Protein in fish

Vitvitsky, V.N. (1977). Comparative investigation of thermoresistance and electrophoretic lability of muscle proteins in fish habituated to different depths (In Russian). Ecologya 1977 (6), 88-92. 

Dyer, S.D., K.L. Dickson and E.G. Zimmerman. A laboratory evaluation of the use of stress proteins in fish to detect changes in water quality. In Environmental Toxicology and Risk Assessment, edited by W.G. Landis, J.J. Hughes and M.A. Lewis, Philadelphia, ASTM Publishers, 273 pp., 1993. 

Arukwe, A. and A. Goks0yr. Eggshell and egg yolk proteins in fish hepatic proteins for the next generation oogenetic, population, and evolutionary implications of endocrine disruption. Comp. Hepatol. 2 1-21, 2003. 

Methods. Early investigations relevant to technological analyses of the freezing operations involved determining the amount of protein extractable in salt solutions, such as 5% NaCl or 0.6M KC1. Proteins extracted in this manner were defined as native or undenatured. Then a question arose concerning the mechanism by which denaturation occurs. Unfortunately, denatured proteins are difficult to study because of their insolubility thus information about the state of proteins in fish had to be gained from the soluble protein fraction. 

Pascual CY, Crespo JP, Dominguez Noche C, Ojeda I, Ortega N, Martin Esteban M (1996). IgE-binding proteins in fish and fish steam. Monogr. Allergy, 32 174—180. 

The proteins in fish muscle tissue can be divided into three groups ... 

The protein in fish is denatured by the low pH of lime juice. Notice that the flesh shown with the limes has turned white compared with the flesh at normal pH. 

The proportion of myofibrillar proteins in fish total protein is higher than in mammalian muscle tissue, however the proportions among individual components (Table 13.7) are similar (cf. 12.3.2.1). The heat stability of fish proteins is lower than that of mammals, the protein denatu-ration induced by urea occurs more readily, and protein hydrolysis by trypsin is faster (Fig. 13.2). These properties provide additional evidence of the good digestibility of fish proteins. Mollusks contain paramyosin. The percentage of this protein in smooth muscles, e. g., of oysters, is 38%. 

In general, nonconventional protein foods must be competitive with conventional plant and animal protein sources on the bases of cost delivered to the consumer, nutritional value to humans or animals, functional value in foods, sensory quality, and social and cultural acceptability. Also, requirements of regulatory agencies in different countries for freedom from toxins or toxic residues in single-cell protein products, toxic glycosides in leaf protein products, pathogenic microorganisms, heavy metals and toxins in fish protein concentrates, or inhibitory or toxic peptide components in synthetic peptides must be met before new nonconventional food or feed protein products can be marketed. 

Other Proteins. Groundnut, fish, and cottonseed proteins have been used to a limited degree in dairy substitutes. The properties of the materials are discussed in thehterature (5). 

Female sexual development and behaviour in mammals occurs by default and requires no ovarian secretion, and it is only in genetic males that the testis can secrete hormones which destroy this female pattern and superimpose that of the male. Sexual differentiation is not so well defined in fish, and larval exposure to both synthetic estrogens and androgens is widely used in aquaculture to produce monosex cultures. Endocrine disruption of sexual differentiation in fish may therefore reflect both the complexity and diversity of such processes between different species. Some care is required in use of the terms hermaphrodite and sex-reversal since a true hermaphrodite has both functional testes and ovaries and a sex-reversed fish is fully functional as its final sex—both produce the appropriate viable gametes. Such functional sex-reversal is not possible in mammals, but in some species of fish it is the normal developmental pattern. In most of the cases of hermaphroditism or sex-reversal reported in the non-scientific press, there is evidence only for a few ovarian follicles within a functional testis. This may be considered as feminisation or a form of intersex, and is very clearly endocrine disruption, but it is certainly neither sex-reversal nor hermaphroditism. In some cases the terms have even been used to infer induction of a single female characteristic such as production of yolk-protein by males. 

FMNH2 requirement in bacterial luminescence Crystallization of Cypridina luciferin Crystallization of firefly luciferin Cypridina luciferin in fishes the first cross reaction discovered Structure of firefly luciferin Discovery of aequorin and GFP (green fluorescent protein) Structure of Cypridina luciferin Concept of photoprotein Structure of Latia luciferin Dioxetanone mechanism proposed in firefly and Cypridina luminescence... 

In terms of amino acids bacterial protein is similar to fish protein. The yeast s protein is almost identical to soya protein fungal protein is lower than yeast protein. In addition, SCP is deficient in amino acids with a sulphur bridge, such as cystine, cysteine and methionine. SCP as a food may require supplements of cysteine and methionine whereas they have high levels of lysine vitamins and other amino acids. The vitamins of microorganisms are primarily of the B type. Vitamin B12 occurs mostly hi bacteria, whereas algae are usually rich in vitamin A. The most common vitamins in SCP are thiamine, riboflavin, niacin, pyridoxine, pantothenic acid, choline, folic acid, inositol, biotin, B12 and P-aminobenzoic acid. Table 14.4 shows the essential amino acid analysis of SCP compared with several sources of protein. 

Various optical detection methods have been used to measure pH in vivo. Fluorescence ratio imaging microscopy using an inverted microscope was used to determine intracellular pH in tumor cells [5], NMR spectroscopy was used to continuously monitor temperature-induced pH changes in fish to study the role of intracellular pH in the maintenance of protein function [27], Additionally, NMR spectroscopy was used to map in-vivo extracellular pH in rat brain gliomas [3], Electron spin resonance (ESR), which is operated at a lower resonance, has been adapted for in-vivo pH measurements because it provides a sufficient RF penetration for deep body organs [28], The non-destructive determination of tissue pH using near-infrared diffuse reflectance spectroscopy (NIRS) has been employed for pH measurements in the muscle during... 

This area was the most profusely studied in the AQUATERRA project in terms of biological effects in fish populations. Barbel and bleak were the sentinel species selected in this area and an array of histological and biochemical tests were used to monitor the impact due to three major sources of pollution mercury and OCs at Monzon (with a comparison in one of the papers with Flix) and PBDEs in Barbastro [1—4, 37]. Mercury pollution was directly correlated to an increase of MTprotein in the liver of barbel captured downstream Monzon when compared to samples captured upstream (Fig. 3a). However, mRNA quantitative analyses failed to show any differences between downstream and upstream Monzon, neither correlated with MT protein levels. Further studies showed that MT mRNA in liver is a rather weak marker for chronic metal pollution in liver (see below) [4], The presence of degenerative hepatocytes in barbels and bleaks was also linked to mercury poisoning although it can also reflect the impact by other pollutants, like OCs or PBDEs (Fig. 3e). 

Tom M, Auslander M (2005) Transcript and protein environmental biomarkers in fish - a review. Chemosphere 59 155-162... 

The neurotrophins comprise a family of highly related molecules that act to support the survival and phenotypic specificity of select subsets of neurons. The neurotrophins (Table 27-2) are small highly basic proteins of approximately 13kDa that dimerize to form the biologically active species [5]. The neurotrophins have a highly conserved structure. This family includes five distinct members NGF,brain-derived neurotrophic factor (BDNF), neurotrophin 3 (NT3), neurotrophin 4/5 (NT4/5) and neurotrophin 6 (NT6). NT6 is found only in fish and will not be discussed further. 

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