5. DISTRIBUTION OF PHOSPHOLIPIDS
233
phosphoglyceride in phospholipids been unequivocably demonstrated.
The evidence for the L-a-configuration of the glycerophosphatides has
been reviewed by Lovern (I) and by Baer et al. (2).
Two types of glycerophosphatides are widely distributed in nature.
In the one, the glycerophosphoric acid is acylated with two long-chain
fatty acids to give phosphatidic acid. The second type of glycerophosphatide, the plasmalogens, consist of an analogous series of compounds
which have one long-chain alkyl group joined to the glycerol by a
vinyl ether-type linkage and one acyl group. The relative position of
the acyl and vinyl ether group is not completely resolved. This problem
has been recently reviewed by Klenk and Debuch (3) and Dawson
(4). In the past, phospholipids having a fatty aldehyde joined to
glycerophosphoric acid by a hemiacetal- or acetal-type linkage have
been described. Since these compounds were usually isolated after
alkaline treatment of the phospholipids and the plasmalogen structure
described above is known to give a hemiacetal or acetal on alkaline
treatment, it is now generally considered that acetal phospholipids are
artifacts. A possible exception to this is the reported isolation from a
species of sea anemone of a choline plasmalogen which has no acyl
group (5).
Although glycerophosphatides with only one fatty acid have been
reported in preparations of phospholipids, e.g., by Marinetti et al. (6),
Phillips (7), and Gjone and co-workers (8), they may result from enzymatic or chemical degradation of other phospholipids during isolation.
Evidence for glycerophosphatides containing two fatty vinyl ether
groups and one based on a fatty alkyl ether of glycerophosphoric acid
has been presented by Marinetti et al. (9) and Carter and associates
(10), respectively.
The final variation in structure is in a third component which is
esterified to the glycerophosphoric acid to form a phosphate diester.
The three nitrogenous constituents choline, ethanolamine, and serine
are commonly found in the diacylglycerophosphatides whereas only
the first two occur widely in the plasmalogens. Serine plasmalogen has
been reported in brain (11). Inositol is also commonly found in the
diacylglycerophosphatides but has been reported only twice as part of
a plasmalogen (12, 13). Amino acids other than serine, peptides, and
also glycerol have been reported as the additional constituent of
glycerophosphatide by various investigators. The structure of these
and other complex glycerophosphatides, including the polyglycerophosphatides, are discussed below in relation to their occurrence in
specific tissues. The structure of the analogous choline diacylglycerophosphatide and plasmalogen and other substituents are shown in Fig. 1.
233
phosphoglyceride in phospholipids been unequivocably demonstrated.
The evidence for the L-a-configuration of the glycerophosphatides has
been reviewed by Lovern (I) and by Baer et al. (2).
Two types of glycerophosphatides are widely distributed in nature.
In the one, the glycerophosphoric acid is acylated with two long-chain
fatty acids to give phosphatidic acid. The second type of glycerophosphatide, the plasmalogens, consist of an analogous series of compounds
which have one long-chain alkyl group joined to the glycerol by a
vinyl ether-type linkage and one acyl group. The relative position of
the acyl and vinyl ether group is not completely resolved. This problem
has been recently reviewed by Klenk and Debuch (3) and Dawson
(4). In the past, phospholipids having a fatty aldehyde joined to
glycerophosphoric acid by a hemiacetal- or acetal-type linkage have
been described. Since these compounds were usually isolated after
alkaline treatment of the phospholipids and the plasmalogen structure
described above is known to give a hemiacetal or acetal on alkaline
treatment, it is now generally considered that acetal phospholipids are
artifacts. A possible exception to this is the reported isolation from a
species of sea anemone of a choline plasmalogen which has no acyl
group (5).
Although glycerophosphatides with only one fatty acid have been
reported in preparations of phospholipids, e.g., by Marinetti et al. (6),
Phillips (7), and Gjone and co-workers (8), they may result from enzymatic or chemical degradation of other phospholipids during isolation.
Evidence for glycerophosphatides containing two fatty vinyl ether
groups and one based on a fatty alkyl ether of glycerophosphoric acid
has been presented by Marinetti et al. (9) and Carter and associates
(10), respectively.
The final variation in structure is in a third component which is
esterified to the glycerophosphoric acid to form a phosphate diester.
The three nitrogenous constituents choline, ethanolamine, and serine
are commonly found in the diacylglycerophosphatides whereas only
the first two occur widely in the plasmalogens. Serine plasmalogen has
been reported in brain (11). Inositol is also commonly found in the
diacylglycerophosphatides but has been reported only twice as part of
a plasmalogen (12, 13). Amino acids other than serine, peptides, and
also glycerol have been reported as the additional constituent of
glycerophosphatide by various investigators. The structure of these
and other complex glycerophosphatides, including the polyglycerophosphatides, are discussed below in relation to their occurrence in
specific tissues. The structure of the analogous choline diacylglycerophosphatide and plasmalogen and other substituents are shown in Fig. 1.