Enzymatic Catalyzed Synthesis and Triggered Gelation of Ionic Peptides

Abstract

We investigate the possibility of using the protease thermolysin to drive the synthesis and gelation of ionic-complementary peptides from nongelling precursors. In this system, short peptide fragments are continuously interconverted to form a dynamic peptide library, which eventually favors synthesis of peptides that are thermodynamically stabilized by molecular self-assembly. Thermolysin was added at a fixed concentration (0.3 mg mL(-1)) to solutions (0-300 mg mL(-1)) of the short tetrapeptide FEFK. Initially, the protease partially hydrolyzed the tetrapeptide into dipeptides in all samples. Subsequently, longer peptide sequences were found to form through reverse-hydrolysis. The stability of the different sequences was found to be dependent on their self-assembling properties. The sequences that self-assembled into antiparallel beta-sheet rich fibers became the stable products for the reverse hydrolysis reaction, while the others formed were unstable and disappeared with increasing incubation time. Ultimately, the main product of the system was octapeptide, which suggests that it represents the thermodynamically favored product of this dynamic library. Its concentration dictated the gelation behavior of the sample, and gels with moduli up to 25 kPa where obtained depending on the initial concentration of tetrapeptide.

Weak bond-based injectable and stimuli responsive hydrogels for biomedical applications

“…The oscillatory rheometry test showed that the storage modulus could go up to 25 kPa at 300 mg/mL. 88 The enzyme concentration would not change the composition of the final products, but affected the reaction kinetics and the shear moduli because of a quicker reaction and denser network formed around the enzymes if using a higher enzyme concentration. 89 This method of forming longer ionic peptides and a fibrous hydrogel from initially short, readily prepared and non-gellable peptides shows promise for peptide synthesis and potential for 3D cell culture and cell delivery for tissue engineering.…”

“…Recently, an enzymatically triggered reverse hydrolysis method was proposed to synthesize self-complementary ionic peptides and in situ formed peptide hydrogel. 88, 89 The general process is illustrated in Fig. 3B.…”

Encapsulation of curcumin in self-assembling peptide hydrogels as injectable drug delivery vehicles

“…Mixing induced, two-component physical hydrogels and enzyme catalyzed self-assembly have also been reported [24–27]. Gelation in such systems is achieved through non-covalent, physical crosslinking by secondary forces such as hydrophobic and Van der Waals interactions, as well as ionic and hydrogen bonding [28].…”

Rational Design of MMP Degradable Peptide-Based Supramolecular Filaments

“…Although this strategy works fairly well in the design of enzyme-triggered molecular assembly into well-defined nanostructures (catalytic reactions occurring on the unassembled molecules), 23−26 only limited successes have been reported on the enzyme-induced morphological transitions 27,28 and the specific degradation of self-assembled supramolecular filaments (catalytic reactions affecting the assembled nanostructures). 29−34 In the latter cases, it is not clear whether changes in the assembled structures (both morphological transition and nanostructure degradation) stems from the cleavage reactions occurring on the nanostructures, or on the individual, unassembled molecules that leads to dissociation of the assembled structures into cleavable monomers.…”