Combinatorial Discovery of Peptide Dendrimer Enzyme Models Hydrolyzing Isobutyryl Fluorescein

Abstract

Two 6750-membered one-bead-one-compound peptide dendrimer combinatorial libraries L (X(4))(8)(LysX(3))(4)(LysX(2))(2)LysX(1) (X(1-4) = 14 different amino acids or deletion, Lys = branching lysine residue) and AcL (with N-terminal acetylation) were prepared by split-and-mix solid phase peptide synthesis. Screening toward fluorogenic substrates for esterase and aldolase activities using the in silica off-bead assay (N. Maillard et al., J. Comb. Chem. 2009, 11, 667-675) and bead decoding by amino acid analysis revealed histidine containing sequences active against fluorescein diacetate. Isobutyryl fluorescein, a related hydrophobic fluorogenic substrate, was preferentially hydrolyzed by dendrimers from library AcL containing hydrophobic residues such as AcH3 (AcHis)(8)(LysLeu)(4)(LysVal)(2)LysLysOH, compared to simple oligohistidine peptides as reference catalysts. Polycationic dendrimers from library L with multiple free N-termini such as H8 (His)(8)(LysβAla)(4)(LysThr)(2)LysaProNH(2) (aPro = (2S,4S)-4-aminoproline) showed stronger reactivity toward 8-acetoxypyrene-1,3,6-trisulfonate with partial acylation of N-termini. These experiments highlight the role of noncatalytic amino acids to determine substrate selectivity in peptide dendrimer esterase models.

Glycopeptide dendrimers as Pseudomonas aeruginosa biofilm inhibitors

“…This combinatorial approach was successfully employed for the identification of cobalamin ligands, 34,35 various dendritic esterases 36 and aldolase enzyme models, 37 iron binding peptide dendrimers 38 and antimicrobial peptide dendrimers. 39 Peptide dendrimers mimic natural proteins by the nature of their building blocks.…”

Peptide Dendrimers: From Enzyme Models to Antimicrobials and Transfection Reagents

“…Screening combinatorial libraries [5] uncovered further esterase dendrimers with a single catalytic histidine at the core, which was assisted by two cationic arginines for electrostatic binding to anionic pyrene trisulfonate ester substrates, however again with only partial enantioselectivity. [6,7] We further exploited the idea of an enzyme-like catalytic site at the dendrimer core to obtain a dendrimer binding to cobalamin via a cysteine residue [8] and a peroxidase dendrimer featuring a mono-coordinated Fe(ii)-bipyridine at its core. [9] Our most active catalysts, however, turned out to be typical dendrimers exploiting cooperativity between multiple catalytic residues in the dendrimer branches.…”

“…In a control experiment exposing a catalytic peptide dendrimer combinatorial library [25] to a screening protocol for discovering antimicrobial cyclic peptides, [26] we discovered polycationic peptide dendrimers with a membrane disruptive antibacterial activity. [27] Further optimization by sequence design resulted in antimicrobial peptide dendrimers (AMPDs) able to kill multidrug resistant Gram-negative bacteria such as Pseudomonas aeruginosa and Acinetobacter baumannii, which we investigated in collaboration with Dr. Thilo Köhler and Prof. Christian van Delden at the University Hospital in Geneva.…”

Expanding the Topological Space of Bioactive Peptides

“…1. To pologically diverse alkanes and their peptide analogs: an octapeptide aldolase catalyst, [8] an antimicrobial cyclodecapeptide, [9] a G3 esterase peptide dendrimer, [10] and a norbornapeptide. [11] Branching residues are marked in italics, B indicates the branching 2,3-diaminopropanoic acid (Dap).…”