Peptide synthesis in aqueous–organic solvent mixtures with α-chymotrypsin immobilized to tresyl chloride-activated agarose
Article first published online: 18 FEB 2004
Copyright © 1984 John Wiley & Sons, Inc.
Biotechnology and Bioengineering
Volume 26, Issue 10, pages 1146–1154, October 1984
How to Cite
Nilsson, K. and Mosbach, K. (1984), Peptide synthesis in aqueous–organic solvent mixtures with α-chymotrypsin immobilized to tresyl chloride-activated agarose. Biotechnol. Bioeng., 26: 1146–1154. doi: 10.1002/bit.260261003
- Issue published online: 18 FEB 2004
- Article first published online: 18 FEB 2004
- Manuscript Accepted: 19 JAN 1984
α–Chymotrypsin was immobilized with a high coupling yield (up to 80%) to tresyl chloride activated Sepharose CL-4B.The immobilized enzyme was tested for its ability to synthesize soluble peptides from N-acetylated amino acid esters as acyl donors and amino acid amides as acceptor amines in water–water-miscible organic solvent mixtures. It was found that the yield of peptide increased with increasing concentration of organic cosolvent. Almost complete synthesis (97%) of Ac–Phe–Ala–NH2 was obtained from Ac–Phe–OMe using a sixfold excess of Ala–NH2. The rate of peptide formation in aqueous–organic solvent mixtures was good. Thus, 0.1M peptide was formed in less than 2 h in 50 vol% DMF with 0.1 mg immobilized chymotrypsin/mL reaction mixture. The immobilized enzyme distinguished between the L and D configurations of acceptor amino acid amides even in high concentration of nonaqueous component (90% 1,4-butanediol). The effect of temperature was studied. It was found that both the yield of peptide and the stability of immobilized enzyme increased when the temperature was lowered. Experiments could be performed at subzero temperatures in the aqueous–organic solvent mixtures resulting in very high yield of peptide. After three weeks continuous operation at 4°C in 50% DMF, the immobilized enzyme retained 66%of its original synthetic activity. The activity of the immobilized enzyme was better conserved with a preparation made from agarose with a higher tresyl group content compared to a preparation made from a lower activated agarose, indicating that multiple point of attachment has a favorable effect on the stability of the enzyme in aqueous–organic solvent mixtures. The major advantage of using water-miscible instead of water-immiscible organic solvents to promote peptide syntheses appears to be the increased solubility of substrates and products, making continuous operation possible.