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D. J. BELL
and bacteria. Recently trehalose has been demonstrated to be the main,
if not the sole, carbohydrate of small molecular weight in insect hemolymph. So far it has not been found in higher plants (angiosperms) nor
in vertebrates. Trehalose monophosphate has long been known to occur
in yeasts.
Table II illustrates the diversity of sources from which αα-trehalose
has been obtained in recent years.
2. Sucrose and Oligosaccharides Derived from Sucrose
Sucrose (G \/\ Ff) is probably universal in the photosynthetic plants
in which it occurs in very variable amounts. It would appear that sucrose
has two parts to play in the metabolism of these organisms; the first is
to provide an easily translocated source of material from which free
energy may be obtained or which may be converted into other simple
sugars, and the second role is to provide a "starter molecule" to which
may be attached units of glucose, galactose, or fructofuranose in increasing numbers until polysaccharides are ultimately formed. It seems
possible that some of the oligosaccharides derived in this way from
sucrose may be intermediates in polysaccharide synthesis. Oligosaccharides such as raffinose (galactosyl sucrose, G \/ 6G \/\ Ff) and its
higher galactosylated homologs may act as a means of translocating
galactosyl radicals.
There is considerable evidence that the fructofuranosans of plant
origin, levans, inulins, and possibly also those of the irisin-triticin type
are built up from a sucrose starter molecule, e.g.,
Ff
Ff
Ff \/\ G
Ff
Ff
or
Ff
Ff
Ff \/\ G
Many such polysaccharides have been shown to contain a glucose moiety
(219); from some of them sucrose has actually been isolated after carefully controlled hydrolysis.
Sucrose is not commonly regarded as being a product of the animal
kingdom. However, a very few human cases of endogenous sucrosuria
have been reported (220). In these individuals, "endogenous sucrosurics," sucrose is excreted in the urine when the sugar is absent from the
diet. It may be pointed out that animals almost certainly possess the
materials out of which sucrose could be synthesized, namely D-glucosyl
uridine diphosphate and fructofuranose molecules. A sucrose phosphate
has been found as a product of photosynthesis (220a).
D. J. BELL
and bacteria. Recently trehalose has been demonstrated to be the main,
if not the sole, carbohydrate of small molecular weight in insect hemolymph. So far it has not been found in higher plants (angiosperms) nor
in vertebrates. Trehalose monophosphate has long been known to occur
in yeasts.
Table II illustrates the diversity of sources from which αα-trehalose
has been obtained in recent years.
2. Sucrose and Oligosaccharides Derived from Sucrose
Sucrose (G \/\ Ff) is probably universal in the photosynthetic plants
in which it occurs in very variable amounts. It would appear that sucrose
has two parts to play in the metabolism of these organisms; the first is
to provide an easily translocated source of material from which free
energy may be obtained or which may be converted into other simple
sugars, and the second role is to provide a "starter molecule" to which
may be attached units of glucose, galactose, or fructofuranose in increasing numbers until polysaccharides are ultimately formed. It seems
possible that some of the oligosaccharides derived in this way from
sucrose may be intermediates in polysaccharide synthesis. Oligosaccharides such as raffinose (galactosyl sucrose, G \/ 6G \/\ Ff) and its
higher galactosylated homologs may act as a means of translocating
galactosyl radicals.
There is considerable evidence that the fructofuranosans of plant
origin, levans, inulins, and possibly also those of the irisin-triticin type
are built up from a sucrose starter molecule, e.g.,
Ff
Ff
Ff \/\ G
Ff
Ff
or
Ff
Ff
Ff \/\ G
Many such polysaccharides have been shown to contain a glucose moiety
(219); from some of them sucrose has actually been isolated after carefully controlled hydrolysis.
Sucrose is not commonly regarded as being a product of the animal
kingdom. However, a very few human cases of endogenous sucrosuria
have been reported (220). In these individuals, "endogenous sucrosurics," sucrose is excreted in the urine when the sugar is absent from the
diet. It may be pointed out that animals almost certainly possess the
materials out of which sucrose could be synthesized, namely D-glucosyl
uridine diphosphate and fructofuranose molecules. A sucrose phosphate
has been found as a product of photosynthesis (220a).