Phospholipid hydroperoxide cysteine peroxidase activity of human serum albumin

Human serum albumin (HSA) reduced the phospholipid hydroperoxide, 1-palmitoyl-2-(13-hydroperoxy-cis-9,trans-11-octadecadienoyl)-l-3-phosphatidylcholine (PLPC-OOH) to the corresponding hydroxy-derivative with a high apparent affinity (Km = 9.23±0.95 µM). Removal of bound lipid during purification increased this activity. At physiological concentration, HSA reduced the phospholipid hydroperoxide in the absence of a cofactor. However, in the presence of a cofactor (reductant), the rate of the reaction was increased. All of the major aminothiols in plasma could act as reductants, the best being the most abundant, cysteine (Km = 600±80 µM). For every nanomole of PLPC-OOH reduced by HSA, 1.26 nmol of cystine was formed, indicating a reaction stoichiometry of 1 mol PLPC-OOH to 2 mol cysteine. We used chemical modification to determine which amino acid residues on HSA were responsible for the activity. Oxidation of thiol group(s) by N-ethylmaleimide led to a reduction in the rate of activity, whereas reduction of thiols by either dithiothreitol or the angiotensin-converting enzyme inhibitor, captopril, increased the activity. Both N-ethylmaleimide-modified HSA and dithiothreitol-treated HSA exhibited increased apparent affinities for PLPC-OOH. For a range of preparations of albumin with different modifications, the activity on PLPC-OOH was dependent on the amount of free thiol groups on the albumin (correlation coefficient = 0.91). Patients with lowered albumin concentrations after septic shock showed lowered total plasma thiol concentrations and decreased phospholipid hydroperoxide cysteine peroxidase (PHCPx) activities. These results therefore show for the first time that HSA exhibits PHCPx activity, and that the majority of the activity depends on the presence of reduced thiol group(s) on the albumin.

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Oxidative Alteration of Trp-214 and Lys-199 in Human Serum Albumin Increases Binding Affinity with Phenylbutazone: A Combined Experimental and Computational Investigation

International Journal of Molecular Sciences ◽

10.3390/ijms19102868 ◽

2018 ◽

Vol 19 (10) ◽

pp. 2868 ◽

Cited By ~ 1

Author(s):

Luiza Bertozo ◽

Ernesto Tavares Neto ◽

Leandro Oliveira ◽

Valdecir Ximenes

Keyword(s):

Amino Acid ◽

Human Serum Albumin ◽

Serum Albumin ◽

Human Serum ◽

Interaction Energy ◽

Score Function ◽

Oxidation Products ◽

Amino Acid Residues ◽

Computational Investigation ◽

A Current

Human serum albumin (HSA) is a target for reactive oxygen species (ROS), and alterations of its physiological functions caused by oxidation is a current issue. In this work, the amino-acid residues Trp-214 and Lys-199, which are located at site I of HSA, were experimentally and computationally oxidized, and the effect on the binding constant with phenylbutazone was measured. HSA was submitted to two mild oxidizing reagents, taurine monochloramine (Tau-NHCl) and taurine dibromamine (Tau-NBr2). The oxidation of Trp-214 provoked spectroscopic alterations in the protein which were consistent with the formation of N′-formylkynurenine. It was found that the oxidation of HSA by Tau-NBr2, but not by Tau-NHCl, provoked a significant increase in the association constant with phenylbutazone. The alterations of Trp-214 and Lys-199 were modeled and simulated by changing these residues using the putative oxidation products. Based on the Amber score function, the interaction energy was measured, and it showed that, while native HSA presented an interaction energy of −21.3 kJ/mol, HSA with Trp-214 altered to N′-formylkynurenine resulted in an energy of −28.4 kJ/mol, and HSA with Lys-199 altered to its carbonylated form resulted in an energy of −33.9 kJ/mol. In summary, these experimental and theoretical findings show that oxidative alterations of amino-acid residues at site I of HSA affect its binding efficacy.

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Effect of Physiological Concentration of Urea on the Conformation of Human Serum Albumin

The Journal of Biochemistry ◽

10.1093/jb/mvm027 ◽

2006 ◽

Vol 141 (2) ◽

pp. 261-268 ◽

Cited By ~ 16

Author(s):

N. Gull ◽

P. Sen ◽

Kabir-ud-Din ◽

R. H. Khan

Keyword(s):

Human Serum Albumin ◽

Serum Albumin ◽

Human Serum ◽

Physiological Concentration

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Calcium ion binding to clinically relevant chemical modifications of human serum albumin

Clinical Chemistry ◽

10.1093/clinchem/41.11.1654 ◽

1995 ◽

Vol 41 (11) ◽

pp. 1654-1661 ◽

Cited By ~ 16

Author(s):

H Vorum ◽

K Fisker ◽

M Otagiri ◽

A O Pedersen ◽

U Kragh-Hansen

Keyword(s):

Human Serum Albumin ◽

Serum Albumin ◽

Human Serum ◽

Conformational Changes ◽

Calcium Binding ◽

Equilibrium Dialysis ◽

Thiol Group ◽

Protein Molecule ◽

Penicillin G ◽

Lysine Residues

Abstract Calcium binding to glycated, penicilloylated, acetylated, and normal defatted human serum albumin as well as to mercapt- and nonmercaptalbumin was studied by equilibrium dialysis of radioactive Ca2+. Binding was quantified by five Scatchard constants [ni = 1, (i = 1-4) and n5 = 10]. Glycation resulted in increased k1- and k2-values and unchanged k3-k5-values, whereas penicilloylation increased all five association constants. The increments were greater the more pronounced the modification, and the enhancements caused by penicilloylation were, for the same degree of modification, greater than those produced by glycation. In contrast, acetylation by acetylsalicylate did not affect calcium binding. Likewise, binding to mercapt- and nonmercaptalbumin was the same, a finding showing that the thiol group of cysteine 34 is not important for calcium binding. D-Glucose and penicillin G are known to react with lysine residues of albumin, and the enhancement of binding resulting from glycation or penicilloylation is probably brought about by unspecific electrostatic effects, possibly supplemented by conformational changes of the protein molecule. The relative importance of the three domains of human serum albumin for calcium binding is discussed.

