210
AUSTEN RIGGS
link in a series of adaptations. This fact should be borne in mind when
examining the oxygen transport properties of hemoglobins. Thus oxygen
transport depends upon the presence of gills, and/or lungs, their effective surface area, the distribution of capillaries, the rate of fluid pumping by the heart, the number of red blood cells, and the concentration
of hemoglobin within them. In addition, recognition needs to be given
to the fact that the red blood cells constitute a metabolizing tissue and
the state of this metabolism can have important consequences in modifying the oxygen transport function of the hemoglobin. For these
reasons it is necessary to consider not only the properties of the
hemoglobins in free solution but also their cellular environment and
how this environment can modify the function of the hemoglobin.
Extensive surveys of the earlier literature on hemoglobins can be
found in the reviews of Prosser and Brown (1961), Manwell ( 1960),
Antonini ( 1965), Riggs ( 1965), Braunitzer et al. ( 1964), Rossi-Fanelli
et aZ. (1964), and Wyman (1964). In addition, data on a variety of
hemoglobins are included in two studies on cyclostome and on invertebrate hemoglobins by Manwell ( 196313, 1964), which contain much
information on fish hemoglobins not suggested by their titles.
Studies of the evolution of hemoglobins are largely based on amino
acid sequence studies of mammalian blood and muscle hemoglobins
(see Ingram, 1961, 1963). Such data for lower vertebrates exist only
for one of the polypeptide chains of carp hemoglobin (Hilse and
Braunitzer, 1968) and for the hcmoglobin of the lamprey (Braunitzer
and Fujiki, 1969). No sequence data have been published on
any reptilian or amphibian hemoglobin, and fragmentary structural
data exist on only a few fish hemoglobins. Current work in several
laboratories indicates that we can look forward to substantial progress
in this area in the near future. In the meantime, the reviews by Dixon
(1966), Nolan and Margoliash (1968), and Watts (1968) may be consulted for current ideas on the process and mechanism of protein evolution. An annual atlas of protein sequence and structure (Dayhoff, 1969)
can be consulted for the current status of structural work.
11. STRUCTURAL PROPERTIES
A. Components and Subunits
1. NATURE OF MULTIPLE COMPONENTS
The hemoglobins of vertebrates are remarkably uniform in molecular
weight; most have weights near 65,000. The close similarity of the con-
AUSTEN RIGGS
link in a series of adaptations. This fact should be borne in mind when
examining the oxygen transport properties of hemoglobins. Thus oxygen
transport depends upon the presence of gills, and/or lungs, their effective surface area, the distribution of capillaries, the rate of fluid pumping by the heart, the number of red blood cells, and the concentration
of hemoglobin within them. In addition, recognition needs to be given
to the fact that the red blood cells constitute a metabolizing tissue and
the state of this metabolism can have important consequences in modifying the oxygen transport function of the hemoglobin. For these
reasons it is necessary to consider not only the properties of the
hemoglobins in free solution but also their cellular environment and
how this environment can modify the function of the hemoglobin.
Extensive surveys of the earlier literature on hemoglobins can be
found in the reviews of Prosser and Brown (1961), Manwell ( 1960),
Antonini ( 1965), Riggs ( 1965), Braunitzer et al. ( 1964), Rossi-Fanelli
et aZ. (1964), and Wyman (1964). In addition, data on a variety of
hemoglobins are included in two studies on cyclostome and on invertebrate hemoglobins by Manwell ( 196313, 1964), which contain much
information on fish hemoglobins not suggested by their titles.
Studies of the evolution of hemoglobins are largely based on amino
acid sequence studies of mammalian blood and muscle hemoglobins
(see Ingram, 1961, 1963). Such data for lower vertebrates exist only
for one of the polypeptide chains of carp hemoglobin (Hilse and
Braunitzer, 1968) and for the hcmoglobin of the lamprey (Braunitzer
and Fujiki, 1969). No sequence data have been published on
any reptilian or amphibian hemoglobin, and fragmentary structural
data exist on only a few fish hemoglobins. Current work in several
laboratories indicates that we can look forward to substantial progress
in this area in the near future. In the meantime, the reviews by Dixon
(1966), Nolan and Margoliash (1968), and Watts (1968) may be consulted for current ideas on the process and mechanism of protein evolution. An annual atlas of protein sequence and structure (Dayhoff, 1969)
can be consulted for the current status of structural work.
11. STRUCTURAL PROPERTIES
A. Components and Subunits
1. NATURE OF MULTIPLE COMPONENTS
The hemoglobins of vertebrates are remarkably uniform in molecular
weight; most have weights near 65,000. The close similarity of the con-