Datasets from publication: Front. Catal.Sec. BiocatalysisVolume 3 - 2023 | doi: 10.3389/fctls.2023.1275281

Introduction: Glycopeptides contain carbohydrate moieties (glycans) covalently
attached to the side chain and/or terminal peptide units. Since glycans are
present on cell surfaces, these constructs can potentially address a wide
array of therapeutic functions. To overcome the deficiencies associated
with current synthetic routes to glycopeptides, such as costly processes and
toxic reagents, this work aimed to develop versatile environmentally friendly
protease-catalyzed peptide synthetic routes to peptides decorated with a
glycan at their N-terminus.
Methods: “Grafters” were first synthesized that consist of a glycan
conjugated directly, or through a spacer, to the amine group of L-Phe-ethyl
ester (Phe-OEt). The role of Phe-OEt is to increase the conjugate’s recognition
by the protease (papain) catalytic active site. A series of grafters were
synthesized with variation of the glycan structure, linkage-chemistry, and
presence of an oligo (ethylene glycol) “spacer” of varied length between the
glycan and Phe-OEt moiety. High grafter efficiency will result by the successful
acceptance of the grafter at the enzymes S1/S2 subsites, formation of an acyl enzyme
complex and subsequent conversion to glycan-terminated oligo(Leu)x (x ≥ 1),
as opposed to construction of non-glycan N-terminated oligo(Leu)x.
Results and discussion: While glycan-Phe-OEt grafters without a spacer between the
glycan and Phe-OEt resulted in low grafter efficiency (8.3% ± 2.0%),
insertion of a short oligo(ethylene glycol) spacer between the glycan and
Phe-OEt moieties (glycan-PEGn-Phe-OEt, n ≥ 3) increased the grafter
efficiency by 3-fold–24.5% ± 1.8%. In addition, computational modeling was
performed using Rosetta software provided insights on a molecular level of
how grafter efficiency is influenced by the PEG spacer length.