Val-Val-Pro-Gln (valyl-valyl-prolyl-glutamine) is a small but highly conserved sequence present in all elastins. We describe its synthesis by mixed anhydride solution chemistry as an alternative to solid-phase peptide synthesis (SPPS). The molecular structure of the tetrapeptide in solution was investigated by classical spectroscopy, such as circular dichroism (CD), nuclear magnetic resonance (NMR) and Fourier Transform Infrared Spectroscopy (FTIR). The biological activity of Val-Val-Pro-Gln was evaluated by a bromodeoxyuridine (BrdU) incorporation assay with normal human dermal fibroblasts. This small peptide may play a critical role in control of matrix metabolism through its release from the elastin polypeptide chain during periods of tissue breakdown and remodelling. ((c) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005).

Little data exist on the structure and function of compressible elastomeric proteins such as abductin. An understanding of the underlying structural features of these proteins may lead to the development of a new class of highly tailored "compressible" hydrogels. To that effect, in this work, the structure of abductin was investigated by means of studies on several synthetic peptides corresponding to the most frequent sequences of abductin. In particular, the 10 amino acid abductin peptide sequence FGGMGGGNAG, tandem repeated in the protein, and two related 25 and 40 amino acid polypeptides were synthesized. These peptides were studied with regard to secondary structure, self-assembly, and polymer morphology. The results obtained with these peptides allow us to propose a preliminary structure-elasticity relationship for abductin not dissimilar from that currently accepted for elastin.A possible mechanism of elasticity relating abductin to elastin.

Background Antibodies (Abs) to α-elastin (elastin breakdown product) and tropoelastin (elastin precursor) are found in the serum of all human subjects and correlate with their respective serum peptide levels; however, peptide levels vary with age and some disease states. This study was undertaken to determine if serum elastin Abs, peptides, and elastin metabolism were altered in autoimmune diseases by detecting a changing ratio of serum anti-α:tropoelastin Ab levels. Methods Serum from patients with a variety of connective tissue diseases, including 28 with systemic lupus erythematosus (SLE), 24 with scleroderma, 18 with rheumatoid arthritis (RA), 10 with polymyositis, and 39 with vasculitis, was compared with serum from 19 age-matched healthy subjects for levels of antitropoelastin and anti-α-elastin Abs. Results We found an increase in IgG anti-α-elastin and a decrease in antitropoelastin Abs in the sera of patients with scleroderma (p < .02 and .00005) and SLE (p < .006 and .011). There was also a marked increase in anti-α-elastin Abs in patients with polyarteritis nodosa (p < .0005) and decreases in antitropoelastin Abs in patients with RA (p < .05), polymyositis (p < .01), and a variety of other vasculidities (p < .0003). Conclusions Abnormal variations in elastin metabolism may be detected in several connective tissue diseases by measuring ratios of α- and tropoelastin IgG Abs as markers of elastin degradation and synthesis.

The synthesis of two elastin sequences incorporating the structural unit X-G-G-X-G (X = A) is described. In particular, the following peptides and polypeptides were synthesized and characterized: TFA(-)H(2)(+)LGAGGAG-OH, TFA(-)H(2)(+)LGAGGAGVL-OH (both of these inducing stimulation of endogenous elastin production in cultured adult human fibroblast), poly(LGAGGAG), and poly(LGAGGAGVL). The synthesis was accomplished in solution by classical procedures, by using the diphenylphosphoryl azide for the polycondensation step, and the mixed anhydride method for the coupling steps. CD, NMR, and FT-IR measurements gave evidence of quasi-extended (PP II) structures as a peculiar structural feature in the heptapeptide, and a tendency towards flexible beta-turns in the nonapeptide. Poly(LGAGGAG) showed greater disorder with respect to the "monomer", the molecular conformation being accountable for by unstructured polypeptide chains together with beta-turns. The polymer is able to adopt supramolecular structures reminiscent of those found in elastin. Unlike that of the heptapeptide, polycondensation of the nonapeptide did not afford a linear polymer, but only cyclic derivatives, This could well be due to the tendency of the monomeric nonapeptide to adopt folded conformations.

High-resolution solid-state (13)C NMR spectra are presented for samples of alpha-elastin prepared from the aorta of normal and copper-deficient pigs. Chemical shifts of the various peaks indicate that both the normal and undercross-linked peptides have similar overall structures. However, (13)C T(1), (13)C T(1 rho), and (1)H T(1 rho) measurements indicate that the alpha-elastin peptides obtained from the abnormal elastic fibers samples exhibit altered mobilities, particularly in their side chains. Results from spectra taken with a range of contact times and from dipolar dephasing experiments are consistent with conclusions reached with the relaxation measurements. Namely, the loss of function associated with the undercross-linked sample is correlated to a small but measurable difference in relative mobility.

