Occurrence of dityrosine in Tussah silk fibroin and keratin

Raven, David J.; Earland, Christopher; Little, Marjorie

doi:10.1016/0005-2795(71)90065-1

Cited by 98 publications

(58 citation statements)

References 10 publications

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“…Di-and trityrosyl residues are widely distributed in proteins, including resilin, the elastic protein in many arthropod ligaments (19), in silk fibroin and keratin of tussah silk moths (20), elastin (30) and another connective tissue protein from mammals (21), and in the adhesive discs of the sea mussel (31). Dityrosine has also been found in egg envelopes of dragonflies (22) and Drosophila melanogaster (32).…”

Section: Discussionmentioning

confidence: 99%

“…The reaction was started by adding enzyme, and the increase in absorbancy at 436 nm was monitored in a Gilford 420 spectrophotometer (11). All reported values are initial rates; the reaction slows after [15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30] sec. A unit of ovoperoxidase is that required to oxidize 1 'mol of guaiacol per min in a 1-ml assay volume.…”

Section: Methodsmentioning

confidence: 99%

“…(13,14) and to breakage by physical forces (15). We developed an assay to assess the effect of various compounds on the hardening process ( (19)(20)(21)(22)(23). They can be generated by the addition of horseradish peroxidase and H202 to solutions of tyrosine, tyramine, N-acetyl-L-tyrosine, or proteins containing tyrosyl residues (23)(24)(25).…”

Section: Methodsmentioning

confidence: 99%

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Release of ovoperoxidase from sea urchin eggs hardens the fertilization membrane with tyrosine crosslinks

Foerder

Shapiro

1977

Proc. Natl. Acad. Sci. U.S.A.

280

168

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One feature of fertilization is the alteration of the vitelline layer, by components released from the e, to produce an elevated, covalently crosslinked, hard, insoluble, fertilization membrane. The following evidence indicates that crosslinking and hardening are caused by the production of diand trityrosyl residues, by oxidation of protein-bound tyrosyl residues in thepresence of a peroxidase. Hardening of the fertilization membrane, as evidenced by its loss of solubility in 50 mM dithiothreitol, is inhibited by compounds known to inhibit many peroxidases. A peroxidase, here called the ovoperoxidase, is released from eggs at fertilization. This enzyme is, inhibited by the same compounds that inhibit hardening and at similar concentrations. Inhibitors of the ovoperoxidase and the hardening reaction include KCN, 3-amino-1,2,4-triazole, NaN3, phenylhydrazine, K4Fe(CN)o, sodium sulfite, and glycine ethyl ester. In addition, tyramine and N-acetyltyrosine both inhibit hardening, but O-methyltyrosine does not. Dityrosyl and trityrosyl residues are found in acid hydrolysates of isolated, hardened fertilization membranes. These residues have been identified by cellulose phosphate column chromatography, thin-layer chromatography, and amino acid analysis. The amino acid data have been used to estimate that there is one dityrosine crosslink per 55,000 daltons of protein.We suggest that, by catalyzing the crosslinking of tyrosyl residues, the ovoperoxidase leads to the production of a hard fertilization membrane that blocks the entry of additional sperm. Because peroxidases are spermicidal, a secondary function of the enzyme could be to kill sperm in the vicinity of the fertilized egg. Fertilization involves the union of two haploid genomes to make a new diploid individual. To ensure that only one sperm fertilizes an egg, many eggs become modified after penetration by the first sperm. In the case of the sea urchin Strongylocentrotus purpuratus, an immediate block to further sperm entry (polyspermy) is caused by a depolarization of the plasma membrane of the egg (1). After depolarization, the egg surface is rearranged by the cortical reaction (reviewed in refs. 2 and 3), in which secretory vesicles beneath the plasma membrane of the unfertilized egg release their contents in a massive exocytosis. A trypsin-like protease is released to cleave sperm receptors from the egg and thus serve as a second block. to polyspermy (3-5). During the cortical reaction, the vitelline layer that surrounds the egg elevates and is converted into a fertilization membrane. The fertilization membrane becomes altered in its morphology, solubility, and permeability in a discrete, multistep, assembly process that occurs in fixed sequence (6). This elevated structure is another block to sperm entry.The fertilization membrane is formed from the vitelline layer in a reaction with components released from the cortical granules (2, 3, 6). The structure thus produced is resistant to physical deformation (7), solubilization by protein denaturants (...

