E.coli can make Disulphide bonds if you ask it nicely.

Human protein, expressed in NEB SHuffle cells, correctly folded, crystallised, solved, etc.

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Electron density around a Disulphide bond – which E.coli cannot make in their cytoplasm normally – unless you tinker with a few genes here and there.

The Disulphide is the bond between the two green sulphur atoms in the centre of the image

EDIT: Click to see the picture more clearly – I don’t know what WP has done to it, but it should look crisper than that.