What is the average nitrogen content of protein?

What is the average nitrogen content of protein?

• A. 14%
• B. 18%
• C. 16%
• D. 20%

Answer: (C)

Proteins are made up largely of amino acids, which contain nitrogen in their amino groups. On average, nitrogen accounts for about one-sixth of a protein’s mass, so the typical nitrogen content is around 16% by weight. This standard value is why nitrogen measurements are often converted to protein using a factor of 6.25 (protein ≈ nitrogen × 6.25). While individual proteins can vary a bit, 16% is the commonly accepted average. The other numbers don’t reflect the usual average: they would indicate notably different nitrogen proportions than what is typically seen in most proteins.

Proteins are made up largely of amino acids, which contain nitrogen in their amino groups. On average, nitrogen accounts for about one-sixth of a protein’s mass, so the typical nitrogen content is around 16% by weight. This standard value is why nitrogen measurements are often converted to protein using a factor of 6.25 (protein ≈ nitrogen × 6.25). While individual proteins can vary a bit, 16% is the commonly accepted average. The other numbers don’t reflect the usual average: they would indicate notably different nitrogen proportions than what is typically seen in most proteins.