Short One-Pot Chemo-Enzymatic Synthesis of l-Lysine and l-Alanine Diblock Co-Oligopeptides

Abstract

Amphiphilic diblock co-oligopeptides are interesting and functional macromolecular materials for biomedical applications because of their self-assembling properties. Here, we developed a synthesis method for diblock co-oligopeptides by using chemo-enzymatic polymerization, which was a relatively short (30 min) and efficient reaction (over 40% yield). Block and random oligo(L-lysine-co-L-alanine) [oligo(Lys-co-Ala)] were synthesized using activated papain as enzymatic catalyst. The reaction time was optimized according to kinetic studies of oligo(L-alanine) and oligo(L-lysine). Using (1)H NMR spectroscopy and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, we confirmed that diblock and random co-oligopeptides were synthesized. Optical microscopy further revealed differences in the crystalline morphology between random and block co-oligopeptides. Plate-like, hexagonal, and hollow crystals were formed due to the strong impact of the monomer distribution and pH of the solution. The different crystalline structures open up interesting possibilities to form materials for both tissue engineering and controlled drug/gene delivery systems.

Chemoenzymatic Synthesis of Polypeptides for Use as Functional and Structural Materials

“…In contrast, CPDY is characterized as an exopeptidase that typically cleaves only amide bonds at C-termini. Therefore, CPDY-catalyzed polymerization avoids the hydrolysis of the polypeptide backbones of pre-existing polypeptides, resulting in efficient suppression of the broadening of the molecular weight distribution of the products that Methyl, [49,54] ethyl, [50][51][52][53][54][55][56] benzyl [54] Proteinase I, [49] papain (13)(14)(15)(16)(17)(18) [50][51][52][53][54][55][56] Glycine Methyl, [54] ethyl, [49,51,54,55] benzyl [54] Proteinase I, [49] papain (10)(11)(12)(13)(14)(15)(16)(17)(18)(19) [51,54,55] l-Leucine…”

“…[104,105] Chemoenzymatic polymerizations of l-lysine ester derivatives with and without protection of the ε-amino groups were conducted using several proteases. [47,53,61,68,69] l-Lysine methyl ester was polymerized using various proteases (most effectively, bromelain) to yield poly(l-lysine) (polyLys) with a maximum DP of 12, as shown by 1 H NMR and high-performance liquid chromatography. [47] However, the water-soluble nature of the resulting polyLys makes a tedious isolation process necessary for their application.…”

“…The copolymerization of l-lysine and l-alanine ethyl esters using papain was examined under different conditions. [53] The simultaneous addition of l-lysine and l-alanine ethyl esters to the reaction in the presence of papain resulted in the formation of the random copolymer poly(Lys-r-Ala), whereas the sequential addition of l-lysine ethyl ester and l-alanine ethyl ester to the reaction containing papain produced the block copolymer poly(Lysb-Ala). The structural differences between poly(Lys-r-Ala) and poly(Lys-b-Ala) were revealed by 1 H NMR analysis.…”

Synthesis of peptides with narrow molecular weight distributions via exopeptidase-catalyzed aminolysis of hydrophobic amino-acid alkyl esters

“…2,4,8,9 In addition to homopeptides, the syntheses of a variety of heteropeptides such as block, star and branched peptides have been reported by several researchers. 8,10,11 Peptides are often chemically synthesized by processes such as solid-phase synthesis, 12 ring-opening polymerization of N-carboxyanhydrides 13 and recombinant synthesis. 14,15 Although these methods have both drawbacks and beneficial aspects, the protease-catalyzed chemoenzymatic synthesis of peptides is an alternative to these conventional methods.…”

“…14,15 Although these methods have both drawbacks and beneficial aspects, the protease-catalyzed chemoenzymatic synthesis of peptides is an alternative to these conventional methods. 10,[16][17][18][19][20] Importantly, this method offers advantages over other processes because it requires limited or no side-chain protection of amino acids. 21 In addition, this alternative uses mild conditions and retains stereospecificity.…”