Document Detail


Conversion of human alpha-lactalbumin to an apo-like state in the complexes with basic poly-amino acids: toward understanding of the molecular mechanism of antitumor action of HAMLET.
MedLine Citation:
PMID:  15822935     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
It was recently shown that alpha-lactalbumin associated with oleic acid (HAMLET) interacts with core histones thereby triggering apoptosis of tumor cells (J. Biol. Chem. 2003, 278, 42131). In previous work, we revealed that monomeric alpha-lactalbumin in the absence of fatty acids can also interact with histones and, moreover, with basic poly-amino acids (poly-Lys and poly-Arg) that represent simple models of histone proteins (Biochemistry 2004, 43, 5575). Association of alpha-lactalbumin with histone or poly-Lys(Arg) essentially changes its properties. In the present work, the character of the changes in structural properties and conformational stability of alpha-lactalbumin in the complex with poly-Lys(Arg) has been studied in detail by steady-state fluorescence, circular dichroism, and differential scanning calorimetry. Complex formation strongly depends on ionic strength, confirming its electrostatic nature. Experiments with the poly-amino acids of various molecular masses demonstrated a direct proportionality between the number of alpha-lactalbumin molecules bound per poly-Lys(Arg) and the surface area of the poly-amino acid random coil. The binding of the poly-amino acids to Ca2+-saturated human alpha-lactalbumin decreases its thermal stability down to the level of its free apo-form and decreases Ca2+-affinity by 4 orders of magnitude. The conformational state of alpha-lactalbumin in a complex with poly-Lys(Arg), named alpha-LActalbumin Modified by Poly-Amino acid (LAMPA), differs from all other alpha-lactalbumin states characterized to date, representing an apo-like (molten globule-like) state with substantially decreased affinity for calcium ion. The requirement for efficient conversion of alpha-lactalbumin to the LAMPA state is a poly-Lys(Arg) chain consisting of several tens of amino acid residues.
Authors:
Serge E Permyakov; Irina V Pershikova; Andrei P Zhadan; John Goers; Anush G Bakunts; Vladimir N Uversky; Lawrence J Berliner; Eugene A Permyakov
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Journal of proteome research     Volume:  4     ISSN:  1535-3893     ISO Abbreviation:  J. Proteome Res.     Publication Date:    2005 Mar-Apr
Date Detail:
Created Date:  2005-04-12     Completed Date:  2005-07-28     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  101128775     Medline TA:  J Proteome Res     Country:  United States    
Other Details:
Languages:  eng     Pagination:  564-9     Citation Subset:  IM    
Affiliation:
Institute for Biological Instrumentation of the Russian Academy of Sciences, Pushchino, Moscow Region, 142290 Russia.
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MeSH Terms
Descriptor/Qualifier:
Amino Acids / chemistry*
Antineoplastic Agents / chemistry*
Calorimetry / methods*
Circular Dichroism
Humans
Lactalbumin / chemistry*
Oleic Acid / chemistry*
Spectrometry, Fluorescence
Spectrophotometry, Ultraviolet
Grant Support
ID/Acronym/Agency:
NIH GM 56970/GM/NIGMS NIH HHS
Chemical
Reg. No./Substance:
0/Amino Acids; 0/Antineoplastic Agents; 112-80-1/Oleic Acid; 9013-90-5/Lactalbumin

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


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