6. PROPERTIES OF FISH HEMOGLOBINS
221
region; I have therefore not attempted to indicate the G and H helical
residues in Table 111. It is of considerable interest that the only cysteinyl
residue in the molecule is complely reactive in oxy or carboxy hemoglobin
but is nonreactive in deoxyhemoglobin (Riggs, 1961). This suggests
that it may become unavailable because it is in or close to the subunit
contact region in the deoxygenated pigment. Alternatively, it might be
directed into the central cavity which probably exists in tetramic deoxygenated lamprey hemoglobin.
The hemoglobin of Lampetra fluviatilis is polymorphic. According
to Braunitzer ( 1966) this polymorphism results from partial blockage
of the NH,-terminal group: 20% of the NH, termini are free; the remainder are blocked. No other difference between the two major components appears to exist. The sequence of Lampetra fluviatilis hemoglobin shows that nine additional amino acids are present at the NH,
terminus (compared with human chains). Only two histidyl residues
are present; these are situated on opposite sides of the heme as in other
hemoglobins.
Rumen and Love (1963a,b) have isolated six hemoglobins from
the lamprey, Petromyzon marinus; the components differ substantially
in isoelectric point, ability to aggregate upon deoxygenation, amino
acid composition (Rumen, 1966), and in their oxygen equilibria (Antonini et al., 1964); some of these data are summarized in Table IV.
Recent amino acid analyses on hemoglobin V (Bonaventura, 1968)
are in substantial agreement with the earlier determination (Rumen,
1966) except that the number of cysteinyl residues determined as cysteic
acid is 1.0 rather than 3. Sequence studies by Li and Riggs (1969) show
that hemoglobin V from Petromyzon marinus differs from the hemoglobin of Lampetra fiuoiatilis in only 4 positions in peptides which constitute 110 of the 146 residues, Sequence differences in the other five
Petromyzon hemoglobins have not yet been investigated.
Table N
Some Properties of the Hemoglobins of the Lamprey, Pdromyzon murinusa
Component
1
2
3
4
5
6
8 2 0 , ~ (deoxy)
2 . 7
1 . 9
3 . 5
4 . 5
4 . 5
4 . 5
Isoelectric point
4 . 5
4 . 3
5 . 4
4 . 7
. 5 . 8
6 . 0
g/100 g
10.3
7 . 8
3 . 5
28.2
4 0 . 0
10.3
log Pso
0 . 4 0
-
0 . 8 2
0.98
0 . 8 3
0 . 8 0
n
1.10
-
1.40
1.55
1.40
1 . 3 0
0 These data were compiled from Rumen and Love (1963a,b), Rumen (1966), and
Antonini et al. (1964).
221
region; I have therefore not attempted to indicate the G and H helical
residues in Table 111. It is of considerable interest that the only cysteinyl
residue in the molecule is complely reactive in oxy or carboxy hemoglobin
but is nonreactive in deoxyhemoglobin (Riggs, 1961). This suggests
that it may become unavailable because it is in or close to the subunit
contact region in the deoxygenated pigment. Alternatively, it might be
directed into the central cavity which probably exists in tetramic deoxygenated lamprey hemoglobin.
The hemoglobin of Lampetra fluviatilis is polymorphic. According
to Braunitzer ( 1966) this polymorphism results from partial blockage
of the NH,-terminal group: 20% of the NH, termini are free; the remainder are blocked. No other difference between the two major components appears to exist. The sequence of Lampetra fluviatilis hemoglobin shows that nine additional amino acids are present at the NH,
terminus (compared with human chains). Only two histidyl residues
are present; these are situated on opposite sides of the heme as in other
hemoglobins.
Rumen and Love (1963a,b) have isolated six hemoglobins from
the lamprey, Petromyzon marinus; the components differ substantially
in isoelectric point, ability to aggregate upon deoxygenation, amino
acid composition (Rumen, 1966), and in their oxygen equilibria (Antonini et al., 1964); some of these data are summarized in Table IV.
Recent amino acid analyses on hemoglobin V (Bonaventura, 1968)
are in substantial agreement with the earlier determination (Rumen,
1966) except that the number of cysteinyl residues determined as cysteic
acid is 1.0 rather than 3. Sequence studies by Li and Riggs (1969) show
that hemoglobin V from Petromyzon marinus differs from the hemoglobin of Lampetra fiuoiatilis in only 4 positions in peptides which constitute 110 of the 146 residues, Sequence differences in the other five
Petromyzon hemoglobins have not yet been investigated.
Table N
Some Properties of the Hemoglobins of the Lamprey, Pdromyzon murinusa
Component
1
2
3
4
5
6
8 2 0 , ~ (deoxy)
2 . 7
1 . 9
3 . 5
4 . 5
4 . 5
4 . 5
Isoelectric point
4 . 5
4 . 3
5 . 4
4 . 7
. 5 . 8
6 . 0
g/100 g
10.3
7 . 8
3 . 5
28.2
4 0 . 0
10.3
log Pso
0 . 4 0
-
0 . 8 2
0.98
0 . 8 3
0 . 8 0
n
1.10
-
1.40
1.55
1.40
1 . 3 0
0 These data were compiled from Rumen and Love (1963a,b), Rumen (1966), and
Antonini et al. (1964).