A coenzyme differs from a cofactor in that a coenzyme is

  • A. an inorganic metal ion
  • B. an organic molecule, often derived from a vitamin
  • C. part of the polypeptide chain
  • D. a type of substrate

Explanation

NAD, FAD and coenzyme A are organic helpers built from niacin, riboflavin and pantothenic acid respectively, whereas cofactors such as zinc and magnesium ions are inorganic. A helper bound tightly and permanently is called a prosthetic group instead. This is why vitamin deficiencies cause such widespread metabolic effects.

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