Document Detail

Mass spectrometric and kinetic studies on slow progression of papain-catalyzed polymerization of L-glutamic acid diethyl ester.
MedLine Citation:
PMID:  18405672     Owner:  NLM     Status:  MEDLINE    
Papain polymerizes L-glutamic acid diethyl ester (Glu-di-OEt) regioselectively, resulting in the formation of poly (gamma-ethyl alpha-L-glutamic acid) with various degrees of polymerization of less than 13. Reaction temperatures below 20 degrees C were appropriate for the reaction in terms of suppression of non-enzymatic degradation of Glu-di-OEt and an increase in the peptide yield, while the reaction was preceded by a pronounced induction period. Mass spectrometric analyses of the reaction conducted at 0 degrees C revealed that the accumulation of the initial dimerization product, L-glutamyl-L-glutamic acid triethyl ester (Glu-Glu-tri-OEt), was limited during the induction period, and that a sequential polymer derived from a further elongation of the dimer was the tetramer, but not the trimer. Kinetic analyses of acyl transfer reactions with Glu-di-OEt and Glu-Glu-tri-OEt as acyl acceptors and Nalpha-benzoyl-L-arginine ethyl ester as an acyl donor affirmed that Glu-Glu-tri-OEt bound more strongly than Glu-di-OEt both to the S- and S'-subsites of papain. Therefore, what occurred during the initial stage of the polymerization was interpreted as follows: the rate of the papain-catalyzed dimerization of Glu-di-OEt was extremely slow, once Glu-Glu-tri-OEt was initially synthesized it exclusively bound to the active site of papain, and then papain utilized the dimer in polymerization effectively rather than the monomer.
Asako Narai-Kanayama; Hiroyuki Koshino; Keiichi Aso
Publication Detail:
Type:  Journal Article     Date:  2008-03-20
Journal Detail:
Title:  Biochimica et biophysica acta     Volume:  1780     ISSN:  0006-3002     ISO Abbreviation:  Biochim. Biophys. Acta     Publication Date:  2008 Jun 
Date Detail:
Created Date:  2008-05-16     Completed Date:  2008-07-31     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  0217513     Medline TA:  Biochim Biophys Acta     Country:  Netherlands    
Other Details:
Languages:  eng     Pagination:  881-91     Citation Subset:  IM    
Faculty of Applied Life Science, Nippon Veterinary and Life Science University, Musashino-shi, Tokyo 180-8602, Japan.
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MeSH Terms
Glutamates / chemistry*
Hot Temperature
Mass Spectrometry
Models, Chemical*
Papain / chemistry*
Polyesters / chemical synthesis*,  chemistry
Reg. No./Substance:
0/Glutamates; 0/Polyesters; 16450-41-2/glutamic acid diethyl ester; EC

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