[Study of the structural properties of recombinant leukocyte interferon A by means of fluorescence polarization, circular dichroism, and differential microcalorimetry].
Human leukocyte interferon-A1 (IFN-alpha A) structure in solution was investigated by fluorescence polarization, circular dichroism and scanning microcalorimetry techniques. Using gel-filtration it was established that at neutral pH values and at concentration not exceeding 0.3 mg/ml IFN-alpha A has a dimeric configuration in solution. At pH below 5, IFN-alpha A exists as a monomer. Using circular dichroism technique the IFN-alpha A molecule was shown to preserve a native structure upon decreasing pH to 3.5. The rotational correlation time of IFN-alpha A molecule in dimeric and monomeric form was measured using fluorescence of DNS, conjugated with the protein, and fluorescence of tryptophan residues. Our data indicate that the shape of IFN-alpha A molecule may be approximated by the rigid ellipsoid of revolution with the axis ratio = 4:1. The intramolecular melting of IFN-alpha A was studied by scanning microcalorimetry and circular dichroism in the acidic pH range. Thermodynamic analysis reveals two independent cooperative transitions. These transitions can be explained by assuming that the IFN-alpha A molecule consists of two structural domains.
Dudich
I V
IV
Dudich
E I
EI
Kulevatskiĭ
D P
DP
Zav'ialov
V P
VP
D002152:Calorimetry, Differential Scanning; D002850:Chromatography, Gel; D002942:Circular Dichroism; D005454:Fluorescence Polarization; D006801:Humans; D006863:Hydrogen-Ion Concentration; D016898:Interferon-alpha / Q000378:metabolism*; D007962:Leukocytes / Q000378:metabolism*; D011487:Protein Conformation; D011994:Recombinant Proteins / Q000378:metabolism
D016898:Interferon-alpha; D011994:Recombinant Proteins
Issledovanie strukturnykh svoĭstv rekombinantnogo leĭkotsitarnogo interferon A metodami poliarizatsii fluorestsentsii, krugovogo dikhroizma i differentsial'noĭ mikrokalorimetryii.