8. POLYSACCHARIDASES
373
wheat, but the former enzyme disappears again during further ripening
(116). Careful studies by Geddes et al. (119) seem to show, however,
that there is an actual synthesis of α-amylase during the germination
period of wheat. Their results shown in Table VIII appear to confirm
the general trends noted by Kneen et al. (120).
Similar conditions of the appearance of α-amylase have been observed
during germination of other cereals. Thus «-amylase is known to occur
in the germinated forms of barley (barley malt) (21, 22, 121, 122),
wheat (120, 123), rye (124), oat (125), rice (126), maize (corn),
sorghum, and millet (127). The «-amylase from barley malt has been
obtained in the pure and crystalline state (128-130).
It was found that wheat and rye damaged by sprouting contain ten
to a hundred times more «-amylase than the undamaged grain (131).
Amylatic activity mostly «-amylase, has been described in maple and
birch saps (132, 133), and also in the tobacco leaf. The maximum activity in the latter was found in the ripest leaves; leaves with tobacco
mosaic virus have higher amylase activity than healthy ones (134).
Seeds of Canavalia ensiformis were reported to contain «-amylase.
This study was carried out on seeds from East Africa that could no
longer germinate. The enzyme was found only in the cotyledons, not in
the embryo (135).
c. Bacterial a-Amylases. The study of starch degradation by bacteria
goes back as far as 1819 (136).
A large number of bacteria are known to release starch-degrading
enzymes into the culture medium. Among more than 1000 bacterial
isolates investigated by Peltier and Beckord (137), 37 were found to
possess high dextrinizing power and, hence, to contain «-amylase, and
168 more were able to hydrolyze starch. Kneen and Beckord (138)
classified these bacterial amylases into four groups. One is called the
saccharifying type of Bacillus subtilis amylase, which is or contains ßamylase and which will be discussed together with other ß-amylases.
Another type of Kneen and Beckord's classification is the "amylase" of
B. macerans which, as was pointed out earlier, is not a hydrolase and
will not be included in the present chapter. This enzyme actually belongs to the class of transferases, although its unfortunate name always
produces confusion with hydrolytic enzymes. The transf erase nature of
B. macerans "amylase" has been convincingly demonstrated by French
et al. (139), and the name cyclodextrinase has been suggested for this
enzyme (8). The two other classes of bacterial amylases, the actual
bacterial «-amylases, are of the B. subtilis and of the B. polymyxa type.
(1). B. subtilis amylase. This enzyme is noted for its high-temperature stability (140, 141) and is known for being active even at 80° C.
373
wheat, but the former enzyme disappears again during further ripening
(116). Careful studies by Geddes et al. (119) seem to show, however,
that there is an actual synthesis of α-amylase during the germination
period of wheat. Their results shown in Table VIII appear to confirm
the general trends noted by Kneen et al. (120).
Similar conditions of the appearance of α-amylase have been observed
during germination of other cereals. Thus «-amylase is known to occur
in the germinated forms of barley (barley malt) (21, 22, 121, 122),
wheat (120, 123), rye (124), oat (125), rice (126), maize (corn),
sorghum, and millet (127). The «-amylase from barley malt has been
obtained in the pure and crystalline state (128-130).
It was found that wheat and rye damaged by sprouting contain ten
to a hundred times more «-amylase than the undamaged grain (131).
Amylatic activity mostly «-amylase, has been described in maple and
birch saps (132, 133), and also in the tobacco leaf. The maximum activity in the latter was found in the ripest leaves; leaves with tobacco
mosaic virus have higher amylase activity than healthy ones (134).
Seeds of Canavalia ensiformis were reported to contain «-amylase.
This study was carried out on seeds from East Africa that could no
longer germinate. The enzyme was found only in the cotyledons, not in
the embryo (135).
c. Bacterial a-Amylases. The study of starch degradation by bacteria
goes back as far as 1819 (136).
A large number of bacteria are known to release starch-degrading
enzymes into the culture medium. Among more than 1000 bacterial
isolates investigated by Peltier and Beckord (137), 37 were found to
possess high dextrinizing power and, hence, to contain «-amylase, and
168 more were able to hydrolyze starch. Kneen and Beckord (138)
classified these bacterial amylases into four groups. One is called the
saccharifying type of Bacillus subtilis amylase, which is or contains ßamylase and which will be discussed together with other ß-amylases.
Another type of Kneen and Beckord's classification is the "amylase" of
B. macerans which, as was pointed out earlier, is not a hydrolase and
will not be included in the present chapter. This enzyme actually belongs to the class of transferases, although its unfortunate name always
produces confusion with hydrolytic enzymes. The transf erase nature of
B. macerans "amylase" has been convincingly demonstrated by French
et al. (139), and the name cyclodextrinase has been suggested for this
enzyme (8). The two other classes of bacterial amylases, the actual
bacterial «-amylases, are of the B. subtilis and of the B. polymyxa type.
(1). B. subtilis amylase. This enzyme is noted for its high-temperature stability (140, 141) and is known for being active even at 80° C.