The Effect of Formaldehyde on the Oxygen Equilibrium of Hemoglobin

Abstract

It is now generally agreed that the S shape of the curve for the oxygenation of mammalian hemoglobin (fraction oxygenated ~s. oxygen pressure) virtually implies interaction between the four heroes attached to each hemoglobin molecule. In other words, a hemoglobin molecule will react more readily with oxygen after some of its heroes have been oxygenated (1-3). The intramolecular mechanism of this interaction is still very obscure.The problem is often attacked by consideration of the effects of changes in pH (1) or by consideration of reactions of the iron atoms of the molecule (4), although Riggs (5) has studied the effect of compounds known to react with sulfhydryl groups of the protein. Compounds that react with nitrogenous groups of the protein might also be expected to affect the combination of oxygen with hemoglobin, and the study of such reactions should provide useful information. In the present experiments, formaldehyde was chosen as a reagent because its reactions with amino acids have been explored and their equilibrium constants have been determined (6). Unfortunately, formaldehyde reacts with many functional groups of the protein moiety of hemoglobin, and the results permit no simple interpretation. However, the experiments indicate that the interaction involves nitrogen-containing groups able to combine with formaldehyde.Methods 11emogtotrin.--Concentrated ceils from freshly drawn, heparinized human blood were washed three times in isotonic saline solution, then laked for 90 to 120 minutes by the addition of an equal volume of water and 0.4 volume of toluene. After the resulting solution was centrifuged to remove debris, enough cold potassium phosphate buffer was added to make the final phosphate concentration 0.4 M. Then the solution was centrifuged again to clarify it for optical measurements before it was introduced into the tonometer. The hemoglobin was deoxygenated by successive evacuations of the tonometer, interspersed with washings with nitrogen. All steps in the preparation were carried out at 2-5°C.Measurements.--The methods of measurement have been described previously (2).

Sulfhydryl Groups and the Structure of Hemoglobin

“…2 disulfide links formed). The pH dependence of the effect of mersalyl on heine-heine interaction parallels the increasing sensitivity of --SH groups to oxidation found by Mirsky and Anson. Formaldehyde also increases the oxygen affinity and reduces heine-heine interaction (Guthe, 1954). Thus mercuric chloride, mersalyl, --SH oxidation, and formaldehyde all have very similar effects.…”

“…Actually, it is not shifted significantly. On the other hand, Guthe (1954) has shown that formaldehyde shifts the log ps0 vs. pH curve towards lower pH a very considerable amount. It therefore seems likely that formaldehyde, in contrast to mersalyl, binds an oxygen-linked acid group in addition to its binding of--SH groups.…”

“…If we bind two of these groups together with mercuric chloride forming an--S---Hg --S--linkage, heme-heme interaction is greatly reduced. Similarly, formaldehyde, also a n --S H reagent, greatly reduces heine-heine interaction (Guthe, 1954) and probably forms an --S --C H 2 ~S --linkage, in addition to forming bonds with --NH2 and imidazole groups. The same effect may be achieved under conditions believed to produce the disulfide,--S--S--linkage.…”

A severe case of methaemoglobinaemia in a Brazilian hairdresser

“…Experiments in the 1950s did, however, show a separate relationship between formaldehyde and haemoglobin. For example, in 1954, Karl F Guthe14 demonstrated that formaldehyde greatly increases the oxygen affinity of haemoglobin (more than tenfold when pH is near 7) 14. Further evidence is needed to corroborate our proposal that formaldehyde exposure may cause methaemoglobinaemia.…”

Antiseptic drugs and disinfectants with special scrutiny of COVID-19 pandemic related side effects

“…The methemoglobinemia was treated by a 1 mg/kg dose of intravenous methylene blue and the patient fully recovered within 3 days. While the aetiology in this case remains undetermined due to co-exposure with various volatile components in the products, the methemoglobinemia was most plausibly explained by the occupational formaldehyde exposure ( de Vere, Moores, Dhadwal, & Karra, 2020 ) [A], as some early experiments in the 1950s demonstrated that formaldehyde may greatly increase the oxygen affinity of haemoglobin ( Guthe, 1954 ) [E]. The case may also offer a mechanistic explanation for previous cases of fatal poisonings in connection with formaldehyde-containing hair-straightening products ( Monakhova et al, 2013 ) [E].…”