title: PEGylation of cytochrome c at the level of lysine residues mediated by a microbial transglutaminase.
abstract: OBJECTIVE
  To establish a method for microbial transglutaminase (mTG)-mediated PEGylation of proteins at the level of lysine (Lys) residues.
  
  
  RESULTS
  Carboxybenzyl-glutaminyl-glycinyl-methoxypolyethylene glycol (CBZ-QG-mPEG) was prepared by introducing carboxybenzyl-glutaminyl-glycine (CBZ-QG) to mPEG amine. The analysis by Fourier transform infrared spectroscopy and SDS-PAGE showed that CBZ-QG-mPEG was successfully synthesized and can be recognized by mTG as an acyl donor to modify therapeutic protein, cytochrome c (cyt c). Finally, under an optimized condition (cyt c 0.5 mg/ml, CBZ-QG-mPEG 11.25 mg/ml, mTG 0.5 mg/ml, 37 °C, 2 h), the PEGylation yield reached 76.5 %.
  
  
  CONCLUSIONS
  This is the first study regarding the PEGylation of protein at the level of Lys residues catalyzed by mTG. The novel method could be employed to immobilize active proteins and modify therapeutic proteins.
authors.affiliation: College of Pharmaceutical Sciences, Soochow University, Suzhou, 215123, People's Republic of China.
authors.forename: Jian Qin
authors.initials: JQ
authors.lastname: Zhou
authors.affiliation: College of Pharmaceutical Sciences, Soochow University, Suzhou, 215123, People's Republic of China.
authors.forename: Ting
authors.initials: T
authors.lastname: He
authors.affiliation: College of Pharmaceutical Sciences, Soochow University, Suzhou, 215123, People's Republic of China. jwwang@suda.edu.cn.
authors.forename: Jian Wen
authors.identifier: http://orcid.org/0000-0002-1484-8649
authors.initials: JW
authors.lastname: Wang
mesh_terms: D045304:Cytochromes c / Q000378:metabolism*; D008239:Lysine / Q000378:metabolism; D015394:Molecular Structure; D011092:Polyethylene Glycols / Q000378:metabolism; D011503:Transglutaminases / Q000378:metabolism*
chemical_list: D011092:Polyethylene Glycols; D045304:Cytochromes c; D011503:Transglutaminases; D008239:Lysine
keywords: Lysine residue; Microbial transglutaminase; PEGylation; Therapeutic protein; Transglutaminase