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Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Release of ovoperoxidase from sea urchin eggs hardens the fertilization membrane with tyrosine crosslinks

Foerder

Shapiro

1977

Proc. Natl. Acad. Sci. U.S.A.

280

168

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“…They reported that moisture in the silk enables enzymatic cleavage and oxidation of endogenous tanning phenols which in turn both changes the cocoon's colour and crosslinks protein chains, the latter having a strong effect on the mechanical properties of single silk fibres [27]. Whilst previous studies have used B. mori as a control for the presence of tanning [28] our results indicate that (5) 16 (1) 13 (7) 18 (3) 85 % 41 (2) 42 (1) 29 (6) 36 ( through careful modification of spinning conditions it may be possible to determine the agents and effects this discolouration has on the silkworm cocoon. These observations are of particular importance to agriculture as the quality and grading of cocoons is largely dependent on both size and purity [29][30][31].…”

Section: Discussionmentioning

confidence: 99%

Environmental effects on the construction and physical properties of Bombyx mori cocoons

2016

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Published studies of silks focus on processed fibres or the optimum conditions for their production. Consequently, the effects of the environment on the physical properties of the cocoon are either poorly understood or kept as closely guarded industrial secrets. In this study, we test the hypothesis that silkworms as ectothermic animals respond to environmental conditions by modifying their spinning behaviour in a predictable manner, which affects the material properties of the cocoons in predictable ways. Our experiments subjected spinning Bombyx mori silkworms to a range of temperatures and relative humidities that, as we show, affect the morphology and mechanical properties of the cocoon. Specifically, temperature affects cocoon morphology as well as its stiffness and strength, which we attribute to altered spinning behaviour and sericin curing time. Relative humidity affects cocoon colouration, perhaps due to tanning agents. Finally, the water content of a cocoon modifies sericin distribution and stiffness without changing toughness. Our results demonstrate environmentally induced quality parameters that must not be ignored when analysing and deploying silk cocoons, silk filaments or silk-derived bio-polymers.

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“…3À6 Moreover, sometimes such "Wild" cocoons are additionally stabilized by oxidative phenolic tanning, dityrosine cross-linking, and tannins derived from the caterpillar's food plant. 7,8 Mineralization is probably more important than the tanning in making Wild Silk cocoons difficult to soften and reel.…”

Section: ' Introductionmentioning

confidence: 99%

Demineralization Enables Reeling of Wild Silkmoth Cocoons

et al. 2011

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Wild Silkmoth cocoons are difficult or impossible to reel under conditions that work well for cocoons of the Mulberry silkmoth, Bombyx mori. Here we report evidence that this is caused by mineral reinforcement of Wild Silkmoth cocoons and that washing these minerals out allows for the reeling of commercial lengths of good quality fibers with implications for the development of the "Wild Silk" industry. We show that in the Lasiocampid silkmoth Gonometa postica, the mineral is whewellite (calcium oxalate monohydrate). Evidence is presented that its selective removal by ethylenediaminetetraacetic acid (EDTA) leaves the gum substantially intact, preventing collapse and entanglement of the network of fibroin brins, enabling wet reeling. Therefore, this method clearly differs from the standard "degumming" and should be referred to as "demineralizing". Mechanical testing shows that such preparation results in reeled silks with markedly improved breaking load and extension to break by avoiding the damage produced by the rather harsh degumming, carding, or dry reeling methods currently in use, what may be important for the development of the silk industries not only in Asia but also in Africa and South America.

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Occurrence of dityrosine in Tussah silk fibroin and keratin

Cited by 98 publications

References 10 publications

Release of ovoperoxidase from sea urchin eggs hardens the fertilization membrane with tyrosine crosslinks

Release of ovoperoxidase from sea urchin eggs hardens the fertilization membrane with tyrosine crosslinks

Environmental effects on the construction and physical properties of Bombyx mori cocoons

Demineralization Enables Reeling of Wild Silkmoth Cocoons

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