366
PETER BERNFELD
histological examinations of glands from mice of each strain ruled out
genetic differences in amount of connective tissue or number of ducts
and acini (59).
Unlike pancreatic amylase, salivary amylase is present in the newborn and has even been found in the parotic gland of bovine embryos
(61).
Salivary amylase in man originates mostly from the parotic gland
(62), and both submaxillary and sublingual glands also contribute to
the amylase secretion. Man produces about 1 liter of saliva from all
three glands during 24 hours, containing approximately 0.4 gm. of pure
amylase (63), together with about 3gm. of other proteic material, in
particular mucoids and mucoproteins, a few other enzymes such as
certain proteases, an oxidase, lysozyme (64), and possibly hyaluronidase (65), and in addition, a number of inorganic salts, notably sodium
chloride and potassium, calcium and magnesium phosphates, sulfate,
bicarbonate, and thiocyanate. Human salivary amylase has been obtained in pure and crystalline form (63, 66).
(2). Pancreatic amylase. The richest source of animal α-amylases is
no doubt the pancreas. In contrast to other pancreatic enzymes, in particular proteases, amylase does not occur in form of a zymogen in the
pancreatic secretion but has always been observed therein as the active
enzyme.
Pancreatic amylase has been found in the order of decreasing activity in swine, dog, beef, and sheep (67), in man, the horse, and further in the rat, mouse, chicken, dog, and guinea pig (44) (see also
Table IV). The pancreatic enzyme has been reported to occur early in
bovine embryos (61), as does salivary amylase, whereas other workers
claimed that the pancreatic secretions of the newborn do not contain
amylase, which arrives therein only after several months (43).
It should be noted that although amylase generally occurs in the
pancreas of those animal species where it also exists in the saliva, it is
found in addition in animals where no salivary amylase can be detected, i.e., in the dog, horse, beef, etc.
The synthesis and secretion of amylase by pigeon pancreatic slices
has been studied in vitro by Hokin (68). An interesting relationship
between pancreatic amylase and thyroid function was described by
Townsend et al. (69), who found that thyroidectomy, with or without
I
131 , reduces both the pancreatic weight and the amylolytic activity.
Pancreatic amylase from various species has been obtained in pure
and crystalline form; i.e., from swine (70-72), man (73, 74), and rat
(75). Although the proteic nature of pancreatic amylase has been well
established (71, 76, 77) and the amino acid composition of crystalline
PETER BERNFELD
histological examinations of glands from mice of each strain ruled out
genetic differences in amount of connective tissue or number of ducts
and acini (59).
Unlike pancreatic amylase, salivary amylase is present in the newborn and has even been found in the parotic gland of bovine embryos
(61).
Salivary amylase in man originates mostly from the parotic gland
(62), and both submaxillary and sublingual glands also contribute to
the amylase secretion. Man produces about 1 liter of saliva from all
three glands during 24 hours, containing approximately 0.4 gm. of pure
amylase (63), together with about 3gm. of other proteic material, in
particular mucoids and mucoproteins, a few other enzymes such as
certain proteases, an oxidase, lysozyme (64), and possibly hyaluronidase (65), and in addition, a number of inorganic salts, notably sodium
chloride and potassium, calcium and magnesium phosphates, sulfate,
bicarbonate, and thiocyanate. Human salivary amylase has been obtained in pure and crystalline form (63, 66).
(2). Pancreatic amylase. The richest source of animal α-amylases is
no doubt the pancreas. In contrast to other pancreatic enzymes, in particular proteases, amylase does not occur in form of a zymogen in the
pancreatic secretion but has always been observed therein as the active
enzyme.
Pancreatic amylase has been found in the order of decreasing activity in swine, dog, beef, and sheep (67), in man, the horse, and further in the rat, mouse, chicken, dog, and guinea pig (44) (see also
Table IV). The pancreatic enzyme has been reported to occur early in
bovine embryos (61), as does salivary amylase, whereas other workers
claimed that the pancreatic secretions of the newborn do not contain
amylase, which arrives therein only after several months (43).
It should be noted that although amylase generally occurs in the
pancreas of those animal species where it also exists in the saliva, it is
found in addition in animals where no salivary amylase can be detected, i.e., in the dog, horse, beef, etc.
The synthesis and secretion of amylase by pigeon pancreatic slices
has been studied in vitro by Hokin (68). An interesting relationship
between pancreatic amylase and thyroid function was described by
Townsend et al. (69), who found that thyroidectomy, with or without
I
131 , reduces both the pancreatic weight and the amylolytic activity.
Pancreatic amylase from various species has been obtained in pure
and crystalline form; i.e., from swine (70-72), man (73, 74), and rat
(75). Although the proteic nature of pancreatic amylase has been well
established (71, 76, 77) and the amino acid composition of crystalline