Covalent Inhibitors of the Gelation of Sickle Cell Hemoglobin and Their Effects on Function

Manning, James M.

doi:10.1002/9780470123102.ch2

Cited by 10 publications

(3 citation statements)

References 138 publications

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“…As found in a previous study, the NH 2 group of the Val-1(β), Lys-82(β) and Lys-144(β) of human Hb attacks the carbon of the ester bond (-COO-) of the methyl acetyl phosphate to yield acetylated Hb 26 . This is a type of chemical modification of Hb and such covalent chemical modification inhibits the sickling of red blood cells 27 . In another study, enzyme-like activities of Hb were found.…”

Section: Discussionmentioning

confidence: 99%

Hemoglobin catalyzes CoA degradation and thiol addition to flavonoids

Nagakubo

Kumano

Hashimoto

et al. 2018

Sci Rep

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In the presence of CoA, cell-free extracts prepared from porcine liver was found to convert 7,8-dihydroxyflavone (DHF) to a pantetheine conjugate, which was a novel flavonoid. We purified a 7,8-DHF-converting enzyme from the extracts, and identified it as hemoglobin (Hb). The purified Hb showed the following two activities: (i) degradation of CoA into pantetheine through hydrolytic cleavage to yield pantetheine and 3′-phospho-adenosine-5′-diphosphate (ADP) independently of heme, and (ii) addition of a thiol (e.g., pantetheine, glutathione and cysteine) to 7,8-DHF through C-S bond formation. Human Hb also exhibited the above flavonoid-converting activity. In addition, heme-containing enzymes such as peroxidase and catalase added each of pantetheine, glutathione and cysteine to the flavonoid, although no pantetheine conjugates were synthesized when CoA was used as a substrate. These findings indicated that the thiol-conjugating activity is widely observed in heme-containing proteins. On the other hand, only Hb catalyzed the hydrolysis of CoA, followed by the thiol conjugation to synthesize the pantetheine conjugate. To the best of our knowledge, this is the first report showing that Hb has the catalytic ability to convert naturally occurring bioactive compounds, such as dietary flavonoids, to the corresponding conjugates in the presence of thiol donors or CoA.

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Section: Discussionmentioning

confidence: 99%

Hemoglobin catalyzes CoA degradation and thiol addition to flavonoids

Nagakubo

Kumano

Hashimoto

et al. 2018

Sci Rep

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“…18 These protein molecules precipitate under low concentrations of oxygen. When this occurs, the molecules bind together in long rods and stretch normally flexible red blood cells into rigid sickle shapes like Herrick saw in the sickle cell anemia patients' blood smear.…”

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“…When this occurs, the molecules bind together in long rods and stretch normally flexible red blood cells into rigid sickle shapes like Herrick saw in the sickle cell anemia patients' blood smear. 18 Similarly, a substitution at position 102 of the Prion Protein (PrP) of the amino acid proline by leucine turns PrP into an infectious "scrapie" form -a prion (putative cause of mad cow disease). In its benign non-pathogenic state, PrP twists into multiple a-helices.…”

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confidence: 99%

Compared to Synthetic Polymers, Proteins Are Awesome

Chen

2004

J Chinese Chemical Soc

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This paper is written for undergraduate chemistry students who are introduced to the elegant biosynthesis and folding of proteins as compared to synthetic polymers. The uniqueness of proteins among other synthetic and biopolymers is discussed. Proteins are characterized by unique 3-dimensional structures that are dictated by their 1-dimensional amino acid sequences. The driving force of the 3-d conformation lies in the tendency of hydrophobic residues to stay away from an aqueous environment. As a result of such hydrophobic forces, proteins are very compact. Conformational folding is much faster than the time needed for an exhaustive search of the global minimum energy. Additionally, conformational changes induced by environmental factors such as pH, temperature, or ligands are cooperative. Such cooperative folding is given by an example of hemoglobin binding to oxygen molecules. Polymer synthesis designed to mimic protein structures has given useful polymers with many practical applications.

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Properties of a recombinant human hemoglobin double mutant: Sickle hemoglobin with Leu‐88 (β) at the primary aggregation site substituted by Ala

Llano¹,

Manning²

1994

Protein Science

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A recombinant double mutant of hemoglobin (Hb), E6V/L88A(@), was constructed to study the strength of the primary hydrophobic interaction in the gelation of sickle Hb, Le., that between the mutant Val-6(0) of one tetramer and the hydrophobic region between Phe-85(/3) and Leu-88(/3) on an adjacent tetramer. Thus, a construct encoding the donor Val-6(@ of the expressed recombinant HbS and a second mutation encoding an Ala in place of Leu-88(@) was assembled. The doubly mutated 0-globin gene was expressed in yeast together with the normal human a-chain, which is on the same plasmid, to produce a soluble Hb tetramer. Characterizations of the Hb double mutant by mass spectrometry, by HPLC, and by peptide mapping of tryptic digests of the mutant P-chain were consistent with the desired mutations. The absorption spectra in the visible and the ultraviolet regions were practically superimposable for the recombinant Hb and the natural Hb purified from human red cells. Circular dichroism studies on the overall structure of the recombinant Hb double mutant and the recombinant single mutant, HbS, showed that both were correctly folded. Functional studies on the recombinant double mutant indicated that it was fully cooperative. However, its gelation concentration was significantly higher than that of either recombinant or natural sickle Hb, indicating that the strength of the interaction in this important donor-acceptor region in sickle Hb was considerably reduced even with such a conservative hydrophobic mutation.

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Covalent Inhibitors of the Gelation of Sickle Cell Hemoglobin and Their Effects on Function

Cited by 10 publications

References 138 publications

Hemoglobin catalyzes CoA degradation and thiol addition to flavonoids

Hemoglobin catalyzes CoA degradation and thiol addition to flavonoids

Compared to Synthetic Polymers, Proteins Are Awesome

Properties of a recombinant human hemoglobin double mutant: Sickle hemoglobin with Leu‐88 (β) at the primary aggregation site substituted by Ala

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