224
J. A. ALLEN AND M. R. GARRETT
chick embryo and incorporation of sulphate t o taurine in other animals
may be by another pathway. The pathway(s) does not seem t o involve
other sulphur amino acids. Thus, mercaptoethylamine may be synthesized separately or as part of the sulphate-taurinc pathway. It also
seems possible that this may be the substance that Lowe and Roberts
(1955) failed t o identify. It should be also noted that mercaptans are
present in some polychaetes, notably Travisia.
Until the work of Lowe and Roberts (1955) and Martin et al. (1966)
demonst,rated the formation of isethionic acid, taurine and sulphate ions
had generally been considered the end products of sulphur metabolism
and the forms in which sulphur is excreted. The formation of labelled
isethionic acid has been shown t o occur when sliccs of dog heart are
incubated with S35-taurinc (Read and Welty, 1962) and Peck and
Awapara (1967) show that it is formed in the brain of the rat. Isethionic
acid is the hydroxy analogue of taurine and the latter authors suggest
that it is formed from taurine in two stages by transamination to
2-oxoethane sulphonic acid followed by reduction of aldehyde. Isethionic acid has been found in invertebrates. Large quantities are
present in squid nerve fibre (almost 50y0 of the total anions) together
with taurine (Koechlin, 1955). This was, in fact, the first record of
isethionic acid in biological matcrial. Since then its presence in squid
has been confirmed and observations on its distribution have been
extended to other molluscs, Deffner and Hafter (1959, 1960) and Deffner
(1961). They also report that isethionic acid is lacking or, if present,
is in low quantities in Crustacea. They report finding cysteic acid
amide in squid nerves, which they think might have been formed from
isethionic acid and urea (Deffiier and Hafter, 1959).
Apart from the enzymatic deamination of taurine t o form isethionic
acid (and in vertebrates its conjugation with cholic acid t o form taurocholic acid) taurine appears to be the precursor of taurocyamine,
carbamyltaurine, asterubin, taurobetaine and trimethyltaurine.
Taurocyamine was first synthesized by Engel (1875) but it was not
found in a living animal until 1953 when Thoai et al. (1953a and b) and
Thoai and Robin (1954) found it in the polychaete Arenicola marina
(Linnd). They also showed that it was present in Sabellaria alveolata
(Linnd) and Clymene lumbricoides Quatrefages and in the sipunculid
Phuscolosoma elongatum Keferstcin and since then in other sedentary
polychaetes and sipunculids (Table I). It appears that while taurocyamine occurs in sedentary polychaetes, it is absent from errant species
(Table I).
Abbott and Awapara (1960) were unable to detect radio-activity in
taurocyamine following their injection experiments with Arenicola (see
J. A. ALLEN AND M. R. GARRETT
chick embryo and incorporation of sulphate t o taurine in other animals
may be by another pathway. The pathway(s) does not seem t o involve
other sulphur amino acids. Thus, mercaptoethylamine may be synthesized separately or as part of the sulphate-taurinc pathway. It also
seems possible that this may be the substance that Lowe and Roberts
(1955) failed t o identify. It should be also noted that mercaptans are
present in some polychaetes, notably Travisia.
Until the work of Lowe and Roberts (1955) and Martin et al. (1966)
demonst,rated the formation of isethionic acid, taurine and sulphate ions
had generally been considered the end products of sulphur metabolism
and the forms in which sulphur is excreted. The formation of labelled
isethionic acid has been shown t o occur when sliccs of dog heart are
incubated with S35-taurinc (Read and Welty, 1962) and Peck and
Awapara (1967) show that it is formed in the brain of the rat. Isethionic
acid is the hydroxy analogue of taurine and the latter authors suggest
that it is formed from taurine in two stages by transamination to
2-oxoethane sulphonic acid followed by reduction of aldehyde. Isethionic acid has been found in invertebrates. Large quantities are
present in squid nerve fibre (almost 50y0 of the total anions) together
with taurine (Koechlin, 1955). This was, in fact, the first record of
isethionic acid in biological matcrial. Since then its presence in squid
has been confirmed and observations on its distribution have been
extended to other molluscs, Deffner and Hafter (1959, 1960) and Deffner
(1961). They also report that isethionic acid is lacking or, if present,
is in low quantities in Crustacea. They report finding cysteic acid
amide in squid nerves, which they think might have been formed from
isethionic acid and urea (Deffiier and Hafter, 1959).
Apart from the enzymatic deamination of taurine t o form isethionic
acid (and in vertebrates its conjugation with cholic acid t o form taurocholic acid) taurine appears to be the precursor of taurocyamine,
carbamyltaurine, asterubin, taurobetaine and trimethyltaurine.
Taurocyamine was first synthesized by Engel (1875) but it was not
found in a living animal until 1953 when Thoai et al. (1953a and b) and
Thoai and Robin (1954) found it in the polychaete Arenicola marina
(Linnd). They also showed that it was present in Sabellaria alveolata
(Linnd) and Clymene lumbricoides Quatrefages and in the sipunculid
Phuscolosoma elongatum Keferstcin and since then in other sedentary
polychaetes and sipunculids (Table I). It appears that while taurocyamine occurs in sedentary polychaetes, it is absent from errant species
(Table I).
Abbott and Awapara (1960) were unable to detect radio-activity in
taurocyamine following their injection experiments with Arenicola (see