Caseins transglutaminases

In vitro, the enzyme is able to catalyze crosslinking of whey proteins, soy proteins, wheat proteins, beef myosin, casein, and crude actomyosin (which is refined from mechanically deboned meat), improving functional properties such as the texture of food products [49-53], Bonds formed by transglutaminase exhibit a high resistance to proteolytic degradation [54],... 

A method using transglutaminase for reducing the allergerricity of some food proteins and/or peptides has been developed as well, hf j-Casein (23 kDa) was treated with transglutaminase at 25°C for 20 h in water to manufactrrre cross-linked casein (approx. 90 kDa), which was less allergettic. 

A) Caserns cross-linked by die enzyme transglutaminase within the casein micelle ... 

The weak physical forces that hold together self-assembled nanoparticles are, of course, susceptible to disruption under the influence of thermodynamic and/or mechanical stresses. Hence some workers have investigated ways to reinforce nanoscale structures via covalent bonding. For instance, improved stability of protein nanoparticles, in particular, casein micelles, can be achieved by enzymatic cross-linking with the enzyme transglutaminase, which forms bonds between protein-bound glutamine and lysine residues. By this means native casein micelles can be converted from semi-reversible association colloids into permanent nanogel particles (Huppertz and de Kruif, 2008). 

Nonaka, M., Sakamoto, H., Toiguchi, S., Kawajiri, H., Soeda, T., and Motoki, M. 1992. Sodium caseinate and skim milk gels formed by incubation with microbial transglutaminase. J. Food Sci. 57, 1214-1218. 

Nonaka, M., Matsuura, Y., and Motoki, M. 1996. Incorporation of lysine dipeptides into asl-casein by Ca2+-independent microbial transglutaminase. Biosci. Biotechnol. Biochem. 60, 131-133. 

Bonisch, M.P., Lauber, S., and Kulozik, U. (2007). Improvement of enzymatic cross-linking of casein micelles with transglutaminase by glutathion addition. Int. Dairy J. 17, 3-11. 

Jimenez-Colmenero, F., Ayo, M.J., and Carballo, J. (2005). Physicochemical properties of low sodium iraiikfurler with added walnut effect of transglutaminase combined with caseinate, KCl and dietary fibre as salt replacers. Meat Science, 69,781-788. 

Pietrasik, Z., and Jarmoluk, A. (2003). Effect of sodium caseinate and K-carrageenan on binding and textural properties of pork muscle gels enhanced by microbial transglutaminase aAAitioa. Food Res. Int. 36, 285-294. 

Yan SB, Wold F. Neoglycoproteins in vitro introduction of glycosyl units at glutamines in beta-casein using transglutaminase. 52. Biochemistry 1984 23 3759-3765. 

Transglutaminase treatment of milk offers a novel way to improve the heat stability of milks without the use of chemical additives. Transglutaminase-treated milk had markedly improved heat stability at pH > 6.5 compared to untreated milk. This may be related to the effect of intramolecular cross-links formed in transglutaminase-treated milk, which prevents the dissociation of caseins from the micelles imder conditions where it would have otherwise occurred (e.g., when colloidal calcium phosphate is removed). This was considered to be the mechanism by which the enzyme-treated milk was stabilized to heat treatment (O Sullivan et al., 2002a,b). 

Schorsch, C., Carrie, H., Clark, A.H., and Norton, l.T. (2000a). Cross-linking casein micelles by a microbial transglutaminase conditions for formation of transglutaminase-induced gels. Int. Dairy J. 10, 519-528. 

Huppertz and Smiddy (2008) demonstrated that application of high pressure (250-300 MPa) led to an initial rapid micellar disruption this was followed by a partial reversal of the high-pressure-induced reassociation of micellar fragments. Partial internal cross-linking of casein micelles by transglutaminase prior to pressure treatment considerably slowed down both the disruption and reassociation processes. 

Glu)Lys bonds increase. It is interesting to note that if too much MTG is added, the firmness of the gel is decreased, an unexpected result. A gel formed with a ten percent caseinate solution treated with MTG 20 units/g protein at 37°C at pH 6.5 is weaker than a gel formed with MTG 15 units/g protein (Fig. 4). There may be a limit to the ability of -(7-Glu)Lys bonds to improve gel strength, and perhaps an excess of 6-(7-Glu)Lys bonds may weaken the gel stmcture. Such a gel formed with an excess of -(7-Glu)Lys bonds by use of transglutaminase becomes weak and has less water-holding capacity. Sometimes syneresis, a separation of liquid from a gel, is observed. We hypothesized that excess -(7-Glu)Lys bonds would inhibit uniform develpment of the protein network for entraining sufficient water. 

Figure 5 A flow diagram showing the deamidation of als-casein by transglutaminase. pHjSO refers to the protein isoelectric pH, and the percentages indicate the degree of modification. (From Ref. 53. Reprinted by permission.)...

Casein-based microcapsules produced by enzymatic gelation with transglutaminase... 

Heidebach, T., Forst, P., Kulozik, U. Transglutaminase-induced caseinate gelation for the microencapsulation of probiotic cells. Int. Dairy J. 19, 77-84 (2009)... 

Chambi, H., Grosso, C. Edible films produced with gelatin and casein cross-linked with transglutaminase. Food Res. Int. 39, 458-466 (2006)... 

Much work has also been carried out on non-cereal plant proteins. Solid-state H and NMR transverse relaxation measurements were used to investigate the effect of hydration on the plasticization of vicilin, legumin, and albumin fractions from peas. Their behaviour indicated that the plasticization of the globular legume proteins is considerably less than that found before for the linear barley protein C-hordein. The effects of microbial transglutaminase treatment on soy protein samples have been studied by H and solid-state NMR spectroscopy, and its relation to the glass transition temperature was examined. 2.83 Milk proteins have also been extensively investigated by NMR. 0 NMR spectroscopy has been used to study the effect of salt, temperature, and pH/pD on the hydration of bovine and caprine caseins. Furthermore, the addition of sucrose and lactose to casein solutions was shown to lead to increased casein... 

Figure 7 shows the SDS-PAGE profile of protein conjugates produced by transglutaminase-catalyzed crosslinking. Lanes 1 and 2 indicate that caseins (both a-casein and P-casein) are good substrates for transglutaminase. Almost... 

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