Document Detail

Enzymatic rotating biosensor for cysteine and glutathione determination in a FIA system.
MedLine Citation:
PMID:  18970470     Owner:  NLM     Status:  In-Data-Review    
The high sensitivity that can be attained using an enzymatic system and mediated by catechols has been verified by on-line interfacing of a rotating biosensor and continuous flow/stopped-flow/continuous-flow processing. Horseradish peroxidase, HRP, [EC], immobilized on a rotating disk, in presence of hydrogen peroxide catalyzed the oxidation of catechols, whose back electrochemical reduction was detected on glassy carbon electrode surface at -150mV. Thus, when l-cysteine (Cys) or glutathione (GSH) was added to the solution, these thiol-containing compounds participate in Michael addition reactions with catechols to form the corresponding thioquinone derivatives, decreasing the peak current obtained proportionally to the increase of its concentration. Cys was used as the model thiol-containing compound for the study. The highest response for Cys was obtained around pH 7. This method could be used to determine Cys concentration in the range 0.05-90muM (r=0.998) and GSH concentration in the range 0.04-90muM (r=0.999). The determination of Cys and GSH were possible with a limit of detection of 0.7 and 0.3nM, respectively, in the processing of as many as 25 samples per hour. Current response of the HRP-rotating biosensor is not affected by the oxidized form of GSH and Cys (glutathione disulfide, GSSG, and l-cystine, respectively), by sulfur-containing and alkyl-amino compounds such as methionine and lysine, respectively. The interferences from easily oxidizable species such as ascorbic acid and uric acid are lowest.
Juan J J Ruiz-Díaz; Angel A J Torriero; Eloy Salinas; Eduardo J Marchevsky; María I Sanz; Julio Raba
Publication Detail:
Type:  Journal Article     Date:  2005-09-26
Journal Detail:
Title:  Talanta     Volume:  68     ISSN:  1873-3573     ISO Abbreviation:  Talanta     Publication Date:  2006 Feb 
Date Detail:
Created Date:  2008-10-30     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  2984816R     Medline TA:  Talanta     Country:  England    
Other Details:
Languages:  eng     Pagination:  1343-52     Citation Subset:  -    
Department of Chemistry, National University of San Luis, Chacabuco y Pedernera, 5700 San Luis, Argentina.
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