Rzepecki L M, Waite J H
College of Marine Studies, University of Delaware, Lewes 19958, USA.
Mol Mar Biol Biotechnol. 1995 Dec;4(4):313-22.
Marine and zebra mussels secrete byssal beards to attach themselves opportunistically to hard surfaces in their environment. By doing this, they naturally earn a reputation as fouling pests. The protein precursors of byssus in mussels are being investigated in the hope not only of discovering specific measures against these marine foulers, but also to gain some insights into the technically challenging task of engineering adhesive bonds underwater. Although byssal proteins are all part of the bearded glue that bonds them to a surface, they can be subdivided into three types depending on the function that they serve in byssal threads: (1) fibrous proteins form the load-bearing cables in the core of the threads, (2) cuticular proteins form a protective coat around the cables, and (3) adhesive proteins connect the cables to a foreign surface. A flaw in any one of these will undermine a mussel's ability to attach. The fibrous proteins can be collagenous, silk-like, elastic, or any combination of these. Covering these are the cuticular proteins, which are distinguished by their surface coupling properties, tandemly repeated primary sequence, and their high content of lysine and the exotic amino acid 3,4-dihydroxyphenyl-L-alanine (DOPA). The adhesive proteins are of low molecular weight, contain DOPA, and assemble to form microcellular solids (foams). Several of these proteins are already attracting biotechnological attention as cell and tissue attachment factors, anticorrosives, and metal-sequestering reagents.
海贻贝和斑马贻贝会分泌足丝须来随机附着在其生存环境中的坚硬表面上。正因为如此，它们自然而然地就成了污损害虫。贻贝足丝的蛋白质前体正在接受研究，这不仅是为了找到对付这些海洋污损生物的具体措施，也是为了深入了解在水下制造粘合剂这一技术难题。虽然足丝蛋白都是将贻贝与表面相连的带须胶水的一部分，但根据它们在足丝中所起的作用，可分为三种类型：（1）纤维状蛋白构成足丝核心的承重缆绳，（2）表皮蛋白在缆绳周围形成一层保护膜，（3）粘附蛋白将缆绳与异物表面相连。其中任何一种出现缺陷都会削弱贻贝的附着能力。纤维状蛋白可以是胶原质的、丝样的、有弹性的，或者是这些特性的任意组合。覆盖在这些蛋白之上的是表皮蛋白，其特点是具有表面偶联特性、串联重复的一级序列，以及高含量的赖氨酸和稀有氨基酸3,4-二羟基苯丙氨酸（DOPA）。粘附蛋白分子量低，含有DOPA，并组装形成微孔固体（泡沫）。这些蛋白中的几种已经作为细胞和组织附着因子、防腐剂和金属螯合剂引起了生物技术领域的关注。
