Enzymatic Modification of Soluble Cyanophycin Using the Type II Peptidyl Arginine Deiminase from Oryctolagus cuniculus

• Published in: Macromolecular bioscience 2016-07, Vol.16 (7), p.1064-1071
• Main Authors: Wiefel, Lars, Steinbüchel, Alexander
• Format: Article
• Language: English
• Subjects: Animals; Arginine - chemistry; Bacterial Proteins - chemical synthesis; Bacterial Proteins - chemistry; cyanophycin; dipeptides; Dipeptides - chemistry; Dipeptides - metabolism; enzymatic modification; Escherichia coli; Escherichia coli - genetics; Gene Expression Regulation, Enzymologic; Hydrolases - biosynthesis; Hydrolases - chemistry; Hydrolases - genetics; Oryctolagus cuniculus; peptidyl arginine deiminase; Protein-Arginine Deiminases; Rabbits
• ISSN: 1616-5187; 1616-5195
• DOI: 10.1002/mabi.201500433

An increased structural variety expands the number of putative applications for cyanophycin (multi‐l‐arginyl‐poly‐[l‐aspartic acid], CGP). Therefore, structural modifications of CGP are of major interest; these are commonly obtained by modification and optimization of the bacterial producing strain or by chemical modification. In this study, an enzymatic modification of arginine side chains from lysine‐rich CGP is demonstrated using the peptidyl arginine deiminase from Oryctolagus cuniculus, purified from Escherichia coli after heterologous expression. About 10% of the arginine side chains are converted to citrulline which corresponds to 4% of the polymer's total side chains. An inhibition of the reaction in the presence of small amounts of l‐citrulline is observed, thereby explaining the low conversion rate. CGP dipeptides can be modified with about 7.5 mol% of the Asp‐Arg dipeptides being converted to Asp‐Cit. These results show that the enzymatic modification of CGP is feasible, opening up a whole new area of possible CGP modifications for further research. The purified type II peptidyl arginine deiminase of Oryctolagus cuniculus is used for the first enzymatic modification of arginine residues of the biopolymer cyanophycin and its dipeptides. About 4 mol% of the polymer side chains and 7.5 mol% of the dipeptides can be converted to citrulline. An inhibitory effect for free citrulline can be identified.