1. Peptide synthesis on Sepharose beads
W Tegge, R Frank J Pept Res. 1997 Apr;49(4):355-62. doi: 10.1111/j.1399-3011.1997.tb01137.x.
NHS-activated Pharmacia HiTrap Sepharose was modified with 1, 3-diaminopropane to give an amino-functionalized support suitable for solid-phase peptide synthesis. The amide linker p-[(R1S)-alpha-[1-(9H-fluoren-9-yl)-methoxyformamido]- 2, 4-dimethoxybenzyl]phenoxyacetic acid was incorporated and the acyl carrier protein sequence 65-74 was synthesized manually on this support by the Fmoc procedure under controlled conditions with monitoring of the coupling reactions. The performance of the support in automated multiple synthesis in open reactors, with an Abimed AMS 422 according to standard protocols, was evaluated by the synthesis of the acyl carrier protein sequence 65-74 and two other 15-mer and 18-mer peptides. The quality of the resulting crude peptides was determined by HPLC and MALDI-MS, and compared with the same sequences synthesized in parallel on the commercial peptide synthesis resin TentaGel S RAM. The modified HiTrap material was found to be particularly suited for Fmoc solid-phase peptide synthesis and should be advantageous for the utilization of immobilized peptides and peptide libraries in biological assays.
2. Resin-bound dynamic combinatorial chemistry
Brian R McNaughton, Benjamin L Miller Org Lett. 2006 Apr 27;8(9):1803-6. doi: 10.1021/ol060330+.
[reaction: see text] Dynamic combinatorial chemistry (DCC) is a promising technique for receptor-aided selection of high-affinity ligands from equilibrating combinatorial libraries. Identification of the specific ligand(s) selected is often challenging, however, due to difficulties associated with chromatographic separation and/or mass degeneracy within the library. Herein, we describe proof-of-concept experiments demonstrating a new technique termed resin-bound DCC (RB-DCC), which provides a solution to this problem.
3. Circular Aqueous Fmoc/t-Bu Solid-Phase Peptide Synthesis
Jan Pawlas, Jon H Rasmussen ChemSusChem. 2021 Aug 23;14(16):3231-3236. doi: 10.1002/cssc.202101028. Epub 2021 Jul 29.
Circular economy and aqueous synthesis are attractive concepts for sustainable chemistry. Here it is reported that the two can be combined in the universal method for peptide chemistry, fluorenylmethoxycarbonyl(Fmoc)/t-Bu solid-phase peptide synthesis (SPPS). It was demonstrated that Fmoc/t-Bu SPPS could be performed under aqueous conditions using standard Fmoc amino acids (AAs) employing TentaGel S as resin and 4 : 1 mixture of water with inexpensive green solvent PolarClean. This resin/solvent combination played a crucial dual role by virtue of improving resin swelling and solubility of starting materials. In a model coupling, TCFH and 2,4,6-collidine afforded a full conversion at only 1.3 equiv. AA, and these conditions were used in SPPS of Leu enkephaline amide affording the model peptide in 85 % yield and 86 % purity. A method to recycle the waste by filtration through a mixed ion exchange resin was developed, allowing reusing the waste without affecting quality of the peptide. The method herein obviates the use of unconventional or processed AAs in aqueous SPPS while using lower amounts of starting materials. By recycling/reusing SPPS waste the hazardous dipolar aprotic solvents used in SPPS were not only replaced with an aqueous medium, solvent use was also significantly reduced. This opens up a new direction in aqueous peptide chemistry in which efficient use of inexpensive starting materials and waste minimization is coupled with the universal Fmoc/t-Bu SPPS.
