The Combination of Deaminized Gelatin with Hydrochloric Acid

1. The analysis of isoelectric gelatin by the Van Slyke method indicates 0.00040 equivalents of amino N per gm. gelatin. 2. If deaminized gelatin is prepared without heating, the product contains less nitrogen than the original gelatin by an amount equal to 0.00040 equivalents N per gm. protein. 3. Deaminized gelatin, prepared either with or without heating, contains no amino nitrogen detectable with certainty by either the Van Slyke or the formol titration method. 4. The isoelectric point of deaminized gelatin prepared without heating is at pH 4.0. 5. The maximum combining capacity of this protein for HCl is 0.00044 equivalents per gm. 6. The maximum combining capacity of gelatin for HCl should be corrected to 0.00089 equivalents per gm. 7. The difference between these maximum combining capacities, 0.00045, is nearly equivalent to the loss in amino or total nitrogen occurring in the deaminizing reaction. 8. This equivalence constitutes a new indication that the combination of protein with acid is chemical combination.