The oxygen-linked zinc-binding site of human haemoglobin.

Article Details

Citation

Copy to clipboard

Gilman JG, Brewer GJ

The oxygen-linked zinc-binding site of human haemoglobin.

Biochem J. 1978 Mar 1;169(3):625-32.

PubMed ID

646791 [ View in PubMed

]

Abstract

Zn2+ is known to increase the 02 affinity of human haemoglobin. Previous data suggested that Zn2+ exerts its effect by directly binding to haemoglobin, rather than by competing with or binding to 2,3-bisphosphoglycerate. It was also shown that there are two 02-linked zinc-binding sites in haemoglobin, and that Zn2+ does not significantly alter haemoglobin co-operativity or the alkaline Bohr effect. The effect of Zn2+ on 02 affinity of haemoglobin can also be observed for other haemoglobins as diverse as those of cow and chicken. This paper presents new data on the haemoglobin-zinc interaction for normal haemoglobin, des-His146beta-haemoglobin and N-ethylsuccinimide-haemoglobin of humans. For normal haemoglobin (0.05 mM in tetramers), at 20 degrees C in buffer containing 0.1 M-Cl-, 02-dissociation-curve experiments showed that the addition of 0.4-0.5 mM-ZnS04 did not change the Bohr effect between pH 6.71 and 7.29. Similar experiments, with "zinc-ion buffers", showed that the value of the Hill coefficient, h, decreased only slightly if the concentration of free Zn2+ was held constant. For N-ethylsuccinimide-haemoglobin, Zn2+ caused less increase in O2 affinity than for normal haemoglobin. These studies, together with data on the equilibrium binding of Zn2+ to oxy-, deoxy- and des-His146beta-haemoglobins, suggest that zinc is chelated in oxyhaemoglobin by at least three amino acids, two of which are histidine-146beta and cysteine-93beta.

DrugBank Data that Cites this Article

Drug Targets

Drug	Target	Kind	Organism	Pharmacological Action	Actions
Zinc	Hemoglobin subunit beta	Protein	Humans	Unknown	Not Available	Details
Zinc acetate	Hemoglobin subunit beta	Protein	Humans	Unknown	Not Available	Details
Zinc chloride	Hemoglobin subunit alpha	Protein	Humans	Unknown	Inducer	Details
Zinc chloride	Hemoglobin subunit beta	Protein	Humans	Unknown	Inducer	Details
Zinc sulfate, unspecified form	Hemoglobin subunit alpha	Protein	Humans	Unknown	Inducer	Details
Zinc sulfate, unspecified form	Hemoglobin subunit beta	Protein	Humans	Unknown	Inducer	Details