Insulin possesses two polypeptide chains denoted A and B that are linked by disulfide bonds. Upon denaturation by reduction of the SH groups of insulin, followed by reoxidation, only 7%  of the hormone activity is recovered. This is the level of activity expected for random pairing  of cysteine residues to form disulfide bonds. How can these data be reconciled with the hypothesis that the amino acid sequence directs protein folding?

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Metabolic pathways

Metabolism is defined as the group of life-supporting, enzyme-mediated chemical reactions in organisms. A metabolic pathway is a set of these chemical reactions that involve anabolism (synthesis of complex biomolecules) and catabolism (breakdown of biomolecules into small molecules) that occur inside a cell. Metabolites are the reacting substances, products, and intermediate substances of an enzymatic process that are altered by a series of chemical events catalyzed by enzymes.