The irreversibility of the deamination of threonine in the rabbit and rat

Abstract

Various amino acids were isolated from protein of muscle and internal organs of rabbits and rats fed glycine containing excess N15. The glycine, serine, glutamic acid, arginine and tyrosine contained varying concns. of N15. Since threonine, like lysine, had no excess N15, it was assumed not to take part in the reversible transfer of N observed with other amino acids. The fact that glycine and serine isolated contained similar proportions of N15, was taken to indicate that the conversion of glycine into serine is very fast.