Minimum molecular weight ratio proteins

Conversion of the relative ratios of amino acids into an estimate of actual composition requires some additional information concerning the protein s molecular weight for example, an analysis giving relative ratios of Ala (1.0), Gly (0.5), and Lys (2.0) could correspond to composition Ala2-Gly-Lys4 or any multiple thereof. The required information is usually available, and in any case, an estimation of composition based on a minimum molecular weight of the protein is always possible. 

When total iron and non-heme iron in adrenodoxin were determined with o-phenanthroline all the iron existed as non-heme iron and was extractable with 5% trichloroacetic acid. The ratio of iron to protein on a biuret basis was 109 mp. atoms of iron per mg of protein. Based on the dry weight of adrenodoxin, the ratio was 147 mp. atoms of iron per mg protein. The minimum molecular weight per iron atom would be 6,800. 

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