The influence of the side‐chain sequence on the structure–activity correlations of immunomodulatory branched polypeptides. Synthesis and conformational analysis of new model polypeptides

Abstract

New branched polypeptides were synthesized for a detailed study of the influence of the side-chain structure on the conformation and biological properties. The first subset of polypeptides were prepared by coupling of tetrapeptides to poly[L-Lys]. These polymers contain either DL-Ala3-X [poly[Lys-(X-DL-Ala3)n]] or X-DL-Ala3 [poly[Lys-(DL-Ala3-X)n] (n less than or equal to 1)] tetrapeptide side chains. Another group of branched polymers comprise a mixture of DL-Alam and of DL-Alam-X oligomeric branches in a random distribution [poly[Lys-(DL-Alam-Xi)] (i less than 1, m approximately 3)]. In each subset the X = Leu or Phe derivatives were prepared. The N-protected tetrapeptides were synthesized by conventional liquid phase methods and were coupled as active esters. The degree of racemization was found relatively high both for active esters and coupled derivatives, when optically active amino acids were in the C-terminal position of the tetrapeptides. In the case of the poly[Lys-(Leu-DL-Ala3)n] derivative, comparative experiments were carried out using various methodical alterations. The highest stereochemical homogeniety could be achieved when the tetrapeptide active ester was synthesized by the "backing off" method. CD spectra of poly[Lys-(Xi-DL-Alam)] (i less than 1, m approximately 3) and of poly[Lys-(X-DL-Ala3)n] were analyzed and compared to those of poly[Lys-(DL-Alam-Xi)] and of poly[Lys-(DL-Ala3-X)n]. All measurements were performed in water solutions of varying pH values and ionic strengths. The data obtained suggest that branched polypeptides containing a mixture of two different types of oligomeric side chains (DL-Alam and DL-Alam-Xi or Xi-DL-Alam) distributed randomly adopt an almost identical conformation to those that comprise only the respective tetrapeptide (DL-Ala3-X or X-DL-Ala3) branches. The results also indicate that the tendency to form an ordered structure is determined by the identity and the position of the chiral amino acid X (Phe or Leu) in the side chain.

The Influence of Branched Polypeptide Carriers on the Immunogenicity of Predicted Epitopes of HSV‐1 Glycoprotein D

“…Preparation of HSV-1 gD carrier-peptide conjugates. Production and characterization of synthetic HSV-1 gD peptides and the synthetic polypeptide carriers are described elsewhere in more detail [9,19,22]. Three overlapping peptides (^"PEDSALLEDPVG'"''-NH;, -'^PEDSALLED-^'-COOH and ™SALLEDPVG-'"'-NH;) of the 273-284 region or the N-terminal HSV-1 gD sequence ('KYALADASLKMADPNRFRGKDLP-') were conjugated to the branched polypeptides poly[L-Lys-(DL-Alav4)] (AK) or poly[L-Lys-(Leufl76-DL-Ala3 95)] (LAK) and to KLH via their free carboxyl groups using a water soluble N-cyclohexyl-N, (2-morpholinoethyOcarbodiimide methyl p-toluene sulfonate (CMC), or N-ethyl-N- [3-(dimethylamino)propylcarbodiimide hydrochloride (EDC) as coupling reagents in phosphate buffer at pH6.0.…”

Hogyan befolyásolja a primer szerkezet elágazó láncú polipeptidek térszerkezetét és konjugátumaik funkcionális tulajdonságait?

“…Az X és U aminosav megválasztásával létre lehetett hozni különbözõ töltésû, töltéssûrûségû, hidrofil/ hidrofób karakterû vegyületeket. [3][4][5][6][7][8][9][10][11][12][13][14][15][16] Az MTA Kémiai Tudományok osztálya Oláh György emlékülésén (Budapest, 2017. május 3.) elhangzott elõadás alapján készült jelen össze-foglaló áttekintést nyújt e vegyületek szintézisé-nek stratégiájáról, fõbb lépéseirõl és három különbözõ elágazó láncú vegyületcsoport tanulmá-nyozása során megfigyelt összefüggésekrõl.…”

Artificial Carriers: A Strategy for Constructing Antigenic/Immunogenic Conjugates

“…These polypeptides are based on a poly(LLys) backbone and contain short side chains composed of three DL-Ala residues and one other amino acid residue (X), either at the end of the branches (XAK) or at the position next to the polylysine backbone (AXK) (Fig. 4) [52][53][54]. Emphasis was given on the structural characterization of these polymeric polypeptides, such as chemical analysis, size, primary structure (enantiomer composition and length distribution of the side chains) and solution conformation in relation to the biological activities attributed to the carrier function, immunoreactivity, immunomodulatory potential, biodegradation, in vitro cytotoxicity and biodistribution [55][56][57][58].…”