Structure and Mucoadhesion of Mussel Glue Protein in Dilute Solution

Abstract

Purified mussel adhesive protein mefp-1 (Mytilus edulis foot protein 1) has been studied regarding its state of oligomerization and gross conformation in dilute solution. Sedimentation equilibrium in the analytical ultracentrifuge of a dilute solution of protein (0.4 mg/mL) in acetate buffer at pH 4.5 and I = 0.10 M yielded an apparent molecular weight (whole distribution weight average, Mw, app) of 114 000 +/- 5000 via the "M" procedure, a value in almost exact agreement with the monomeric molecular weight obtained by MALDI mass spectrometry. At this low concentration, it is reasonable to assume thermodynamic ideality, i.e., Mw,app approximately Mw. This result, together with plots of point weight average apparent molecular weight versus concentration for three different loading concentrations (0.4, 0.8, 1.0 mg/mL), clearly demonstrates that this protein is essentially monomeric in dilute solution. Sedimentation velocity experiments yielded an estimate of the sedimentation coefficient s020,w = 2.34 +/- 0.17 S, which for M = 110 000 gives a frictional ratio f/f0 = 3.2 +/- 0.3. The interpretation of this, in terms of an extended rather than globular conformation for the structure of mefp-1 in dilute solution, is considered, within plausible limits of molecular hydration, and models for the structure in solution are considered, in light of the thermodynamic nonideality behavior of these molecules and previously published circular dichroism data. The significance of these observations in terms of the bioadhesive properties of mefp-1 is described, and the very strong interaction in dilute solution with a mucin glycoprotein is demonstrated.

Synthesis and Characterization of Self-Assembling Block Copolymers Containing Bioadhesive End Groups

“…PEO 100 PPO 65 PEO 100 (Pluronic F127, M h w ) 12 600) and PEO 78 PPO 30 PEO 78 (Pluronic F68, M h w ) 8400) were purchased from Sigma (St. Louis, MO). L-DOPA, thionyl chloride, N,N′-disuccinimidyl carbonate, sodium borate, sodium molybdate dihydrate, sodium nitrite, 1,6-diphenyl-1,3,5-hexatriene (DPH), 4-(dimethylamino)pyridine (DMAP), and purified bovine submaxillary mucin were purchased from Aldrich (Milwaukee, WI).…”

“…Highly concentrated solutions of certain PEO-PPO-PEO block copolymers, such as Pluronic F127 (PEO 100 PPO 65 -PEO 100 ) and F68 (PEO 78 PPO 30 PEO 78 ), exhibit sol-gel transitions when heated. [16][17][18][19] Polymer solutions possessing thermogelling and bioadhesive capabilities are potentially useful for medical and dental applications, [16][17][18][19][20] for example as tissue adhesives and as injectable carriers for drug delivery to mucosal surfaces (e.g., the oral cavity and the respiratory, gastrointestinal, and reproductive tracts).…”

Enhancement of poly(ethylene glycol) mucoadsorption by biomimetic end group functionalization

“…18 An atomic force microscopy ͑AFM͒-based approach was used by Cleary et al to probe the interaction force between a mucoadhesive polymer coated sphere and mucin 8 . Mussel adhesive proteins ͑MAPs͒ are interesting models for adhesive polymers, and in fact purified MAPs have been a͒ Author to whom correspondence should be addressed; electronic mail: philm@northwestern.edu previously reported to be highly mucoadhesive 19,20 . Although strong interactions between mucin and whole proteins extracted and purified from mussel adhesive plaques were found, the complexity inherent to whole proteins prevented the authors from attributing the observed mucoadhesive behavior to specific residues or functional groups present in the MAPs.…”

Strong reversible Fe 3+ -mediated bridging between dopa-containing protein films in water

“…Mytilus byssal cuticle contains moderate levels of Fe 3þ and a single protein-mussel foot protein-1 (mfp-1) (6). Mfp-1 has a mass of about 108 kDa in Mytilus edulis (7) and consists largely of tandem repeats of a positively charged decapeptide [AKPSYO*O-TY*K], in which O, O*, and Y* denote trans-4-hydroxyproline, trans-2, 3, cis-3, 4-dihydroxyproline, and 3, 4-dihydroxyphenylalanine (dopa), respectively (8). At pH 7.5, purified mfp-1 forms stable tris-and bis-catecholate complexes (log K s ∼ 43 at pH 7.5) with Fe 3þ in solution by way of its dopa side chains (the tris form is shown in Fig.…”