Characterization of Products from the Reactions ofN-Acetyldopamine Quinone withN-Acetylhistidine

Xu, Rongda; Huang, Xin; Morgan, Thomas D.; Prakash, Om; Kramer, Karl J.; Hawley, M. Dale

doi:10.1006/abbi.1996.0191

Cited by 47 publications

(53 citation statements)

References 3 publications

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“…In insect cuticles, the nucleophilic attack of phenolic rings by His residues usually occurs at the 5-and 6-positions (19,27) whereas the C2 carbon is also targeted in model studies (35). Our data suggest that the C2 carbon is coupled to the His imidazole in the hydrolyzed dimer.…”

Section: Discussionmentioning

confidence: 72%

Cross-linking Chemistry of Squid Beak

Miserez

Rubin

Waite

2010

Journal of Biological Chemistry

104

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In stark contrast to most aggressive predators, Dosidicus gigas (jumbo squids) do not use minerals in their powerful mouthparts known as beaks. Their beaks instead consist of a highly sclerotized chitinous composite with incremental hydration from the tip to the base. We previously reported L-3,4-dihydroxyphenylalanine (dopa)-histidine (dopa-His) as an important covalent cross-link providing mechanical strengthening to the beak material. Here, we present a more complete characterization of the sclerotization chemistry and describe additional cross-links from D. gigas beak. All cross-links presented in this report share common building blocks, a family of di-, tri-, and tetra-histidine-catecholic adducts, that were separated by affinity chromatography and high performance liquid chromatography (HPLC) and identified by tandem mass spectroscopy and proton nuclear magnetic resonance ( 1 H NMR). The data provide additional insights into the unusually high cross-link density found in mature beaks. Furthermore, we propose both a low molecular weight catechol, and peptidyl-dopa, to be sclerotization agents of squid beak. This appears to represent a new strategy for forming hard tissue in animals. The interplay between covalent cross-linking and dehydration on the graded properties of the beaks is discussed.Cephalopods such as squids, cuttlefish, and octopods are equipped with a hard beak that is as sharp as a knife and crucial for disabling prey and feeding. Beak chemistry has attracted much recent attention in materials science: in contrast to mammalian hard tissues, the beak is devoid of minerals, consisting instead of a composite of proteins and chitin fibers with varying degrees of hydration along the beak structure. In animals, this is a unique material design for hard tissues that function in biting. The Dosidicus beak biocomposite possesses a stiffness (elastic modulus, E) of 5 GPa at the distal tip that decreases incrementally to 50 MPa (wet conditions) in the proximal wing, which is tightly embedded within the muscular buccal mass (1). As the beak lacks any of the known strengthening entities previously associated with wear-resistant tissues such as biomineralization (2-5), metal ion cross-linking (6, 7), or protein halogenation (8, 9), it begs a question, namely, what sort of molecular processing can impart such impressive physical properties? A deeper understanding of the mechanisms by which beaks are sclerotized is also likely to reveal novel chemical paradigms for the fabrication of robust and biocompatible composites for a variety of restorative applications. Furthermore, synthesis of such polymer-based composite materials could inspire environmentally friendly routes as Dosidicus beak is formed under ambient seawater conditions and is wholly nontoxic.From a biochemical perspective the biomaterial most similar to Dosidicus beak is hard insect cuticle. Both are predominantly composed of chitin fibers, protein, and polyphenolic compounds (10, 11). In insect cuticle, the contribution of dehydration and cross-...

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Section: Discussionmentioning

confidence: 72%

Cross-linking Chemistry of Squid Beak

Miserez

Rubin

Waite

2010

Journal of Biological Chemistry

104

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“…Potential cross-linking sites, however, abound in the His-rich domains, where two types of cross-links can be envisaged. One is a Michael-type addition product between DOPA-quinone and His or Lys (33,34). The presence of peptidyl-DOPA in preCol-D and catechol oxidase in byssus (35) makes formation of these likely upon maturation.…”

