Protein found in a biological system with a unique three-dimensional structure

Protein found in a biological system with a unique three-dimensional structure and biological activity is called a native protein.When a protein in its native form, is subjected to a physical change like change in temperature or a chemical change like, change in pH, denaturation of protein takes place. Explain the cause.
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What is the effect of denaturation on the structure of proteins?

Due to physical change like change in temperature and chemical change, like change in pH, hydrogen bonds in proteins are disturbed.
Due is this globules unfold and helix gets uncoiled and therefore, protein loses its biological activity. This is known as denaturation of proteins.