[Lyophilization protection of hemoglobin by N-acetyltryptophan]

Measurements of methemoglobin content, different oxyphoric powers, oxygen affinity were made on freeze-dryed hemoglobin without protector and in presence of N-acetyl tryptophan and/or alpha-D glucose. These measurements revealed that, at low concentrations, N-acetyl tryptophan offers a better protection than glucose. Moreover, this acetylated amino-acid decreases the oxygen affinity of hemoglobin (Po(2)50 increased). The two protectors do not seem to compete, but present complementary effects.