Protein cross-link, fish

Protein-Based Adhesives. Proteia-based adhesives are aormaHy used as stmctural adhesives they are all polyamino acids that are derived from blood, fish skin, caseia [9000-71 -9] soybeans, or animal hides, bones, and connective tissue (coUagen). Setting or cross-linking methods typically used are iasolubilization by means of hydrated lime and denaturation. Denaturation methods require energy which can come from heat, pressure, or radiation, as well as chemical denaturants such as carbon disulfide [75-15-0] or thiourea [62-56-6]. Complexiag salts such as those based upon cobalt, copper, or chromium have also been used. Formaldehyde and formaldehyde donors such as h exam ethyl en etetra am in e can be used to form cross-links. Removal of water from a proteia will also often denature the material. 

Fixation in formalin is suitable because the induced protein-protein and protein-nucleic acid cross-links preserve the tissue efficiently while retaining morphology relatively intact. However, the macromolecular network introduced by formalin significantly reduces the access of FISH probes to target DNA. Consequently, the initial steps in a FISH staining must address suitable breakdown of this network. 

Cho, Y.H., Shim, H.K., and Park, J. (2003). Encapsulation of fish oil by an enzymatic gelation process using transglutaminase cross-linked proteins. J. FoodSci. 68, TlYl-212 i. 

Leather can be defined as a material made from the outer skin of any vertebrate (fish, reptile, bird, mammal, etc.) by any process which renders it non-putrescible under warm, moist conditions. A true leather will retain this fundamental property even after repeated wetting and drying. These properties are imparted to the main constituent of the skin, the protein collagen, by introducing additional microbiologically-stable cross-links into the polypeptide structure. 

The chemical and physical properties of collagen proteins are different in tissues such as skin, swim bladder, and the myocommata muscle. In general, collagen fibrils form a delicate network structure with varying complexity in the different connective tissues in a pattern similar to that found in mammals. However, the collagen in fish is much more thermolabile and contains fewer, but more labile, cross-links than collagen from the warm-blooded vertebrates. 

Gan, C.Y., Cheng, L.H., Easa, A.M., 2008. Evaluation of microbial transglutaminase and ribose cross-linked soy protein isolate-based microcapsules containing fish oil. Innov. Food Set Emerg. Technol. 9, 563-569. 

The sulfhydryl groups and disulfide bonds play important roles in the functional and structural properties of heat-processed meat. During thermal processing, disulfide cross-linking of protein molecules may occur. This has been reported in fish, meat, squid, and seal (4-7). Sulfhydryl-dependent gelation of hen egg lysozyme at SO C has been demonstrated. These proteins had several intramolecular disulfide bonds with a good correlation between... 

A second possibility to increase the functionality of spray-dried emulsions is to build up a specific structure with desired functionality at the oil-water interface. Enzymatic cross-linking of proteins at the oil-water interface can increase the stability of emulsions. Cross-linking of a-lactalbumin at the interface of an emulsion increased the physical stability [28]. Kellerby et al. [29] investigated the influence of network formation through transglutaminase on the oxidation stability of caseinate-based fish oil emulsions. The authors showed that cross-linking increases the cohesiveness of the proteins at the interface but not lipid oxidation in liquid emulsions. Data from our own research showed that also in spray-dried microcapsules transglutaminase cross-linked proteins do not act as additional barrier (data not published). 

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