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PANCREATIC EENNIN. 509
gations of Fischer and of Abderhalden and their co-workers, 1
are
much more complete and important. In this connection see page 62.
The behavior of the polypeptides with trypsin, or closely related
enzymes, is of the greatest interest and in many respects very im-
portant. Thus in the polypeptides we have a means of determining
the kind of enzyme, whether it belongs to the pepsin, trypsin, or erepsin
group. We know of no polypeptide which is split by pepsin; trypsin
splits only certain polypeptides, but not others, while the erepsin on the
contrary seems to split all polypeptides, occurring in nature, which
are composed of aminoacids. By the aid of the polypeptide reaction
Abderhalden and co-workers have also been able to show that the
trypsin-like enzyme, occurring in the blood-plasma, is not identical
with trypsin because it does not attack glycyl-Z-tyrosine, which is split
by trypsin.
Pancreatic rennin is an enzyme found in the gland and in the juice,
which coagulates neutral or alkaline milk (Kuhne and Roberts and
others). This enzyme, according to Pawlow’s school, is identical
with trypsin. The similarity of action of these two enzymes and the
fact that both are activated simultaneously from the zymogens by enter-
okinase or lime salts (Delezenne, Wohlgemuth 2
) seem to point to
this identity. On the other hand the optimum of the enzyme action
for the pancreatic rennin is 60-65° C. (Vernon), which is much higher
than for the trypsin, and Glaessner and Popper 3
have also observed
a case where the human pancreatic juice contained no rennin enzyme.
According to Halliburton and Brodie, 4
casein is converted by the pancreatic
juice of the dog into " pancreatic casein," a substance which, in regard to solubility,
stands to a certain extent between casein and paracasein (see Chapter XIII),
and which is converted into paracasein by rennin. Further investigations on
the action of this enzyme upon milk and especially upon pure casein solutions are
very desirable.
Pancreatic Calculi. The concrement from a cystic enlargement of Wirsung’s
duct in a man, as analyzed by Baldoni, contained in 1000 parts as follows:
Water 34.4, ash 126.7, protein substances 34.9, free fatty acids 133, neutral fats
124, cholesterin 70.9, soaps and pigment 499.1, parts. Scheunert and Berg-
holz 8
have reported a pancreatic calculi in the ox.
1
Fischer and Bergell, Ber. d. d. chem. Gesellsch., 36 and 37; Fischer and Abder-
halden, Sitzungsber. der Kgl. Pr. Akad. d. Wissensch., Berlin, 1905. The works of
Abderhalden and co-workers cannot be specially cited, but may be found in Zeitschr.
f. physiol. Chem., 47, 48, 49, 51, 52, 53, 54, 55, and 57.
2
Kuhne and Roberts, Maly’s Jahresber., 9; see also Edkins, Journ. of Physiol.,
12 (literature); Delezenne, Compt. rend. soc. biol., 62 and 63; Wohlgemuth, Bioch.
Zeitschr., 2.
3
Vernon, Journ. of Physiol., 12; Glaessner and Popper, Deutsch. Arch. f. klin.
Med., 94.
* Journ. of Physiol., 20.
5
Baldoni, Maly’s Jahresb., 29, 353; Scheunert and Bergholz., Zeitschr. f. physiol.
Chem., 52.
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