Influence of ligation state and concentration of hemoglobin A on its cross-linking by glycolaldehyde: functional properties of cross-linked, carboxymethylated hemoglobin.
The ligation state of hemoglobin during its cross-linking by glycolaldehyde influences the ultimate oxygen affinity of the cross-linked protein. Thus, if the cross-linking is performed with carbonmonoxy-hemoglobin, the oxygen affinity increases slightly to a P50 of 7 mmHg from a P50 of 9 mmHg for unmodified hemoglobin. In contrast, when deoxyhemoglobin is cross-linked with glycolaldehyde, the oxygen affinity of the product decreases (P50 = 15 mmHg). When deoxyhemoglobin is first carboxymethylated and then cross-linked with glycolaldehyde, an even lower oxygen affinity is achieved (P50 = 23 mmHg). Carboxymethylated hemoglobin is very responsive to the presence of 5% CO2 with a P50 of 33 mmHg, which is lowered further to 42 mmHg when chloride (0.1 M) is also present. Hemoglobin carboxymethylated and cross-linked under anaerobic conditions is also responsive to the modulators CO2 and chloride with a resultant oxygen affinity of 27 mmHg. The type of cross-linking of liganded hemoglobin by the mild reagent glycolaldehyde is dependent upon the initial hemoglobin concentration. Thus, with dilute hemoglobin (45 microM in tetramer), cross-linking by glycolaldehyde (50 mM) results in about 75% of 64,000 molecular weight species (some of which are cross-linked within tetramer) and 25% of intertetrameric cross-linked species with a range of molecular weights averaging 128,000-512,000. With hemoglobin solutions of higher concentration (360 microM), the amount of the higher molecular weight species increases to about 65% with a corresponding reduction to 35% in the 64,000 molecular weight component.
Manning
L R
LR
Rockefeller University, New York, New York 10021.
Manning
J M
JM
D000079:Acetaldehyde / Q000031:analogs & derivatives* / Q000494:pharmacology; D002263:Carboxyhemoglobin / Q000378:metabolism*; D002712:Chlorides / Q000494:pharmacology; D003432:Cross-Linking Reagents / Q000494:pharmacology*; D006441:Hemoglobin A / Q000187:drug effects / Q000378:metabolism*; D006801:Humans; D007700:Kinetics; D008024:Ligands; D010108:Oxyhemoglobins / Q000378:metabolism
D002712:Chlorides; D003432:Cross-Linking Reagents; D008024:Ligands; D010108:Oxyhemoglobins; D006441:Hemoglobin A; D002263:Carboxyhemoglobin; C029774:oxyhemoglobin A; D000079:Acetaldehyde; C010972:glycolaldehyde