Determinations of various forms of nitrogen in bovine flesh, including the products of hydrolysis of some of the proteins
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When Hausmann introduced his method for nitrogen distribution into protein analysis, he opened the way for great progress in that line of investigation. Winterstein later showed that phoaphotungstic acid would also precipitate cystine. Van Slyke improved the gasometric method of Sachse and Kormann for the determination of amino nitrogen and from these methods of analysis worked out a combination of them for determining arginine, histidine, lysine, and cystine in proteins. Several improvements in the method, such as removal of the phosphotungstic acid from the precipitate of the bases by shaking it out with amyl alcohol and ether by Van Slyke and the boiling of the bases with alkali of lower concentration for determination of the arginine by Plimmer have recently been published. The method has been widely used in the analysis of various proteins, tissues, foods and feeding stuffs. For this study a number of beef proteins were analyzed according to the Van Slyke method. The proteins used represent the fractions of the flesh as developed by Grindley. The cold water insoluble protein is a mixture of stroma and plasma proteins and contains albuminoids, and nucleo proteins. The cold water soluble, heat coagulable fraction is a mixture of plasma protein, the albumins and globulins flesh. On page 40 is given an analysis of the flesh of a newborn calf showing just what part of the flesh these fractions represent. A description of the samples and the method of preparing them is given in a later section.