Branched Chain Polypeptide

Hudecz, F. Design of synthetic branched-chain polypeptides as carriers for bioactive molecules. Anticancer Drugs 6 171-193, 1995. 

Mezo, G., Mrhala, N., Andreu, D., and Hudecz, F. (2000) Conjugation of epitope peptides to branched chain polypeptides via Cys(Npys). Bioconjugate Chemistry 11, 484- 91. 

Perkins, A. C., Frier, M., Pimm, M. V., Hudecz, F., 1998, c-branched-chain-polypeptide (BCP) A potential synthetic radiopharmaceutical. J. Labelled Comp. Radiopharm XLI 631-638. 

Pimm, M. V., Perkins, A.C., Gribben, S. J., Mezo, G., Gaal D and Hudecz, F. 1995 Gamma scintigraphy of In-labelled branched chain polypeptides (BCP) with a poly(L-lysine) backbone in mice with mammary carcinoma Effect of charge on biodistribution and tumour imaging potential. Annals. Nucl. Med., 9 247-251. 

Due to the good recovery of die polymers from the column, RP-HPLC was used with success for the detection of small molecular mass impurities and for the small-scale purification of branched chain polypeptides. Chromatograms are illustrated in Figure 2. 

As a result of the branched chain architecture, TASP molecules exhibit some unique conformational properties)5 12-14 47 75 76 148 For example, the folding to a compact state proceeds via two distinct steps the onset of secondary structure in the attached peptide blocks followed by their template-directed self-assembly to a three-dimensional packing topology. Due to its characteristic branched chain connectivity, the conformational space accessible in the unfolded state is considerably reduced compared to a linear chain of similar size (excluded volume effect), resulting in a smaller chain entropy. Thus, folded TASP molecules are expected to show higher thermodynamic stability compared to unbranched polypeptides of comparable size. 

Fig. 1. Schematic representation of branched-chain polymeric polypeptides.

For the preparation of multivalent epitope conjugates, branched-chain polymeric polypeptide (SAK) was reacted with chloroacetic acid pentachlorophe-... 

Hudecz, F., Kovacs, P., Kutassi-Kovacs, S., and Kajtar, J. (1984) GPC, CD and sedimentation analysis of poly-Lys and branched chain poly-Lys-poly-DL-Ala polypeptides. Colloid Polym. Sci. 262, 208-212. 

Carboxypeptidase A is an exopeptidase which specifically hydrolyzes C-ter-minal aromatic and branched chain aliphatic amino acids from di- and polypeptides. Dipeptides in which the N-terminal amino group is free are hydrolyzed only slowly, whereas the corresponding N-acylated dipeptides are rapidly hydrolyzed. The presence of an N-methyl group on the a-amino nitrogen of either the first, or the second amino acid residue of a polypeptide greatly suppresses the rate of hydrolysis 33, 34). Hanson and Smith 143) and Abramowitz et al. 144) have shown that the identity of the side chain residue in polypeptides of up to five amino acid residues in length influences the magnitudes of ifm and cat-... 

M. Ligeti, G. Mezo, K. Marko, E. Madarasz and F. Hudecz, Conjugation of a cyclic rgd derivative to branched chain polymeric polypeptide Synthesis and biological study of AK-(cyclo[RGDfC])),/. Peyt. Sci., 12,178 (2006). 

B. Evidence for Immunodominant Groups in Synthetic Polypeptides with Branched Chains (Multichain Copolymers)... 

PCCase is a biotinylated protein that catalyzes a reaction required in the catabolism of amino acids and fatty acids of odd-numbered chain length, and in the catabolism and anabolism of branched-chain fatty acids. In order to characterize the structure of this enzyme from plants we undertook its purification. PCCase activity was purified from extracts of maize leaves by a four step scheme that included PEG precipitation, hydrophobic interaction chromatography, anion exchange chromatography and affinity chromatography. This purification scheme achieved a nearly 250-fold purification of PCCase activity. However, throughout this purification of PCCase, ACCase copurified. Indeed, SDS-PAGE analysis of the final purified PCCase preparation identified two biotinylated polypeptides of about 240 and 230 kDa. These polypeptides have previously been described as subunits of ACCase (7). Furthermore, mixed substrate kinetic studies (8) with the purified PCCase/ACCase preparation indicated that the carboxylation of propionyl-CoA and acetyl-CoA were carried out by the same enzyme. Furthermore, both PCCase and ACCase activities were similarly affected by a variety of inhibitors. 

Proteins are linear polypeptides, and composed of amino acids. There are twenty different amino acids, and each amino acid has the same basic formula as shown in Fig. 2. Amino acids contain at least one carboxyl (-COOH) group and one amino (-NH2) group attached to the same carbon atom, called an alpha-carbon, and a variable R group. The side group (R group), which is different in different amino acids, can be a hydrogen atom, an unbranched or branched chain of atoms, aliphatic or aromatic... 

Schematic structure of branched chain polymeric polypeptides is shown in Figure 1. Polylysine with free s-amino groups, AK or poly [Lys(SerrDL-Alam)], (SAK) containing a-amino groups and poly[Lys(Omi-DL-Ala d], (OAK) possessing both a- and e-amino groups can be considered as polycations. Side chains of poly [Lys(Glui-DL-Alam)], (EAK) contains glutamic acid at the end of the branches. Therefore this polymer has not only free a-amino, but also free y-carboxyl group in the side chain, consequently this compound has amphoteric character. Acetylation of EAK resulted in a polyanionic derivative poly [Lys(Ac-Glui-DL-Alam)], (Ac-EAK).

Figure 52-6. Diagrammatic representation of the structures of the H, A,and B blood group substances. R represents a long complex oligosaccharide chain, joined either to ceramide where the substances are glycosphingolipids, or to the polypeptide backbone of a protein via a serine or threonine residue where the substances are glycoproteins. Note that the blood group substances are biantenna ry ie, they have two arms, formed at a branch point (not indicated) between the GIcNAc—R, and only one arm of the branch is shown. Thus, the H, A,and B substances each contain two of their respective short oligosaccharide chains shown above. The AB substance contains one type A chain and one type B chain.

Type IV collagen subtype [ctl(IV)]2Q 2(IV) from bovine lens capsule forms a fine meshwork structure containing many branches with about 20 nm between the branching points. There are three types of supramolecular assembly of type IV collagen molecules dimer formation (with six polypeptide chains) at the C-terminal NCI domain, the association of four molecules (12 chains) in a 30 nm tetramer formation at the N-terminal 7S domain, and lateral interaction at the collagenous domain (Figure 5(a)). ° ... 

The bulk of all carbohydrates in nature exists in the form of polysaccharides. These are very large molecules formed by linking together long chains of monosaccharide units. These chains may be linear, like polypeptides or polynucleotides, or branched. They may contain a single type of monosaccharide unit, similar to polyglycine or polyA for example, or two or more types of monosaccharide, like nucleic acids (four types of nucleotides) or proteins (20 types of amino acids). However, polysaccharides that contain more than two types of monosaccharide are rare in nature. 

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