The Effect of Alcohol on the Digestion of Fibrin and Caseinogen by Trypsin

Further Observations on the Digestion of Fibrin and Caseinogen by Trypsin

“…If this assumption of Mellanby and Woolley is correct, however, then the milk coagulating power and the power to hydrolyse both fibrin and caseinogen should presumably be quite parallel in their behaviour. The experiments detailed in the present paper, and those described previously [Edie, 1919], however, tend to show that the digestion of fibrin and of caseinogen, if carried out by one enzyme, involves at least two sets of groups of the enzyme molecule, and therefore cannot be said really to be produced by the same substance in the sense evidently meant by Mellanby and Woolley.…”

“…The activity of the trypsin in their experiments was measured by its power of coagulating calcified milk. Other references to the effect of hydrochloric acid on trypsin at moderate temperatures have been mentioned in a previous paper [Edie, 1914]. It was also found by Leonard [1914] that if trypsin is rendered inactive by addition of acid, only a trace of its activity is restored by neutralising and then adding alkali.…”

“…The effect of heat on the digestion of fibrin and caseinogen by trypsin was next studied. It had been found previously [Edie, 1914] that trypsin when boiled in acid solution still retains much or in some cases all of its power of hydrolysing caseinogen, but in only one case was its action on fibrin tested after heating in this way. Digestion of the fibrin was still noticed, but the amount even in the case of the unheated trypsin was so small that a fresh series of experiments was undertaken.…”

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IN a previous paper [Edie, 1919] it was shown that the activity of trypsin as measured by its digestive action on fibrin and on caseinogen is affected to such a different degree by alcohol as to make it seem either that two enzymes are concerned, or, if only one enzyme, that the two substrates are acted on by different groups or side chains, one group being much more sensitive than the other. The effect of heat on the digestion of fibrin and caseinogen by trypsin was next studied.

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