The human fetal membranes provide a sterile biomechanical container which adjust by growth to mid-pregnancy to the increase in fetal size, and by elasticity to the forceful movements of the fetus. The molecular basis for this elasticity is not known, yet reduced elasticity may lead to their premature rupture and preterm birth, a major problem in perinatal medicine. Classically, elastin confers the property of elastic recoil to elastic fibres which are assembled from a family of tropoelastin precursors. These are covalently cross-linked to form insoluble elastin by formation of desmosine and isodesmosine, catalysed by the enzyme lysyl oxidase. The amnion, chorion and decidua were shown by Northern analysis and RT-PCR to contain detectable levels of tropoelastin mRNA and the mRNA encoding lysyl oxidase. The proteins encoded by these mRNAs were also identified by Western blotting and immunolocalization. Further, insoluble elastin was extracted from the human fetal membranes and shown by comparison to elastin preparations from other elastic tissues to have a reasonable desmosine content. Finally, scanning electron microscopy confirmed the presence of multiple layers of an apparently very thin elastic system in this tissue. This biochemical and histopathologic study has demonstrated therefore that the human fetal membranes synthesize and deposit a novel elastic fibre. The presence of such an elastic system in these tissues provides, for the first time, a probable molecular basis for the elastic properties of this tissue.

Several overlapping cDNA clones were isolated from a lambda gtl0 cDNA library constructed using polyA+ RNA from neonatal sheep lung. DNA sequence analysis of these cDNA recombinants revealed the complete derived amino acid sequence of sheep tropoelastin. A comparison of DNA sequences from individual sheep tropoelastin cDNA also confirmed the presence of several tropoelastin mRNA isoforms in neonatal lung tissue.Coding domains corresponding to exons 13, 14 and 33 were present in several of the sheep tropoelastin cDNA fragments but absent in others. The relative amount of alternate usage of these exons was quantitated by polymerase chain amplification. In confirmation of previous studies in other mammalian species, extensive alternate usage of exon 33 was observed in total RNA isolated from aorta, nuchal ligament and pulmonary artery from neonatal sheep. In striking contrast to all previous studies, however, exons 13 and 14 were shown to be subject to almost the same level of alternate usage as exon 33 in all three neonatal sheep tissues examined.

Dietary lipid modulation of structural and passive mechanical properties of isolated rat abdominal aortic segments were assessed during the early developmental period. Rats were raised from conception to 90 days of age on semisynthetic diets containing various types and amounts of lipids. Aortic segments from three groups of rats fed high-fat diets (15%, wt/wt) consisting of olive oil, corn oil, or lard as the sole lipid sources were compared with those from rats fed a low-fat control diet containing corn oil (5%, wt/wt). Morphometric analysis of the tunica media demonstrated that rats raised on diets with a relatively low polyunsaturated fatty acid content (olive oil and lard) had greater numbers of elastic lamellae than rats raised on diets with opposite fatty acid indexes (high- and low-fat corn oil). Changes in elastin content of the tunica media, determined biochemically, paralleled those seen by morphometric analysis of the elastic lamellar number. Altered dietary fatty acid ratios were also associated with changes in smooth muscle cell number. In this regard, a decreased cellular density was observed in the olive oil and lard diets compared with the corn oil diet. The olive oil diet was unique amongst the dietary lipid regimens in raising, whereas the lard-containing diet lowered, indexes of aortic tissue elasticity. These results demonstrate an effect of chronic feeding of high dietary fat on the composition and biomechanical properties of the connective tissue matrix of abdominal aortic rings from young Sprague-Dawley rats.

The rat is notoriously resistant to vascular disease, but administration of haloperidol prenatally to the pregnant dam results in hyperlipidemic changes in F1 and F2 progeny. Total serum cholesterol concentrations in the F1 males reach levels three or more times greater than controls by one year of age. The phenomenon indicates a link between dopaminergic elements of the autonomic nervous system and cholesterol metabolism, a phenomenon heretofore unrecognized. Transfer of the hypercholesterolemia into the second generation further suggests that haloperidol induces a permanent change in the genetic control of lipoprotein metabolism. Although the observations are preliminary, they warrant consideration when administering the drug to pregnant women.