On the Action of Coagulating Enzymes on Caseinogen.

Hammarsten [1872, 1874, 1877] first demonstrated that the rennin action on caseinogen was specific and independent of the action of the calcium salts. His explanation was that the caseinogen molecule was split up into a large molecule (Ruase) and a smaller one (Molkeneiweiss). The "Kiise" was rendered insoluble by the presence of soluble calcium salts and formed the clot. Since then little has been done to determine the chemistry of the clotting process, and our knowledge of this branch -of the subject has up till recently been untouched by investigators. The recent literature contains views which contradict the theory advanced by Hammarsten. Schryver [1913, 1 and 2] and Mellanby [1913] both consider that the rennin clot is probably a combination of enzyme and protein, and Schryver states definitely that rennin alone causes no proteoclastic change. Bosworth [1913] has found that the rennin does not split off any nitrogen from the caseinogen which remains in solution when the casein is precipitated by dilute acetic acid. The protein molecule has therefore undergone no cleavage into its components. This, considered in connection with the results of his earlier work with van Slyke [1913], leads him to believe that the ferment breaks up the caseinogen molecule into two molecules of casein each halfthe size of the original molecule. In the case of basic calcium caseinogenate (containing 4 equivalents of calcium) the casein produced is soluble in water but is rendered insoluble By the presence of small quantities of calcium chloride. The caseinogenate containing two equivalents of calcium gives a casein insoluble in water'.