Daily Rhythm in Tyrosine Concentration in Human Plasma: Persistence on Low-Protein Diets

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Science  03 Nov 1967:
Vol. 158, Issue 3801, pp. 660-662
DOI: 10.1126/science.158.3801.660


The concentration of tyrosine in the plasma of normal males varies diurnally. It is lowest (9.5 ± 0.35 micrograms per milliliter) between 0130 and 0230 hours and rises to a peak of 16.2 ± 0.82 micrograms per milliliter by 1030 hours. This rhythm persists when subjects are maintained for 2 weeks on a diet that is very low in protein.