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Prothrombin, albumin and immunoglobulin A form covalent complexes with alpha1-microglobulin in human plasma

Berggård, T LU ; Thelin, N ; Falkenberg, C LU ; Enghild, J J and Akerström, B LU (1997) In European Journal of Biochemistry 245(3). p.83-676
Abstract

Molecules containing the 33-kDa plasma protein alpha1-microglobulin were isolated from human plasma by anti-(alpha1-microglobulin) affinity chromatography. Five major bands could be seen after electrophoretic separation of the alpha1-microglobulin-containing proteins under native conditions. Immunoblotting demonstrated alpha1-microglobulin in all five bands. Two of these have been described previously: free alpha1-microglobulin and alpha1-microglobulin complexed with IgA (IgA x alpha1-microglobulin). The other three bands were identified as prothrombin alpha1-microglobulin, albumin x alpha1-microglobulin and dimeric alpha1-microglobulin. Prothrombin x alpha1-microglobulin were 1:2 and 1:1 complexes which carried approximately 1% of... (More)

Molecules containing the 33-kDa plasma protein alpha1-microglobulin were isolated from human plasma by anti-(alpha1-microglobulin) affinity chromatography. Five major bands could be seen after electrophoretic separation of the alpha1-microglobulin-containing proteins under native conditions. Immunoblotting demonstrated alpha1-microglobulin in all five bands. Two of these have been described previously: free alpha1-microglobulin and alpha1-microglobulin complexed with IgA (IgA x alpha1-microglobulin). The other three bands were identified as prothrombin alpha1-microglobulin, albumin x alpha1-microglobulin and dimeric alpha1-microglobulin. Prothrombin x alpha1-microglobulin were 1:2 and 1:1 complexes which carried approximately 1% of total alpha1-microglobulin, had molecular masses of about 145 kDa and 110 kDa upon SDS/PAGE and dissociated completely to free alpha1-microglobulin and prothrombin (72 kDa) when reducing agents were added, suggesting that the complexes were stabilized by disulfide bonds. The alpha1-microglobulin molecules did not inhibit cleavage of prothrombin by factor Xa and were bound to the peptides which were released upon activation of prothrombin. Albumin x alpha1-microglobulin, corresponding to 7% of total plasma alpha1-microglobulin, was a mixture between 1:1 and 1:2 complexes, with masses upon SDS/PAGE of approximately 100 kDa and 135 kDa, respectively. Both these complexes dissociated only partially to free alpha1-microglobulin and albumin when reducing agents were added. The albumin x alpha1-microglobulin complexes carried a yellow-brown chromophore similar to free alpha1-microglobulin. The complex-binding to alpha1-microglobulin did not block the fatty-acid-binding ability of albumin. The plasma concentrations of albumin x alpha1-microglobulin and prothrombin x alpha1-microglobulin were estimated to 5.2 mg/l and 1.1 mg/l, respectively.

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author
; ; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Alpha-Globulins/chemistry, Humans, Immunoglobulin A/blood, Macromolecular Substances, Protein Binding, Prothrombin/chemistry, Serum Albumin/chemistry
in
European Journal of Biochemistry
volume
245
issue
3
pages
83 - 676
publisher
Wiley-Blackwell
external identifiers
  • scopus:0030950688
  • pmid:9183005
ISSN
0014-2956
DOI
10.1111/j.1432-1033.1997.00676.x
language
English
LU publication?
yes
id
1902a267-d696-4ac2-98bd-ac48db59298f
date added to LUP
2019-05-22 10:17:32
date last changed
2021-02-21 03:20:06
@article{1902a267-d696-4ac2-98bd-ac48db59298f,
  abstract     = {<p>Molecules containing the 33-kDa plasma protein alpha1-microglobulin were isolated from human plasma by anti-(alpha1-microglobulin) affinity chromatography. Five major bands could be seen after electrophoretic separation of the alpha1-microglobulin-containing proteins under native conditions. Immunoblotting demonstrated alpha1-microglobulin in all five bands. Two of these have been described previously: free alpha1-microglobulin and alpha1-microglobulin complexed with IgA (IgA x alpha1-microglobulin). The other three bands were identified as prothrombin alpha1-microglobulin, albumin x alpha1-microglobulin and dimeric alpha1-microglobulin. Prothrombin x alpha1-microglobulin were 1:2 and 1:1 complexes which carried approximately 1% of total alpha1-microglobulin, had molecular masses of about 145 kDa and 110 kDa upon SDS/PAGE and dissociated completely to free alpha1-microglobulin and prothrombin (72 kDa) when reducing agents were added, suggesting that the complexes were stabilized by disulfide bonds. The alpha1-microglobulin molecules did not inhibit cleavage of prothrombin by factor Xa and were bound to the peptides which were released upon activation of prothrombin. Albumin x alpha1-microglobulin, corresponding to 7% of total plasma alpha1-microglobulin, was a mixture between 1:1 and 1:2 complexes, with masses upon SDS/PAGE of approximately 100 kDa and 135 kDa, respectively. Both these complexes dissociated only partially to free alpha1-microglobulin and albumin when reducing agents were added. The albumin x alpha1-microglobulin complexes carried a yellow-brown chromophore similar to free alpha1-microglobulin. The complex-binding to alpha1-microglobulin did not block the fatty-acid-binding ability of albumin. The plasma concentrations of albumin x alpha1-microglobulin and prothrombin x alpha1-microglobulin were estimated to 5.2 mg/l and 1.1 mg/l, respectively.</p>},
  author       = {Berggård, T and Thelin, N and Falkenberg, C and Enghild, J J and Akerström, B},
  issn         = {0014-2956},
  language     = {eng},
  month        = {05},
  number       = {3},
  pages        = {83--676},
  publisher    = {Wiley-Blackwell},
  series       = {European Journal of Biochemistry},
  title        = {Prothrombin, albumin and immunoglobulin A form covalent complexes with alpha1-microglobulin in human plasma},
  url          = {http://dx.doi.org/10.1111/j.1432-1033.1997.00676.x},
  doi          = {10.1111/j.1432-1033.1997.00676.x},
  volume       = {245},
  year         = {1997},
}