Acute toxic liver injury. nicotinamide-adenine dinucleotide-pyrophosphorylase activity of nuclei isolated from rat liver in heliotrine and in dimethylnitrosamine poisoning.

2. The nunmber of reactive SH groups/molecule in the haemoglobins studied approximate either to 2 or to 4. 3. The behaviour of the reactive SH groups differs from that of cysteine in three ways: (a) the rate of reaction of heavy-metal ions with the reactive SH groups is slower than with cysteine; (b) thiosulphate interferes with the reaction between Ag+ ions and the reactive SH groups of human haemoglobin, but not with cysteine; (c) the acid-base-titration curves of human haemoglobin in the presence and absence of phenylmercuric hydroxide suggest that the reactive SH groups are not ionized at pH values less than 10.