Some Phosphorus Compounds of Milk

Abstract

A preliminary study of the possible relation of the mode of combination of the P in phospho-proteins like caseinogen in milk or vitellin of egg to their existence in the natural foodstuffs of the new born animal. Since pepsin liberates no inorganic P from caseinogen, and trypsin only after long time or at high concentration, and since both these alimentary enzymes produce intermediate organic P compounds which are diffusible, the possibility exists that the young animal may absorb organic P. As regards the structure of caseinogen, the production of different organic compounds by trypsin and pepsin suggests different points of attack on the molecule; hydrolysis of phosphopeptone (intermediate organic P compound produced by action of trypsin on caseinogen) but not of caseinogen by bone and kidney phosphatases suggests linkages in the former similar to those existing in hexose-mono- and hexosedi-phosphoric acids and absence of these linkages in caseinogen; different actions of rat bone and rabbit kidney phosphatase preparations on phosphopeptone suggests that the latter is a mixture of several organic P compounds.