Document Detail

Fluorescence spectroscopy of the tryptophan microenvironment in Carcinus aestuarii hemocyanin.
MedLine Citation:
PMID:  12562099     Owner:  NLM     Status:  MEDLINE    
The steady-state and time-resolved fluorescence properties of the multitryptophan minimal subunit CaeSS2 from Carcinus aestuarii hemocyanin have been studied with the aim of probing the environment of the fluorophores within the protein matrix. Subunit a of Panulirus interruptus hemocyanin, whose X-ray structure is known, has been also studied. The results are compared with those collected with other two monomeric fractions (CaeSS1, CaeSS3) produced by dissociation of the native, oligomeric protein as well as with those of the hexameric aggregate. Three classes of tryptophan residues can be singled out by a combination of fluorescence quenching and lifetime measurements on the holo-Hc (the copper containing, oxygen binding form) and the apo-Hc (the copper-free derivative). One class of tryptophans is exposed to the protein surface. Some of these residues are proposed to be involved in the intersubunit interactions in CaeSS1 and CaeSS3 fractions whereas in CaeSS2 the protein matrix masks them. This suggests the occurrence of conformational rearrangements after detachment of the subunit from the native aggregate, which could explain the inability of CaeSS2 to reassociate. A second class of tryptophan has been correlatively assigned, by comparison with the results obtained with Panulirus interruptus hemocyanin, to residues in close proximity to the active site. The third class includes buried, active site-distant, residues.
Paolo Di Muro; Mariano Beltramini; Peter Nikolov; Irina Petkova; Benedetto Salvato; Fernanda Ricchelli
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Zeitschrift für Naturforschung. C, Journal of biosciences     Volume:  57     ISSN:  0939-5075     ISO Abbreviation:  Z. Naturforsch., C, J. Biosci.     Publication Date:    2002 Nov-Dec
Date Detail:
Created Date:  2003-02-03     Completed Date:  2003-04-14     Revised Date:  2009-11-04    
Medline Journal Info:
Nlm Unique ID:  8912155     Medline TA:  Z Naturforsch C     Country:  Germany    
Other Details:
Languages:  eng     Pagination:  1084-91     Citation Subset:  IM    
Department of Biology, University of Padova, Padova, Italy.
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MeSH Terms
Apoproteins / chemistry
Hemocyanin / chemistry*,  isolation & purification
Spectrometry, Fluorescence
Tryptophan / analysis*
Reg. No./Substance:
0/Apoproteins; 73-22-3/Tryptophan; 9013-72-3/Hemocyanin

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