Human Serum Albumin: Crystal Structure

1UOR

Structure determined by He and Carter (1), Protein Data Bank entry 1UOR.
To view the structure of the asymmetric unit using interactive 3D software,
click on this link to the Protein Data Bank: 1UOR




1AO6

Structure determined by Sugio et al. (2), Protein Data Bank entry 1AO6.
To view the structure of the asymmetric unit using interactive 3D software,
click on this link to the Protein Data Bank: 1AO6




LYS - 525, TYR - 401

Detailed view demonstrating the close proximity of the Lysine - 525 side chain (shown in yellow) to the aromatic ring of Tyrosine - 401 (shown in orange). From the structure determined by He and Carter (1), Protein Data Bank entry 1UOR. Deprontonated epsilon-amino groups of lysine side chains are known to quench the fluorescence signal originating from nearby tyrosine residues. Therefore, deprotonated lysine residues in close proximity to tyrosines are candidate quenching groups. Data from tyrosine fluorescence emission studies (3) in combination with the crystal structure provide experimental evidence suggesting the existence of lysine residues in albumin with unusually low pK's.




LYS - 525, TYR - 401

Detailed view demonstrating the close proximity of the Lysine - 525 side chain (shown in yellow) to the aromatic ring of Tyrosine - 401 (shown in orange). From the structure determined by Sugio et al. (2), Protein Data Bank entry 1A06. The distance between the nitrogen atom of the Lysine - 525 side chain and the oxygen atom of the Tyrosine - 401 side chain is 4.2 Angstroms. Deprontonated epsilon-amino groups of lysine side chains are known to quench the fluorescence signal originating from nearby tyrosine residues. Therefore, deprotonated lysine residues in close proximity to tyrosines are candidate quenching groups. Data from tyrosine fluorescence emission studies (3) in combination with the crystal structure provide experimental evidence suggesting the existence of lysine residues in albumin with unusually low pK's.




References:

1. He XM, Carter DC. Atomic structure and chemistry of human serum albumin. Nature. 1992; 358: 209-215. [ Abstract on PubMed ].

2. Sugio S, Kashima A, Mochizuki S, Noda M, Kobayashi K. Crystal Structure of Human Serum Albumin at 2.5 Angstrom Resolution. Protein Eng. 1999; 12: 439-446. [ Full text is available online at http://peds.oupjournals.org/cgi/content/full/12/6/439 ].

3. Dockal M, Carter DC, Ruker F. Conformational transitions of the three recombinant domains of human serum albumin depending on pH. J Biol Chem. 2000; 275: 3042-3050. [ Full text is available online at http://www.jbc.org/cgi/content/full/275/5/3042 ].

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