title: [Chemical modification of chymopapain with monomethoxypolyethylene glycol and its effect on enzymic activity and antigenicity].
abstract: OBJECTIVE
  To study the effect of chemical modification of chymopapain with monomethoxypolyethylene glycol on enzymic activity and antigenicity.
  
  
  METHODS
  Under the substrate protecting and non-substrate protecting, the chymopapain (Cp) was modified with two types of mPEG derivatives mPEG1 and mPEG2. The average ratio of modified-NH2 was tested by trinitrobenzenesulfonic acid (TNBS) method, the enzymic activity was tested with macromolecular casein and ATEE as substrates, the antigenicity of modified enzyme was determined by ELISA method.
  
  
  RESULTS
  (1) Both mPEG1 and mPEG2 can reduce and eliminate antigenicity of Cp, the mPEG2 was better than mPEG1. (2) The enzymic activities of modified Cp were reduced, the enzymic activities of mPEG1-modified Cp were higher than that of mPEG2-modified Cp (especially macromolecular protein as its substrate). (3) The enzymic activities in present of ATEE were obviously higher than that in absent of substrate.
  
  
  CONCLUSIONS
  When mPEG1 as the modifier and in present of ATEE, the antigenicity of Cp was completely eliminated, and the enzymic activities were still higher.
authors.affiliation: Test Center, South China Agricultural University, Guangzhou 510642, China. happyyin@21cn.com
authors.forename: Wei
authors.initials: W
authors.lastname: Shu
authors.forename: Shi-Song
authors.initials: SS
authors.lastname: Fang
authors.forename: Tang-Bing
authors.initials: TB
authors.lastname: Cui
authors.forename: Yong
authors.initials: Y
authors.lastname: Guo
mesh_terms: D016525:Antigenic Modulation / Q000187:drug effects*; D002917:Chymopapain / Q000737:chemistry* / Q000276:immunology* / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects; D011092:Polyethylene Glycols / Q000737:chemistry* / Q000494:pharmacology
chemical_list: D011092:Polyethylene Glycols; C028210:monomethoxypolyethylene glycol; D002917:Chymopapain