Section: Resultsmentioning

confidence: 99%

Tough Tendons

Xx¹,

Coyne²,

Jh³

1997

Journal of Biological Chemistry

133

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The primary structure of the ␣-chain of preCol-D (molecular mass ‫؍‬ 80 kDa), a tanned collagenous protein predominating in the distal portion of the byssal threads of the mussel Mytilus edulis, was deduced from cDNA to encode an unprecedented natural block copolymer with three major domain types: a central collagen domain flanked by fibroin-like domains and followed by histidine-rich termini. The fibroin-like domains have sequence motifs that strongly resemble the crystalline polyalanine-rich and amorphous glycine-rich regions of spider dragline silk fibroins. The terminal regions resemble the histidine-rich domains of a variety of metalbinding proteins. The silk domains may toughen the collagen by increasing its strength and extensibility. PreCol-D expression is limited to the mussel foot, which contains a longitudinal gradient of preCol-D mRNA. This gradient increases linearly in the proximal to distal direction and reaches a maximum just before the distal depression of the foot.Marine mussels Mytilus edulis produce byssal threads to attach to solid surfaces in the turbulent intertidal zone. Each thread is stiff at one end and extensible at the other. Molecular gradients correlated with a stiff-to-extensible mechanical gradation exist along the length of each thread (1, 2). Byssal threads (Fig. 1A) are often compared with tendons on the basis of their construction from anisotropically oriented bundles of collagen fibrils (3). Indeed, the distal portion of byssus and tendon share a roughly similar tensile strength and initial stiffness (4), but the similarity ends there. Byssal threads are at least five times more extensible and five times tougher than Achilles tendon (5). Moreover, unlike tendon, byssal threads have a nonperiodic microstructure and shrinkage and melting temperatures in excess of 90°C (6). Understanding how byssal collagen differs from other collagens is a critical first step to appreciating its role in the material performance of byssus.The characterization of byssal collagens has long been thwarted by the intractable cross-linked nature of byssus. Two independent lines of evidence, however, have hinted at an unusual possibility: that byssal collagen may be endowed with some qualities of a silk fibroin-like structure. The first evidence is based on wide-angle fiber x-ray diffraction of byssal threads of Mytilus edulis. The distal part consistently exhibits a typical collagen diffraction pattern with the notable addition of strong equatorial reflections at 4.5-4.6 Å and nonaxial arcs at 3.7-3.8 Å (2, 7). These prompted Rudall (7) to suggest the presence of a ␤-phase in the byssal collagen or an additional ␤-protein in the distal portion of byssus.In the second line of evidence, byssal threads of M. edulis were subjected to acid extraction coupled with extensive pepsinization. This approach solubilized two collagenous fragments, Col-P 1 and Col-D (both apparently homotrimers), predominating at the proximal and distal end of each thread, respectively (1). Precursors of these fragments, preCol-P ...

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“…In addition, quinones may also form unstable methide derivatives that crosslink cuticle proteins through the quinone side chain (Saul and Sugumaran, 1988). This reaction, known as β-sclerotization, involves dibasic residues, such as histidine (Xu et al, 1996) and is primarily responsible for cuticle hardening. Ultrastructural studies have revealed that cuticle is formed of superposed layers.…”

Section: Basic Structure Of the Larval Cuticlementioning

confidence: 99%

Genetic control of epidermis differentiation in Drosophila.

Payre¹

2004

Int. J. Dev. Biol.

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In arthropods, the animal body is isolated from the external environment by a protective exoskeleton called the cuticle. The cuticle of young larvae has certainly been the most scrutinized structure in Drosophila and genetic studies of the pattern of cuticular extensions has provided the main source of our comprehension of the control of embryonic development. However, the complex structure of the cuticle remains poorly understood and analysis of the underlying epidermis has started only recently. Here I review different aspects of epidermis differentiation with the aim of presenting an integrated view of the organisation of the Drosophila integument. Although profound differences in epidermis organisation are observed across species, accumulated results suggest that epidermis formation and differentiation might share an unsuspected number of homologies between Drosophila and vertebrates.

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Characterization of Products from the Reactions ofN-Acetyldopamine Quinone withN-Acetylhistidine

Cited by 47 publications

References 3 publications

Cross-linking Chemistry of Squid Beak

Cross-linking Chemistry of Squid Beak

Tough Tendons

Genetic control of epidermis differentiation in Drosophila.

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