Question

Tyrosine absorbs maximally at 290 nm. A 0.2162 g sample containing some amount of Tyrosine was placed into a 250.0 mL volumetric flask and diluted to the mark. This solution had an absorbance of 0.118 (at 290 nm) in a 2.00 cm pathlength cell. A sample of pure Tyrosine (MW - 1818 g/mole) weighing 12.4 mg was dissolved in a 100.0 mL of solution. A 10.0 mL aliquot of this 100.0 mL solution was added to a 250.0 mL flask and diluted to the mark. This last diluted sample had an absorbance of 0.473 at 290 nm in a 1.00 cm cell. Calculate the weight percent of Tyrosine in the sample. Assume no other compounds in the sample, except Tyrosine, absorb at 290 nm.A. 0.14 %

B. 0.069 %
C. 0.028 %
D. 0.040 %
E. 1.80 %
F. 2.63 %

Answer 1

B. 0.069 %

Step-by-step explanation:

It should be initially noted in this answer in particular that, the amino acids tryptophan and tyrosine have a very precise 280 nm absorption rate, which allows a direct A280 size of protein concentration. The 280 nm UV absorbance rate is regularly utilized to approximate protein concentration in laboratories due to its simplistic nature, its affordability and also the ease of usage.

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