Poly acids cyanophycin

C3 Lactic acid 3-Hydroxypropionic acid Glycerol 1.2- Propanediol 1.3- Propanediol Propionic acid Acetone L-lsoleucine L-Leucine L-Proline L-Serine L-Valine L-Arginine L-Tryphophane L-Aspartic acid Cyanophycin Gellan Heparin Hyaluronic acid Poly-gamma-Glutamic acid Poly-epsilon-lysine Polyhydroxyalkanoates Pullulan... 

Berg, H., Ziegler, K., Piotukh, K., Baier, K., Lockau, W., and Volkmer-Engert, R. (2000) Biosynthesis of the cyanobacterial reserve polymer multi-L-arginyl-poly-L-aspartic acid (cyanophycin) Mechanism of the cyanophycin synthetase reaction studied with synthetic primers. Eur.J. Biochem., 267, 5561-5570. 

The third mechanism is represented by nonmodular one-step peptide synthesis. Enzymes belonging to this group catalyze the biosynthesis of poly(amino acids). Naturally occurring poly(amino acids) comprise cyanophy-cin [multi-L-arginyl-poly-(L-aspartic acid) cyanophycin granule polypeptide, (CGP)], (poly-(e-lysine) (PL), and poly-(y-glutamate) (PGA). As a consequence of non-ribosomal biosynthesis these peptides reveal a polydisperse mass distribution. 

Biosynthesis of the cyanobacterial reserve polymer multi-L-arginyl-poly-L-aspartic acid (cyanophycin). 

Richter R, Hejazi M, Kraft R, Ziegler K, Lockau W (1999), Cyanophycinase, a peptidase degrading the cyanobacteiial reserve material multi-L-arginyl-poly-L-aspartic acid (cyanophycin) - Molecular cloning of the gene of Synechocystis sp. PCC 6803, expression in Escherichia coli, and biochemical characterization of the purified enzyme , Eur J Biochem, 263, 163-199. 

Additionally, compounds such as a-arginyl aspartic acid dipeptide, modified cyanophycin containing less arginine, and poly-a,P-DL-aspartic acid were used as primers by the respective CphA [76],... 

For large-scale recombinant production of bacterial polymers, non-polymer producing bacteria were exposed to biosynthesis pathways. Polymers such as PHA, CGP (cyanophycin granule peptide), HA (hyaluronic acid), and PGA [poly-y-glutamate] were produced by these methods [89, 85-96]. For example, recombinant E.coli [89] was fermented for the lai e-scale production of PHA [89]. In addition the PHB biosynthesis genes of Ralstonia eutropa were harbored in E.coli to produce poljmers such as PHA composed of (R)-S-hydroxybutyrate and (R)-3-hydroxyvalerate and/or (R)-3-hydroxyhexanoate which showed preferable properties for use in industrial applications [97-99, 85-96]. 

Cyanophycin and Poly(Aspartic Acid)-Based Biomaterials... 

CYANOPHYCIN AND POLY(ASPARTIC ACID)-BASED BIOMATERIALS... 

Further, the material and physical properties of cyanophycin have not been well characterized, and hence, studies on the applications of cyanophycin as a biomaterial have been limited. A synthetic PAA similar to cyanophycin that has found biomedical applications is poly(aspartic acid). Poly(aspartic acid) is synthesized using various schemes, the most common being thermal polymerization of aspartic acid and polycondensation of carboxyanhy-drides. Poly(asparlic acid) has also been found to undergo biodegradation by lysosomal enzymes [302-305]. The... 

Proteins are composed of amino acids linked by peptide bonds. Two main biosynthetic pathways for protein production have been identified so far the ribosomal and the non-ribosomal-multi-enzyme paths. The proteins are mainly heteropolymers composed by a variety of amino acids however, three poly(amino acid)s can be obtained through the multi-enzyme pathway cyanophycin (aspartic acid-arginine dipeptide), s-poly-L-lysine and poly-a,p-aspartic acid (Figure 1.5). 

Natural poly(amino add)s, such as cyanophycin, poly( -L-lysine) and poly-y-glutamic acid, are biodegradable ionic polymers. These are polydispersed molecules that consist of a-amide linkages, P- and y-carboxylic groups and -amino groups. 

Cyanophycin granule polypeptide (CGP) is a microbial poly(amino acid) synthesized and sequestered as inclusion bodies by cyanobacteria [310] and other microorganisms [311]. CGP is composed of a poly(aspartic acid) (poly(Asp)) backbone chain with arginine (Arg) residues attached as pendant groups (Figure 2.41) [311]. 

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