A newly isolated protein was found to contain 0.533% tyrosine by weight upon amino acid analysis.
(a) What is the minimum molecular weight for the protein (assuming only one Tyr residue per protein molecule)?
(b) Gel filtration of the protein gae an estimated molecular weight of 9.0 x 104 g/mol. How many Tyr residues are in the protein?
The molar mass of a single tyrosine residue is 181g/mol. However, if this amino acid is in the middle of the peptide sequence, water will be removed through the condensation process, reducing the contributed mass to 163g/mol. The smallest possible protein for this problem would need to contain one tyrosine residue. If that's the case, 163 would be 0.533% of the protein's molecular weight.