Protein structure characterized by the combination of different proteins that all together are required for protein function in which level of protein structure?

Quaternary structure

Explanation:

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A protein can be characterized by:

Primary structure: it is the linear sequence of amino acids.

Secondary structure: The amino acid sequence is folded by intermolecular interactions.

Tertiary structure: A greater folding of amino acids is observed by intermolecular interactions and disulfide bridges.

Quaternary structure: Two or more chains of folded amino acids join to form a new, more complex structure.

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