222
AUSTEN RIGGS
The amino acid composition and some NH, and COOH terminal
amino acid determinations have been made on only a few hemoglobins
other than lamprey and carp: those of the eels, Anguilla japonica
(Yoshioka et al., 1968) and A. anguilla (Christomanos and Pavlopulu,
1967), the sea bass, Serranus gabrilla (Christomanos, 1964), salmon and
trout (Buhler, 1963; Eguchi et al., 1960), lungfish (Oldham and Riggs,
1969), and the coelacanth (Bonaventura and Riggs, 1969). Some of
these data are summarized in Table V. Unfortunately, such data are not
very illuminating concerning the primary structure, but some features are
worthy of mention. All fish examined except the lungfish have about half
as much histidine as is found in human hemoglobin. Tyrosine changes
hardly at all, and many other amino acids seem to change relatively
little. It is curious that one of the components of eel hemoglobin apparently contains six cysteinyl rcsidues while the other component has
none. Glutathione is usually present in erythrocytes. Oxidative processes
can often result in the formation of a mixed disulfide in certain hemoglobins. Steps to remove this possiblc contaminant do not appear to
have been taken in these studies of eel hemoglobin.
Although Tyr-Arg is the C-terminal sequence of the carp (Y chain
and for the human LY chain, arginine has not been reported as the C
terminus of any other fish hemoglobin; Tyr-Phe and Tyr-His are
the C-terminal sequences for the hemoglobins of both salmon and
trout; His-Leu and Leu-His
termini have been reported for eel
hemoglobin. Valine is the NH, terminus of every fish hemoglobin examined except the (Y chain of carp which is acetyl-serine, but Buhler obtained either 1 or 2 DNP valines (depending on the component) per
tetramer of salmon and trout hemoglobins; thus, some of the chains
must have NH, termini blocked to reaction with FDNB.
111. OXYGEN TRANSPORT
The in uiuo oxygen-hemoglobin equilibrium is often remarkably
sensitive to the metabolic needs of the animal. Most physiological studies
of oxygen transport in fish, either by blood, washed erythrocytes, or
hemoglobin solutions, fail to distinguish adequately between intrinsic
properties of the hemoglobin and the modifications of these propertics
which result from the intraerythrocyte environment. The detailed study of
these relationships is an important task for the futurc. Since most fish
hemolyzates contain multiple hemoglobin components which may interact with one another (see Section 111, E, l ) , it is important to know
AUSTEN RIGGS
The amino acid composition and some NH, and COOH terminal
amino acid determinations have been made on only a few hemoglobins
other than lamprey and carp: those of the eels, Anguilla japonica
(Yoshioka et al., 1968) and A. anguilla (Christomanos and Pavlopulu,
1967), the sea bass, Serranus gabrilla (Christomanos, 1964), salmon and
trout (Buhler, 1963; Eguchi et al., 1960), lungfish (Oldham and Riggs,
1969), and the coelacanth (Bonaventura and Riggs, 1969). Some of
these data are summarized in Table V. Unfortunately, such data are not
very illuminating concerning the primary structure, but some features are
worthy of mention. All fish examined except the lungfish have about half
as much histidine as is found in human hemoglobin. Tyrosine changes
hardly at all, and many other amino acids seem to change relatively
little. It is curious that one of the components of eel hemoglobin apparently contains six cysteinyl rcsidues while the other component has
none. Glutathione is usually present in erythrocytes. Oxidative processes
can often result in the formation of a mixed disulfide in certain hemoglobins. Steps to remove this possiblc contaminant do not appear to
have been taken in these studies of eel hemoglobin.
Although Tyr-Arg is the C-terminal sequence of the carp (Y chain
and for the human LY chain, arginine has not been reported as the C
terminus of any other fish hemoglobin; Tyr-Phe and Tyr-His are
the C-terminal sequences for the hemoglobins of both salmon and
trout; His-Leu and Leu-His
termini have been reported for eel
hemoglobin. Valine is the NH, terminus of every fish hemoglobin examined except the (Y chain of carp which is acetyl-serine, but Buhler obtained either 1 or 2 DNP valines (depending on the component) per
tetramer of salmon and trout hemoglobins; thus, some of the chains
must have NH, termini blocked to reaction with FDNB.
111. OXYGEN TRANSPORT
The in uiuo oxygen-hemoglobin equilibrium is often remarkably
sensitive to the metabolic needs of the animal. Most physiological studies
of oxygen transport in fish, either by blood, washed erythrocytes, or
hemoglobin solutions, fail to distinguish adequately between intrinsic
properties of the hemoglobin and the modifications of these propertics
which result from the intraerythrocyte environment. The detailed study of
these relationships is an important task for the futurc. Since most fish
hemolyzates contain multiple hemoglobin components which may interact with one another (see Section 111, E, l ) , it is important to know