Elastin Cross-links

TLC. Aliquots of samples and standards were run on silica-coated thin layer chromatography (TLC) plates in either n-butanol/acetic acid/water (4 1 1 by vol. (BUOH/HAC/H2O)) or n-propanol/concentrated ammo-nia/water (8 1 11, pre-equilibration). These eluents were previously described (Keller et ah, 1984) for the two-dimensional TLC-separation of elastin cross-links. 

Brown-Augsburger, P., Tisdale, C., Broekelmann, T., Sloan, C., and Mecham, R. P. (1995). Identification of an elastin cross-linking domain that joins three peptide chains. Possible role in nucleated assembly./. Biol. Chem. 270, 17778-17783. 

Umeda, H., Takeuchi, M., and Suyama, K. (2001). Two new elastin cross-links having pyridine skeleton. Implication of ammonia in elastin cross-linking in vivo. J. Biol. Chem. 276, 12579-12587. 

Figure 2. Synthesis of mature elastin fibers. Some evidence suggests the possibility for proforms to elastin that appear as the first products of translation. These products are cleaved to tropoelastin (27), which appears to combine with microfibrillar protein. Although post-translational events important to the synthesis of the microfibrillar protein have not been defined, it is clear that it is a major component on which is organized or assembled the profibrillar forms of elastin. Cross-linking is catalyzed by lysyl oxidase, a copper-requiring protein (30). Recent information on the elastin proteinase(s) involved in tropoelastolysis would suggest that proteolysis may also play a role in elastin fiber...

Inhibition of lysyl oxidase disturbance of collagen and elastin cross-linking (see Section 13.3.3)... 

Figure I. Elastin cross-links formation. Lysine is converted into allysine via lysyl oxidase, which leads to the formation of lysinonor leucine and allysine aldol (blue). The spontaneous condensation between lysine and allysine will generate tetra-substituted desmosine and isodemosine cross-link structures (red). 

Narayanan, A. S., Page, R. C., Kuzan, F., and Cooper, C. G., 1978, Elastin cross-linking in vitro. Studies on factors influencing the formation of desmosines by lysyl oxidase action on tropoelastin, Biochem. J. 173 857-862. 

When a crude preparation of amine oxidase was added to the culture medium, the ratio of lysine to desmosine was decreased in aortas from both copper-deficient and copper-supplemented chicks. These experiments were a strong indication that a copper-dependent amine oxidase is involved in the elastin cross-linking process. 

Miller, E, J, Martin, E. R., Mecca, C. E., and Piez, K, A. (1965) The biosynthesis of elastin cross-links. The effect of copper deficiency and lathyrogen. J. Biol. Chem. 240 3623. 

Lysyl oxidase Collagen and elastin cross-linking... 

A star copolymer (SCP) of PCLA was synthesized by Younes and coworkers. This kind of SCP PCLA elastomer was also synthesized in two steps. First, the small molecular SCP was produced by ring-opening polymerization of s-caprolactone (s-CL) with glycerol as initiator and stannous 2-ethyUiexanoate as catalyst. Second, the living SCP was further reacted with different ratios of a cross-linking monomer, such as 2,2-bis(s-CL-4-yl)-propane (BCP) and s-CL. The SCP elastomers had very low glass transition temperature (—32°C). It was reported that the SCPs were soft and weak with physical properties similar to those of natural bioelastomers such as elastin. A logarithmic decrease in each tensile property with time was observed in this SCP PCLA. 

Miao M, Cirulis JT, Lee S et al (2005) Structural determinants of cross- linking and hydrophobic domains for self-assembly of elastin-like polypeptides. Biochemistry 44 14367-14375... 

Urry DW, Trapane TL, McMichens RB et al (1986) N-15 nmr relaxation study of inverse temperature transitions in elastin pol)q)entapeptide and its cross-linked elastomer. Biopolymers 25 5209-5228... 

After secretion from the cell, certain lysyl residues of tropoelastin are oxidatively deaminated to aldehydes by lysyl oxidase, the same enzyme involved in this process in collagen. However, the major cross-links formed in elastin are the desmosines, which result from the condensation of three of these lysine-derived aldehydes with an unmodified lysine to form a tetrafunctional cross-hnk unique to elastin. Once cross-linked in its mature, extracellular form, elastin is highly insoluble and extremely stable and has a very low turnover rate. Elastin exhibits a variety of random coil conformations that permit the protein to stretch and subsequently recoil during the performance of its physiologic functions. 

Elastin confers extensibihty and elastic recoil on tissues. Elastin lacks hydroxylysine, Gly-X-Y sequences, triple hehcal stmcture, and sugars but contains desmosine and isodesmosine cross-links not found in collagen. 

Lysine oxidase Cu Cross-links collagen and elastin... 

Some proteins, like collagen and elastin, have covalent cross-links between their fibres, which are formed after their synthesis (post-translational modification). 

Reiser K, McCormick RJ and Rucker RB (1992) Enzymatic and nonenzymatic cross-linking of collagen and elastin. FASEB J 6, 2439-2449. 

Keller S, Ghosh AK, Ghosh AK, Turino GM and Mandl I (1984) Separation of the cross-linking amino acids of elastin on thin-layer plates. J Chromatogr 305,461-464. 

Native elastin is an insoluble, highly cross-linked protein. The chemistry, properties and structure of elastin have been frequently reviewed in the past330-333. In this context, aspects of calcification processes will be discussed. 

Martino, M., and Tamburro, A. M. (2001). Chemical synthesis of cross-linked poly(KGGVG), an elastin-like biopolymer. Biopolymers 59, 29-37. 

Sandberg, L. B., Weissman, N., and Gray, W. R. (1971). Structural features of tropoelastin related to the sites of cross-links in aortic elastin. Biochemistry 10, 52-56. 

Vardaxis, N. J., Boon, M. E., and Ruijgrok, J. M. (1996). Calcification of cross-linked collagen-elastin membrane implants in vivo and their proposed use in bone regeneration. Biomaterials 17, 1489-1497. 

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