oxidation number for sulfur in proteins

[bored]

this might be a stupid question.. but
can someone tell me the oxidation number for S in proteins before and after disulfide linkage formation and how they got that. Thanks.

so before oxidation, its
R-SH + R-SH

and after oxidation, the S combines to form

R-S-S-R

I need to know how one gets oxidation number for the S in both conditions. Thanks

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[AureatEagle]

this might be a stupid question.. but
can someone tell me the oxidation number for S in proteins before and after disulfide linkage formation and how they got that. Thanks.

so before oxidation, its
R-SH + R-SH

and after oxidation, the S combines to form

R-S-S-R

I need to know how one gets oxidation number for the S in both conditions. Thanks

You do not need to know how to calculate the oxidation state of elements in complex organic compounds for the MCAT.

But if you're curious, the S in an RSH group has a -2 oxidation state since the R and H have +1 oxidation states and the group is overall neutral (this is analogous to the oxidation states of each atom in ROH). The S's in RSSR each have a -1 oxidation state since each R has a +1 oxidation state, and the molecule overall is neutral. Thus, when S makes a disulfide bridge, it is oxidized.

The much easier way to tell oxidation/reduction (since we're dealing with organic molecules) is to notice that the S loses an H in the process of making the bridge. Losing H = atom was oxidized.

 

[Jepstein30]

You do not need to know how to calculate the oxidation state of elements in complex organic compounds for the MCAT.

But if you're curious, the S in an RSH group has a -2 oxidation state since the R and H have +1 oxidation states and the group is overall neutral (this is analogous to the oxidation states of each atom in ROH). The S's in RSSR each have a -1 oxidation state since each R has a +1 oxidation state, and the molecule overall is neutral. Thus, when S makes a disulfide bridge, it is oxidized.

The much easier way to tell oxidation/reduction (since we're dealing with organic molecules) is to notice that the S loses an H in the process of making the bridge. Losing H = atom was oxidized.

Yea, when dealing with organic chem stuff.. just know that:

reduction = gain of H, loss of O
oxidation = gain of O, loss of H

Don't need to know how to calculate oxidation number.. leave that to gen chem

 

[bored]

Thanks both