Document Detail

Photodegradation mechanism and reaction kinetics of recombinant human interferon-alpha2a.
MedLine Citation:
PMID:  17277841     Owner:  NLM     Status:  MEDLINE    
The photodegradation mechanism of recombinant human interferon-alpha2a (IFNalpha2a) has been investigated using absorption, fluorescence, and circular dichroism (CD) spectroscopies, and fluorescence photobleaching kinetics measurements under various conditions. After photobleaching, the absorption profile of aromatic amino acid residues in IFNalpha2a was almost absent, and an absorption profile showing a monotonic increase toward short wavelengths was observed. According to the CD spectrum analysis, partial unfolding of IFNalpha2a was accompanied by a complete loss of fluorescence. This unfolding was attributed to tryptophan-mediated photoinduced disulfide bond cleavage. Photooxygenation and photoionization of tryptophan (Trp) residues followed by subsequent radical reactions were the main photodegradation pathways of IFNalpha2a. Photobleaching kinetics was faster in acidic solution (pH 2.5) than in neutral solution (pH 7.4). The variation of photobleaching kinetics seemed to be caused by the structural differences in IFNalpha2a according to the solution pH. The relationship between the protein conformation and photobleaching rate could be explained based on the competition between excited state energy transfer and the photoionization process in Trp residues.
Hyong-Ha Kim; Yun Mi Lee; Jung-Keun Suh; Nam Woong Song
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2006-12-21
Journal Detail:
Title:  Photochemical & photobiological sciences : Official journal of the European Photochemistry Association and the European Society for Photobiology     Volume:  6     ISSN:  1474-905X     ISO Abbreviation:  Photochem. Photobiol. Sci.     Publication Date:  2007 Feb 
Date Detail:
Created Date:  2007-02-05     Completed Date:  2007-05-02     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  101124451     Medline TA:  Photochem Photobiol Sci     Country:  England    
Other Details:
Languages:  eng     Pagination:  171-80     Citation Subset:  IM    
Health Metrology Group, Division of Metrology for Quality Life, Korea Research Institute of Standards & Science, P.O. Box 102, Yuseong, Daejeon 305-600, Korea.
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MeSH Terms
Circular Dichroism
Disulfides / chemistry
Dithionitrobenzoic Acid / chemistry
Glutathione / chemistry
Guanidine / chemistry
Interferon Alfa-2a / chemistry*,  radiation effects*
Microscopy, Fluorescence / methods
Oxygen / chemistry
Recombinant Proteins / chemistry,  radiation effects
Sensitivity and Specificity
Spectrophotometry, Ultraviolet / methods
Time Factors
Ultraviolet Rays
Reg. No./Substance:
0/Disulfides; 0/Recombinant Proteins; 113-00-8/Guanidine; 69-78-3/Dithionitrobenzoic Acid; 70-18-8/Glutathione; 76543-88-9/Interferon Alfa-2a; 7782-44-7/Oxygen

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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