Disulfide Bond Formation

[dukedevils25]

Can disulfide bonds form in oxidizing conditions naturally or do they require the ENZYME Protein Disulfide Isomerase......that is if i just drop two cysteines in an oxidizing atmosphere, will disulfide bonds form or do you need the protein disulfide isomerase?

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[PiBond]

If you were to just drop two cysteins into solution I don't think a disulfide bond would form unless there was an enzyme present due to the need to orient the molecules properly for the reaction--I think entropy wouldn't allow it either without the presence of an enzyme and some sort of coupling reaction. However, disulfide bond formation in protein structure doesn't need a enzyme (to my knowledge) and is contingent upon primary structure.

 

[boaz]

Can disulfide bonds form in oxidizing conditions naturally or do they require the ENZYME Protein Disulfide Isomerase......that is if i just drop two cysteines in an oxidizing atmosphere, will disulfide bonds form or do you need the protein disulfide isomerase?

Recall that the function of an enzyme, which is a biological catalyst, is to increase the RATE at which a reaction occurs. In other words, without the enzyme the reaction will EVENTUALLY occur, but it can take hours, days, or millions of years. Disulfide bonds will form, but it will take a very long time without a catalyst.

If you were to just drop two cysteins into solution I don't think a disulfide bond would form unless there was an enzyme present due to the need to orient the molecules properly for the reaction--I think entropy wouldn't allow it either without the presence of an enzyme and some sort of coupling reaction. However, disulfide bond formation in protein structure doesn't need a enzyme (to my knowledge) and is contingent upon primary structure.

It does require an enzyme. It's called protein disulfide isomerase.

It is also SPECIFIC as to which cysteines it works on. Many disulfide bonds may be thermodynamically possible within one polypeptide; it is the enzyme that determines which disulfide bonds are present in the final tertiary structure of the protein.