Synthesis of and Structural Studies on Repeating Sequences of Abductin

Abstract

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.

Circular dichroism studies on repeating polypeptide sequences of abductin

“…1 In TFE-d 3 /H 2 O, a turn in the FGGM sequence is proposed. As a matter of fact, the temperature coefficient of M 4 NH is 4.2 ppb/K and strong sequential d NN NOEs between G 3 and M 4 are evident, thus suggesting in this case the presence of a type-I b-turn, 21 spanning the sequence FGGM.…”

“…Accordingly, for the FGGM sequence a temperature coefficient of 4.5 ppb/K was found for amide proton of M 4 , suggesting its involvement in a H bond. 21 For the GMGG sequence, the presence of d aN (i,i+2) NOEs between residue i+1 and i+3 of the turn is the main support for the turn structure. However, the temperature coefficient value is 5.1, thus suggesting an open turn without hydrogen-bond stabilization.…”

Investigating by CD the molecular mechanism of elasticity of elastomeric proteins

“…45 In the abductin extracted from the ligament of Placopecten magellanicus, the amino acid analysis revealed the presence, among others, of methionine and homocysteine, the last one being considered a cross-link precursor. 46 As a matter of fact, the ligament of Pecten fumatus fumatus, an Australian species with a similar composition to that of Placopecten, showed the N-terminus after cleavage with aminopeptidase M to contain a sequence, with two homocys- teines. Those result suggested the presence of disulfide crosslinks, originated by homocysteines, which in the oxidative environment of sea water is very stable (Table 1).…”

From bouncy legs to poisoned arrows: elastic movements in invertebrates

“…Recombinant abductins from multiple species are pure samples that are free of calcification and shape effects and can thus be used to determine the role, if any, of the subtle variations in amino acid sequences and compositions between scallop abductins (Denny and Miller, 2006) on material properties. Although fragments of abductin sequences from a single scallop species have been produced (Bochicchio et al, 2005), no full-length recombinant abductins have been generated to date. Nonetheless, this molecular-level approach is likely to reveal both the mechanisms for elastic behavior in biological proteins and also how biological systems have varied elastic behavior over evolutionary timescales.…”