The determination of acid‐soluble nucleotides in milk by improved enzymic methods: A comparison with the ion‐exchange column chromatography procedure

Enzymic methods have been developed to measure adenosine, cytidine, guanosine, and uridine‐5′‐monophosphates and also total adenine, cytidine, guanine, and uridine nucleotides in cow, goat, sheep, and human milk. Uridine‐diphosphate glucose, uridine‐diphosphate galactose, and orotate have also been measured by specific enzymic methods. There were no significant differences between the values obtained by ion‐exchange column chromatography and enzymic methods. These last procedures were faster, simpler, and less time consuming to perform compared with conventional methods in use at present. Correlations have been established between the nucleotide contents in milk and the optical density of protein‐free milk extracts from different species. Simple mathematical formulae allow estimation, with an error < 5 %, of the nucleotide contents of cow, goat, sheep, and human milk samples, by measuring the optical density of the corresponding protein‐free milk extracts at 250, 260, and 280 nm.