Circular dichroism studies of an elastin crosslinked peptide

Abstract

SynopsisCircular dichroic studies of a desmosine crosslinked peptide reveal a hitherto undescribed elastin spectrum possessing a weak negative band a t 230-235 nm, a weak positive band a t 215 nm, and a maximum negative band a t 190 nm. The spectrum is sensitive to both pH and temperature displaying increased ellipticity of the 215-nm band a t acidic pH and low temperature. The general shape of the spectrum and its behavior toward temperature changes suggest the presence of an extended helical conformation. Susceptibility of insoluble elastin to digestion with chymotrypsin is increased tenfold a t low temperature (doc), supporting the contention that the conformational change of the type described above occurs in insoluble elastin. Such changes in conformation would result in increased availability of aromatic amino-acid residues to peptide bond cleavage.

Determination of strain energy function for arterial elastin: Experiments using histology and mechanical tests

“…For example, X-ray analyses of elastin showed an absence of short-range order (Gotte et al, 1974), transmission electron microscopy studies revealed that elastin is amorphous (Albert, 1972), and polarized light microscopy demonstrated that single elastin fibers are optically isotropic (Aaron and Gosline, 1980). However, some researchers have argued that some level of order does exist within the polymer conformation (Foster et al, 1976;Pasquali-Ronchetti et al, 1979). Because of its insolubility, extensive crosslinking and hydrophobicity, the structure of elastin has proved difficult to determine.…”

Comparative structures and properties of elastic proteins

“…Studies of elastin indicate that the backbone is highly mobile (Ellis & Packer 1976) and that the alanine-rich domains that contain lysine residues for cross-linking are predominantly α-helical (Foster et al 1976). Urry and coworkers have carried out detailed studies of α-elastin and synthetic polypeptides corresponding to the major tetra-(VPGG), penta-(VPGVG) and hexa-(APGVGV) peptide consensus repeat motifs, demonstrating that β-turns were the predominant structural feature present.…”

Conformational Transitions of the Cross-linking Domains of Elastin during Self-assembly

“…Cross-linking domains can be separated into two specific sequence types, those consisting of lysines located within a proline-rich sequence (KP-type) or the more abundant type that contains polyalanine sequences interspersed with lysines in the form of KAAK or KAAAK (KA-type). KA-type cross-linking domains have been suggested to form an ␣-helical secondary structure that is believed to facilitate formation of crosslinks by bringing lysine residues together on the same face of the helix (4,(15)(16)(17)(18).…”