1. FATTY ACID OCCURRENCE AND DISTRIBUTION
11
not possible to define precisely the nature of the distribution. However,
the countercurrent extraction method as used by Scholfield and Hicks
(62) has given promising results, which are interpreted to support an
element of randomness in the biosynthesis of triglycerides.
More recently Mattson and Lutton (63) using pancreatic lipase,
which specifically removes the fatty acids esterified with the primary
hydroxyl groups of glycerol, have shown that the residual monoglycerides were selectively esterified.
In vegetable oils the secondary hydroxyl group is esterified mainly
with the unsaturated fatty acids, but in animal fats there is no general
pattern of distribution except that of nonrandomization of the saturated
and unsaturated fatty acids. These last results serve to emphasize the
complexity of fatty acid distribution in the glyceride and afford the possibility of finding specific differences between species when sufficiently
accurate data become available.
2. Waxes
These are usually defined as the higher fatty acid esters of the higher
fatty alcohols R · CO · O · CH 2 · R'. In practice, however, natural waxes,
as isolated, contain in addition many other components, including free
fatty acids, free fatty alcohols, ketones, hydrocarbons, sterol esters,
and sterols.
3. Phospholipids and Related Substances
These may be regarded as derivatives of α-glycerophosphoric acid
(III).
CH 2 OH
I
CHOH
OH
I
/
CH 2 · O · P=0
\H
(III)
Normally the a- and /^-positions are occupied by fatty acid radicals and
the phosphoric acid radical is united through an ester linkage to a
base such as choline, ethanolamine, or serine, or to the cyclic hexose
inositol.
a. Phosphatidylcholine (Lecithin)
(IV).
CH 2 · O > CO · R
I
CH · O · CO · R'
CH 2 · O · PO(OH) · O · CH 2 · CH 2 · N(CH 3 ) 3 OH
(IV)
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not possible to define precisely the nature of the distribution. However,
the countercurrent extraction method as used by Scholfield and Hicks
(62) has given promising results, which are interpreted to support an
element of randomness in the biosynthesis of triglycerides.
More recently Mattson and Lutton (63) using pancreatic lipase,
which specifically removes the fatty acids esterified with the primary
hydroxyl groups of glycerol, have shown that the residual monoglycerides were selectively esterified.
In vegetable oils the secondary hydroxyl group is esterified mainly
with the unsaturated fatty acids, but in animal fats there is no general
pattern of distribution except that of nonrandomization of the saturated
and unsaturated fatty acids. These last results serve to emphasize the
complexity of fatty acid distribution in the glyceride and afford the possibility of finding specific differences between species when sufficiently
accurate data become available.
2. Waxes
These are usually defined as the higher fatty acid esters of the higher
fatty alcohols R · CO · O · CH 2 · R'. In practice, however, natural waxes,
as isolated, contain in addition many other components, including free
fatty acids, free fatty alcohols, ketones, hydrocarbons, sterol esters,
and sterols.
3. Phospholipids and Related Substances
These may be regarded as derivatives of α-glycerophosphoric acid
(III).
CH 2 OH
I
CHOH
OH
I
/
CH 2 · O · P=0
\H
(III)
Normally the a- and /^-positions are occupied by fatty acid radicals and
the phosphoric acid radical is united through an ester linkage to a
base such as choline, ethanolamine, or serine, or to the cyclic hexose
inositol.
a. Phosphatidylcholine (Lecithin)
(IV).
CH 2 · O > CO · R
I
CH · O · CO · R'
CH 2 · O · PO(OH) · O · CH 2 · CH 2 · N(CH 3 ) 3 OH
(IV)