. Cell chemistry; a collection of papers dedicated to Otto Warburg on the occasion of his 70th birthday. Warburg, Otto Heinrich, 1883-; Biochemistry. 58 F. F. NORD, M. BIER VOL. 12 (1953) difference in electrophoretic mobility, calcium ions cause a change in the appearance of the electrophoretic pattern. Whereas in the absence of calcium trypsin presents patterns characteristic of a homogeneous compound as shown by the photographs in series A, Fig. i, two well-defined peaks appear upon the addition of calcium. We have studied the conditions of maximal separation of the two components. Two fact
. Cell chemistry; a collection of papers dedicated to Otto Warburg on the occasion of his 70th birthday. Warburg, Otto Heinrich, 1883-; Biochemistry. 58 F. F. NORD, M. BIER VOL. 12 (1953) difference in electrophoretic mobility, calcium ions cause a change in the appearance of the electrophoretic pattern. Whereas in the absence of calcium trypsin presents patterns characteristic of a homogeneous compound as shown by the photographs in series A, Fig. i, two well-defined peaks appear upon the addition of calcium. We have studied the conditions of maximal separation of the two components. Two factors are found to influence the separation of the two components: pH and concentration of calcium. In Fig. i, series B and C, the electrophoretic patterns obtained in the presence of and ^I CaCla respectively are presented. It is evident that at the lower concentration of the calcium ions the sepa- » ration of the two components is not yet complete. A further ^^%^^^ increase of concentration of calcium ions gives rise to no HL-J2^S other changes in pattern and therefore the concentration of 0-033 ^^ was applied in the comparison of all chlorides of divalent cations. To study the effect of monovalent cations a concentration of M was chosen to keep the ionic strength constant. Because of the relatively high require- ments of calcium ion concentration, advantage could not be taken of the observed better separation of electrophoretic components at very low ion concentrations^'^^. As expected from the dissociation curves of trypsin, the separation of the two components is best evidenced between pH 4 and 5. At pH and the two peaks remain partially superimposed, even after prolonged electrophoresis. In Table I are listed all the cations, applied as chlorides, the effect of which on the electrophoretic patterns of trypsin ^" was investigated. Besides calcium, only manganese and cadmium cause a separation of peaks to occur, whereas all other cations give ris
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