The hemoglobin system of the brown moray Gymnothorax unicolor: structure/function relationships.
The Gymnothorax unicolor hemoglobin system is characterized by two components, called cathodic and anodic on the basis of their isoelectric point, which were separated by ion-exchange chromatography. The oxygen-binding properties of the purified components were studied in the absence and presence of chloride and/or GTP or ATP in the pH range 6.5-8.0. Stripped cathodic hemoglobin showed a small reverse Bohr effect, high oxygen affinity, and low co-operativity; the addition of chloride only caused a small decrease in oxygen affinity. In the presence of GTP or ATP, the oxygen affinity was dramatically reduced, the co-operativity increased, and the reverse Bohr effect abolished. Stripped anodic hemoglobin is characterized by both low oxygen affinity and co-operativity, and displayed a normal Bohr effect; the addition of chloride increased co-operativity, whereas ATP and GTP significantly modulated oxygen affinity at acidic pH values, enhancing the Bohr effect and giving rise to the Root effect. The complete amino-acid sequences of the alpha and beta chains of both hemoglobins were established; the molecular basis of the functional properties of the hemoglobins is discussed in the light of the primary structure and compared with those of other fish hemoglobins.
Tamburrini
M
M
Institute of Protein Biochemistry and Enzymology, CNR, Naples, Italy.
Verde
C
C
Olianas
A
A
Giardina
B
B
Corda
M
M
Sanna
M T
MT
Fais
A
A
Deiana
A M
AM
di Prisco
G
G
Pellegrini
M
M
D000494:Allosteric Regulation; D000595:Amino Acid Sequence; D000818:Animals; D005399:Fishes; D006454:Hemoglobins / Q000737:chemistry / Q000502:physiology*; D008969:Molecular Sequence Data; D010100:Oxygen / Q000378:metabolism; D010710:Phosphates / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
D006454:Hemoglobins; D010710:Phosphates; D010100:Oxygen