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Fatty acids binding to human serum albumin: Changes of reactivity and glycation level of Cysteine-34 free thiol group with methylglyoxal

Chemico-Biological Interactions ◽

10.1016/j.cbi.2014.10.008 ◽

2014 ◽

Vol 224 ◽

pp. 42-50 ◽

Cited By ~ 20

Author(s):

Ivan D. Pavićević ◽

Vesna B. Jovanović ◽

Marija M. Takić ◽

Ana Z. Penezić ◽

Jelena M. Aćimović ◽

...

Keyword(s):

Fatty Acids ◽

Human Serum Albumin ◽

Serum Albumin ◽

Human Serum ◽

Thiol Group ◽

Free Thiol ◽

Free Thiol Group

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Influence of mutations caused by radiation exposure on the bilirubin binding sites of human serum albumin

Proceedings of the National Academy of Sciences of Belarus Medical series ◽

10.29235/1814-6023-2021-18-1-46-57 ◽

2021 ◽

Vol 18 (1) ◽

pp. 46-57

Author(s):

V. V. Poboinev ◽

V. V. Khrustalev ◽

A. N. Stojarov ◽

T. A. Khrustaleva

Keyword(s):

Amino Acid ◽

Secondary Structure ◽

Human Serum Albumin ◽

Serum Albumin ◽

Radiation Exposure ◽

Human Serum ◽

Binding Sites ◽

Amino Acid Substitutions ◽

Amino Acid Residues ◽

Bilirubin Binding

In this article we analyze the bilirubin binding sites of human serum albumin from the point of view of the secondary structure instability, as well as the effect of amino acid substitutions caused by radiation exposure on the ability of albumin to bind bilirubin-IX-alpha. Based on calculations of binding energy and inhibition constants of bilirubin-albumin complexes before and after the amino acid substitutions, it was found that amino acid substitutions have different effects on the ability of human serum albumin to bind bilirubin. Amino acid substitutions Asp269-Gly269 (Nagasaki-1), Glu354-Lys354 (Hiroshima-1), Asp375-Asn375 (Nagasaki-2) reduce the binding free energy of bilirubin with human serum albumin, and the amino acid substitutions His3-Gln3 (Nagasaki-3) and Glu382-Lys382 (Hiroshima-2) increase it during molecular docking with the corresponding areas of the protein surface. The inhibition constants are significantly higher than with known binding sites. In general, mutations caused by radiation exposure cannot effect on bilirubin binding sites of human serum albumin, since the amino acid residues that are replaced do not interact with the amino acid residues from the binding sites (Leu115, Arg117, Phe134, Tyr138, Ile142, Phe149, Phe157, Tyr161, Arg186, Lys190, Lys240, Arg222). All amino acid residues from known binding sites are located in stable elements of the secondary structure of human serum albumin.The data obtained are important for understanding the impact of radiation exposure on the development of bilirubin encephalopathy in the population of the Chernobyl region and Japan.

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Phenolic acids induce changes in thiol group reactivity of defatted human serum albumin

Free Radical Biology and Medicine ◽

10.1016/j.freeradbiomed.2021.08.199 ◽

2021 ◽

Vol 177 ◽

pp. S122

Author(s):

Marija Takic ◽

Vesna Jovanović ◽

Tamara Uzelac ◽

Danijela Ristić-Medić ◽

Tamara Popović ◽

...

Keyword(s):

Human Serum Albumin ◽

Serum Albumin ◽

Human Serum ◽

Phenolic Acids ◽

Thiol Group

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Reactivity of 42 disulfides with thiol group of human haemoglobin and human serum albumin

International Journal of Biological Macromolecules ◽

10.1016/0141-8130(93)90043-l ◽

1993 ◽

Vol 15 (4) ◽

pp. 233-240 ◽

Cited By ~ 10

Author(s):

Jean-Pierre Mahieu ◽

Noëlle-Martine Gosselet ◽

Bernard Sebille ◽

Marie-Claude Garel ◽

Yves Beuzard

Keyword(s):

Human Serum Albumin ◽

Serum Albumin ◽

Human Serum ◽

Thiol Group ◽

Human Haemoglobin

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The fatty-acid-induced conformational states of human serum albumin investigated by means of multiple co-binding of protons and oleic acid

Biochemical Journal ◽

10.1042/bj2500443 ◽

1988 ◽

Vol 250 (2) ◽

pp. 443-446 ◽

Cited By ~ 11

Author(s):

J H M Dröge ◽

L H M Janssen ◽

J Wilting

Keyword(s):

Oleic Acid ◽

Fatty Acid ◽

Amino Acid ◽

Human Serum Albumin ◽

Serum Albumin ◽

Human Serum ◽

Binding Sites ◽

Conformational Transitions ◽

Amino Acid Residues ◽

Ph Stat

The binding of oleic acid to human serum albumin causes progressive changes in (a) the pK of some amino acid residues, as detected by pH-stat titration and (b) the induced molar ellipticities of albumin-bound drugs (diazepam and oxyphenbutazone), as measured by c.d. It is concluded that albumin undergoes several conformational transitions as the amount of oleic acid bound increases from 0 to about 9 molecules/molecule of protein. At least three different conformations of the protein seem to be involved. These conformations can be linked with the three classes of oleic acid-binding sites on albumin.

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