= John E. Scott
{disambiguate=enzyme assay researcher}
{c}
<John E. Scott (enzyme assay researcher)> is an <enzyme assay> researcher and coauthor, with <Kevin P. Williams (enzyme assay researcher)>, of guidance on validating <enzyme> preparations. The original byline associates both authors with the BRITE institute at North Carolina Central University when the chapter was prepared.<Validating Identity, Mass Purity and Enzymatic Purity of Enzyme Preparations by John E. Scott and Kevin P. Williams>[Author affiliations and byline, 2012]{ref}
Their methodological contribution separates three questions: is the intended <enzyme> present, what fraction of the <protein> material does it represent, and what fraction of the measured activity actually comes from it? <Protein mass purity> and <enzymatic purity> are different because a small contaminant can contribute disproportionately to an <enzyme assay>.<Validating Identity, Mass Purity and Enzymatic Purity of Enzyme Preparations by John E. Scott and Kevin P. Williams>[Definitions; Interrelationships between Identity, Mass and Enzymatic Purity]{ref}
Consider an invented preparation containing $99$ mass units of the intended <enzyme> and one of a contaminant. If that contaminant produces $100$ times as much assay signal per unit mass, the two components contribute $99$ and $100$ signal units. The intended <enzyme> supplies only $99/199\approx49.7\%$ of the measured signal despite $99\%$ <protein mass purity>.
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