There are more than four elements in proteins : Carbon, hydrogen, oxygen, nitrogen, sulphur and selenium being the main six. It is not clear where you got the number 4 from and therefore which four you are asking about.
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The chemical formula of the compound shows the ratio of the atoms of elements in a compound. This must not be confused with the ratio of their masses.
The ratio depends on the compound.
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carbohydrates, lipids, proteins and nucleic acids
K:H:P:O = 1:2:1:4