Chemical modification of kappa-elastin from bovine ligamentum nuchae

Spheroid organization kinetics of H35 rat hepatoma model cell system on elastin-like polypeptide-polyethyleneimine copolymer substrates

Though two-dimensional systems have yielded some success in deriving morphological and functional markers of hepatocyte culture, they largely fail to capture the three-dimensional organization, long-term viability, and functionality of the hepatic tissue. We have engineered a system for inducing self-assembly of model H35 rat hepatoma spheroids using a copolymer comprised of biocompatible elastin-like polypeptide (ELP) chemically conjugated to positively charged polyethyleneimine (PEI). We have achieved a conjugation ratio of 30 mol %, though our studies analyzing spheroid organization kinetics indicate conjugate ratios of 5 mol % and greater to be optimal for cell culture based on least variability in spheroid sizes and minimum incidence of overgrown aggregates. Furthermore, our ELP-PEI system indicated the potential for influencing ultimate spheroid dimensions, with spheroid size inversely related to polyelectrolyte conjugation. Overall, this study provides a good starting point to investigate functional correlations between spheroid size and functional markers and their future use as an in vitro diagnostic or tissue engineering tool.

Cellular response to nanoscale elastin-like polypeptide polyelectrolyte multilayers

Ionic elastin-like polypeptide (ELP) conjugates are a new class of biocompatible, self-assembling biomaterials. ELPs composed of the repeat unit (GVGVP)(n) are derived from the primary sequence of mammalian elastin and produced in Escherichia coli. These biopolymers exhibit an inverse transition temperature that renders them extremely useful for applications in cell-sheet engineering. Cationic and anionic conjugates were synthesized by the chemical coupling of ELP to polyethyleneimine (PEI) and polyacrylic acid (PAA). The self-assembly of ELP-PEI and ELP-PAA using the layer-by-layer deposition of alternately charged polyelectrolytes is a simple, versatile technique to generate bioactive and biomimetic surfaces with the ability to modulate cell-substratum interactions. Our studies are focused on cellular response to self-assembled multilayers of ionic (GVGVP)(40) incorporated within the polymeric sequence H(2)N-MVSACRGPG-(GVGVP)(40)-WP-COOH. Angle-dependent XPS studies indicated a difference in the chemical composition at the surface ( approximately 10A below the surface) and subsurface regions. These studies provided additional insight into the growth of the nanoscale multilayer assembly as well as the chemical environment that the cells can sense. Overall, cellular response was enhanced on glass substrata coated with ELP conjugates compared with uncoated surfaces. We report significant differences in cell proliferation, focal adhesions and cytoskeletal organization as a function of the number of bilayers in each assembly. These multilayer assemblies have the potential to be successfully utilized in the rational design of coatings on biomaterials to elicit a desired cellular response.

Photolysis and partial ozonolysis of kappa-elastin from ligamentum nuchae

Photolysis and partial ozonolysis of guanidinated kappa-elastin led to the destruction of isodesmosine and desmosine up to 96.0 and 91.5% respectively. Simultaneously there was a 3.89-fold enrichment of the lysine content. Two lysine containing tripeptides and one dipeptide were isolated and characterized. Their amino acid sequences were Gly-Ala-Lys, Gly-Lys-Ala and Lys-Ala, respectively.

A compilation of amino acid analyses of proteins. XVIII. Residues per thousand residues--5

The amino acid analyses of 213 proteins, as residues per 1000 residues, are given. In addition, the carbohydrate content, the content of any noncommon amino acids, the sources of all proteins, and the necessary literature citations are given.

Guanidination of the lysine residues present in fibrous elastin and in soluble elastin peptides

We have found that only 20 to 30% of the lysine residues measured after acid hydrolysis of insoluble elastin and alpha-elastin were blocked by prior guanidination of elastin with o-methylisourea. In contrast free lysine was guanidinated almost 100% and a purified, highly crosslinked peptide fraction of low molecular weight, 85%. The non-reactivity of lysine does not seem to be due to steric hindrance in the fibrous protein or in the large peptides derived therefrom but rather to the presence of epsilon [delta-adipic acid]-lysine, the oxidized form of lysinonorleucine described by Bailey et al. Since photolysis of desmosine and isodesmosine leads also to the formation of new lysine residues, methods will have to be devised to distinguish lysine-containing peptides derived from photolyzed elastin.