The Basic Amino Acids of Serum Proteins (orosins)

We have recently pointed out that even when the amount and ratio of the serum albumin and globulin are greatly changed, the proportion of the basic amino acids, yielded by hydrolysis of the total coagulable serum protein, is constant (l-3). This observation has led us to suggest (3) that instead of the protein of mammalian serum consisting of albumin and globulin, it is composed of two or more unstable coprecipitation systems (4) in mutual equilibrium.’ However much these coprecipitation systems may differ among themselves in physical (6) and chemical characteristics, their sum always has a relatively constant basic amino acid “anlage.” In order to facilitate reference to that component of the serum which shows this relatively constant proportion in the basic amino acids, I wish to propose the term “orosin” (from the Greek, dp6s, serum), to designate the total coagulable protein of the serum (7,s). Orosin is the tissue protein derived from blood plasma which has a constant basic amino acid “anlage.” Serum albumins and globulins are in turn derived from orosin by physicochemical treatment and are therefore interdependent and not, as was heretofore believed, independent protein systems.