PROPERTIES OF FISH HEMOGLOBINS
AUSTEN RZGGS
I. Introduction . . . . . . . . . . . .
11. Structural Properties . . . . . . . . .
A. Components and Subunits . . . . . . .
B. Primary Structure . . . . . . . . .
111. Oxygen Transport . . . . . . . . . .
A. Critique of Measurements . . . . . . .
B. Cooperativity: Heme-Heme Interaction and Oxygenation. . .
C. Effects of pH and C02 . . . . . . . .
D. Temperature Dependence
. . . . . . .
E. Adaptations of Hemoglobins in Different Fish . . .
References . . . . . . . . . . . .
Linked Changes in Aggregation of Subunits
Acknowledgments . . . . . . . . . . . .
. 209
. 210
. 210
. 217
. 222
. 223
. 227
. 229
. 232
. 235
. 246
. 246
I. INTRODUCTION
Most studies of hemoglobins have been confined to the blood and
muscle of mammals. As a result, the knowledge of the functional
and structural properties of the hemoglobins of lower vertebrates
is quite fragmentary. This preoccupation with mammalian hemoglobins is unfortunate from the standpoint of comparative physiology because the respiratory requirements of lower vertebrates vary over an
enormous range; this gives rise to many interesting adaptations. At
one extreme, the metabolic requirements for oxygen are so low that
an oxygen transport pigment is unnecessary: sufficient oxygen is physically dissolved. Thus the antarctic ice fish (Ruud, 1954) have colorless
blood and lack hemoglobin. At the other extreme, metabolically active
fish often have such large requirements for oxygen that blood transport
hemoglobin is not only necessary but even a slight anemia may be a
serious disadvantage. Fish can solve their requirements for oxygen
in many ways; the presence of a special blood hemoglobin is only one
209
AUSTEN RZGGS
I. Introduction . . . . . . . . . . . .
11. Structural Properties . . . . . . . . .
A. Components and Subunits . . . . . . .
B. Primary Structure . . . . . . . . .
111. Oxygen Transport . . . . . . . . . .
A. Critique of Measurements . . . . . . .
B. Cooperativity: Heme-Heme Interaction and Oxygenation. . .
C. Effects of pH and C02 . . . . . . . .
D. Temperature Dependence
. . . . . . .
E. Adaptations of Hemoglobins in Different Fish . . .
References . . . . . . . . . . . .
Linked Changes in Aggregation of Subunits
Acknowledgments . . . . . . . . . . . .
. 209
. 210
. 210
. 217
. 222
. 223
. 227
. 229
. 232
. 235
. 246
. 246
I. INTRODUCTION
Most studies of hemoglobins have been confined to the blood and
muscle of mammals. As a result, the knowledge of the functional
and structural properties of the hemoglobins of lower vertebrates
is quite fragmentary. This preoccupation with mammalian hemoglobins is unfortunate from the standpoint of comparative physiology because the respiratory requirements of lower vertebrates vary over an
enormous range; this gives rise to many interesting adaptations. At
one extreme, the metabolic requirements for oxygen are so low that
an oxygen transport pigment is unnecessary: sufficient oxygen is physically dissolved. Thus the antarctic ice fish (Ruud, 1954) have colorless
blood and lack hemoglobin. At the other extreme, metabolically active
fish often have such large requirements for oxygen that blood transport
hemoglobin is not only necessary but even a slight anemia may be a
serious disadvantage. Fish can solve their requirements for oxygen
in many ways; the presence of a special blood hemoglobin is only one
209