earticle

영어

Inhabitation on a boundary surface brings various advantages for organisms; such organisms therefore have developed a variety of molecular systems to hold themselves on boundary surfaces during their evolution. Marine sessile organisms are one of these that possess underwater attachment capability as an indispensable physiological function that allows them to live on a liquid-solid boundary during most of their life cycle. Recent advances in underwater holdfast studies on the mussel1] and barnacle,2] which represent two typical organisms demonstrating this kind of activity, have indicated that the biological adhesion is, in general, mediated by an insoluble multi-protein complex. Underwater attachment is a multi-functional process, including displacement of the bound-water layer on a foreign substratum by the adhesive, as well as spreading, coupling of the adhesive with a variety of material surfaces, self-assembly of the adhesive, curing to make the holdfast stiff and tough, and protection from microbial degradation. It remains unachievable technology and is considered to be based on a completely different approach from that used in developing man-made adhesives in air. The barnacle, a unique sessile crustacean, has long been noted for its underwater adhesion capability. The underwater adhesive material that is used, called cement, joins two different materials, the animal’s own calcareous base and the foreign substratum, together in water as a molecular event. The holdfast system of the barnacle has no similarity to that of mussel; no sequence similarity has been found among the protein components between the two systems. The mussel holdfast system depends on several protein modifications, including typical 3,4-dihydroxy phenylalanine (DOPA); however, no involvement of DOPA in the barnacle cement has been found. This presentation summarizes the characteristics of barnacle cement, and then compares the molecular systems between the barnacle and mussel to bring the natural concept into sharp relief. The design of self-assembling peptide material inspired by a cement protein, and the application of cement proteins as an adsorbent are also reported.