| A protein's native conformation is the shape it is supposed to assume after folding. That is, the native conformation is the useful shape of the protein, the shape in which it can catalyze whatever reaction it's involved in, or complete whatever other function it has. It is also the protein's lowest energy state, which it seeks out due to the laws of thermodynamics. Anfinsen's Dogma states that each protein, each group of amino acids held together with peptide bonds, has its own unique native conformation that it will seek out in absence of interfering factors.
There may be errors in finding a native conformation, due to heat or interference from other molecules. These often result in at best non-functioning proteins, and at worst dangerous prion-like proteins or Alzheimer's-like plaques. Chaperone enzymes exist to make sure that such errors in finding native conformation don't take place during a protein's folding.
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