests for peptide bonds, which are broken by the heat energy.

Edit: also jamesm557whatever.. above me is wrong. Breaking the tertiary structure of a protein does not cause it to fail a Buirets test. Some protein chains have no tertiary structure (such as individual strands in collagen), but will cause a colour change.
He's probably thinking of enzymes cacking up due to changes in the active site.
 
almost. the protein was denatured which mean it was unfolded into a unstructured string of amino acids.

as a proteins structure shows function if it no longer has a 3d structure it doesnt have any function. this is the reason why meat turns brown when cooked. it is denatured haemoglobin and myoglobin.

it is not broken in any way. just unfolded
 
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