220
AUSTEN FUGGS
man, horse, and carp responsible for these contacts are compared in
Table 11, together with the corresponding data on lamprey hemoglobin.
Evidently the a part of the a& points of contact have changed very
little between carp and man: eight of the ten residues are identical; in
contrast, only four residues are invariant in the regions in lamprey hemoglobin homologous with the contacts in the human a chain. Of the sixteen a-chain residues of the (Y part of the alp1 contact, only seven have
remained unchanged between carp and man (Table 111).
The dissociation of lamprey hemoglobin from tetramer to monomer
upon oxygenation (see Section 111, E, 1) may result in part from differences in the nature or position of the residues responsible for the alpz
and alp1 contacts in higher organisms. Other residues close to these
contacts may exert a large influence as in human hemoglobin Kansas
(Bonaventura and Riggs, 1968) which has a neutral substitution in the
G helix close to the alp2 contact. This substitution causes a remarkable
oxygenation-induced dissociation from tetramer to dimer. The lamprey
sequence appears to have only limited homology in the alp1 contact
Table I11
The Homologous Residues of the cvlj3, Contact Region from the
~1 Chains of Horse, Man, and Carp, Compared with the
Corresponding Positions in Lamprey Hemoglobin4
Position
Residues
Reeidrie No.
Helix
Horse
Human
Carp
Lamprey
30
31
34
35
36
103
104
106
107
111
114
117
119
122
123
126
B11
Glu
B12
Arg
B15
Leu
B16
GlY
c1
Phe
GI0
His
G11
CYS
G13
Leu
G14
Ser
GI8
Val
GH2
Pro
GH5
Phe
H2
Pro
H5
His
H6
Ala
H9
ASP
Glu
Arg
Leu
Ser
Phe
His
CYS
Leu
Val
Ala
Pro
Phe
Pro
His
Ala
ASP
GlY
Val
Arg
LYS
Thr
Thr
Val
Ser
TYr
Thr
Asn
His
Val
Val
Phe
Pro
Phe
Pro
His
Met
ASP
These contact positions for the hemoglobins of horse and man are those determined
by Peruta et al. (1968). The corresponding positions for carp and lamprey have been
determined by homology where possitle.
AUSTEN FUGGS
man, horse, and carp responsible for these contacts are compared in
Table 11, together with the corresponding data on lamprey hemoglobin.
Evidently the a part of the a& points of contact have changed very
little between carp and man: eight of the ten residues are identical; in
contrast, only four residues are invariant in the regions in lamprey hemoglobin homologous with the contacts in the human a chain. Of the sixteen a-chain residues of the (Y part of the alp1 contact, only seven have
remained unchanged between carp and man (Table 111).
The dissociation of lamprey hemoglobin from tetramer to monomer
upon oxygenation (see Section 111, E, 1) may result in part from differences in the nature or position of the residues responsible for the alpz
and alp1 contacts in higher organisms. Other residues close to these
contacts may exert a large influence as in human hemoglobin Kansas
(Bonaventura and Riggs, 1968) which has a neutral substitution in the
G helix close to the alp2 contact. This substitution causes a remarkable
oxygenation-induced dissociation from tetramer to dimer. The lamprey
sequence appears to have only limited homology in the alp1 contact
Table I11
The Homologous Residues of the cvlj3, Contact Region from the
~1 Chains of Horse, Man, and Carp, Compared with the
Corresponding Positions in Lamprey Hemoglobin4
Position
Residues
Reeidrie No.
Helix
Horse
Human
Carp
Lamprey
30
31
34
35
36
103
104
106
107
111
114
117
119
122
123
126
B11
Glu
B12
Arg
B15
Leu
B16
GlY
c1
Phe
GI0
His
G11
CYS
G13
Leu
G14
Ser
GI8
Val
GH2
Pro
GH5
Phe
H2
Pro
H5
His
H6
Ala
H9
ASP
Glu
Arg
Leu
Ser
Phe
His
CYS
Leu
Val
Ala
Pro
Phe
Pro
His
Ala
ASP
GlY
Val
Arg
LYS
Thr
Thr
Val
Ser
TYr
Thr
Asn
His
Val
Val
Phe
Pro
Phe
Pro
His
Met
ASP
These contact positions for the hemoglobins of horse and man are those determined
by Peruta et al. (1968). The corresponding positions for carp and lamprey have been
determined by homology where possitle.