Peptides from /3-casein

Maeno, M., Yamamoto, N., and Takano, T. 1996. Isolation of an antihypertensive peptide from casein hydrolysate produced by a proteinase from Lactobacillus helveticus CP790. J. Dairy Sci. 79, 1316-1321. 

Enzymatic cleavage of hydrophilic peptides from casein. 

Hydrolysis of Bitter Peptides from Casein by CPase Top. When a 0.5% solution of bitter peptides from casein was incubated with crude CPase Top (enzyme/substrate ratio = 2 /xkat/g), most of the bitterness was eliminated after 2 hr, but some bitterness remained even after 15 hr (Fig. 2). The liberated amino acids increased with time similarly as with the soy bitter peptides. 

Figure 2. Hydrolysis of bitter peptides from casein by CPase Top. Reaction conditions , 30°C, pH 4.0.

Gallagher et al. [138] investigated the future application of two enzymes, bromelain and a bacillus protease (Bacillus subtilis) in the production of peptides from casein in point of view of the functional properties of the products. Bromelain action resulted in a hydrolysate with a great number of high-molecular-mass peptides this may have improved the functional properties of a food product. The bacillus protease seemed to be more suitable for producing bitter peptides for future research and/or for future food. 

Henschen A, Lottspeich F, Brand F, Teschemacher H. Novel opioid peptides derived from casein (fi-casomorphins). Hoppe-Seyler s Z. Physiol Chem 1979 360 1217-1224. 

Chabance B, JoUes P, Izquierdo C, Mazoyer E, Francoual C, Drouet L, Eiat AM. (1995) Characterization of an antithrombotic peptide from kappa-casein in newborn plasma after milk ingestion. Br J Nutr 73 583-590. 

The electronic property of the amino acid on the C-terminus also has an effect on antioxidant activity (Li et al., 2011), that is, the larger the electronic property, the higher is the activity. The C-terminus is a polar position that is thus affected by its electrostatic potential, to some extent therefore, the amino acids Trp, Glu, Leu, lie, Met, Val, Tyr, etc. are suitable at the C-terminus. Some researchers have speculated that the identity of the amino acid on the C-terminus would play an important role in its activity. Suetsuna (2000) separated and identified a radical scavenging peptide, Tyr-Phe-Tyr-Pro-Glu-Leu, from casein hydrolysate, and it was confirmed that the Glu-Leu on the C-terminus mainly contributed to its antioxidant activity. Kim et al. (2009) speculated that the hydrophobic property of the amino acid on the C-terminus, for example, Val and Leu, had a distinct effect on the activity, as determined from the analysis of antioxidative peptides derived from venison hydrolysate. 

Although in vitro, the cell wall-associated proteinase of the Lactococcus starters is quite active on 8-casein (and that from some strains on asl-casein also), in cheese, they appear to act mainly on casein-derived peptides, produced by chymosin from asl-casein or by plasmin from / -casein. 

Peptides extracted from casein with N, N-dimethyl formamide have complex electrophoretic patterns identical to those of the fraction first prepared by Long and co-workers and called X-casein (El-Negoumy 1973). These peptides are identical electrophoretically to those released by the action of plasmin, which is present in fresh raw milk, upon asr casein (Aimutis and Eigel 1982). Two of these peptides have tryptic peptide maps and molecular weights identical to those of a pair of the peptides produced by plasmin degradation of asl-casein. These peptides appear to be fragments of a8l-casein which are present in milk as the result of plasmin proteolysis. More definitive information on their primary structure is needed before nomenclature for these fragments can be established. 

Yvon et al. (45) studied the solubility of 75 peptides from hydrolysates of casein in solutions of 1, 4, 8, and 12% trichloroacetic acid. They found 36 completely soluble peptides and 6 completely insoluble peptides at all concentrations of TCA and 30 peptides whose solubility fell as the TCA concentration rose. They attempted to relate solubility to size, hydrophobicity, and charge at a given pH and reported that solubility decreased with size in 2% TCA but was unrelated to molecular weight in 4, 6, and 12% TCA. 

Extraction of a portion of whey proteins, peptides, and amino acids Suitable for extraction of caseins and peptides from young cheeses. Not as effect as water Extraction of bitter and astringent peptides... 

Enzymatic hydrolysates of various proteins have a bitter taste, which may be one of the main drawbacks to their use in food. Arai el al. [90] showed that the bitterness of peptides from soybean protein hydrolysates was reduced by treatment of Aspergillus acid carboxypeptidase from A. saitoi. Significant amounts of free leucine and phenylalanine were liberated by Aspergillus carboxypeptidase from the tetracosapeptide of the peptic hydrolysate of soybean as a compound having a bitter taste. Furthermore, the bitter peptide fractions obtained from peptic hydrolysates of casein, fish protein, and soybean protein were treated with wheat carboxypeptidase W [91], The bitterness of the peptides lessened with an increase in free amino acids. Carboxypeptidase W can eliminate bitter tastes in enzymatic proteins and is commercially available for food processing. 

Umetsu, H., Matsuoka, H., and Ichishima, E. (1983). Debittering mechanism of bitter peptides from milk casein by wheat arboxypeptidase. J. Agric. Food Chem., 31, 50-53. 

As given in Table XII the Q-method was also successfully applied in the case of bitter peptides from the rennet-sensitive sequence of K-casein (36) ... 

Figure 2, Bitter peptides from aa,-casein ( ) = hydrophilic regions...

Most of the known bioactive peptides derived from milk proteins are opioid peptides (Table V). Those derived from caseins are called casomorphins or casoxins, while those from whey proteins are lactorphins, lactoferroxins or serorphin. Major opioid peptides are fragments of (3-casein. 

Meisel, H. and Frister, H. 1989. Chemical characterization of bio-active peptides from in vivo digests of casein. J. Dairy Res. 56, 343-349. 

Miclo, L., Perrin, E., Driou, A., Papadopoulos, V., Boujrad, N., Vanderesse, R., Boudier, J. F., Desor, D., Linden, G., and Gaillard, J.-L. 2001. Characterization of a-casozepine, a tryptic peptide from bovine asi-casein with benzodiazepine-like activity. FASEB J. ((Express Article 10.1096/fj.00-0685fje published online June 8, 2001)). 

In addition, peptides binding different minerals have been found in whey proteins, i.e., from (3-lg, a-la and LF. Since these proteins are not phosphorylated, the minerals seem to bind through other binding sites than caseins. Seventeen (17) different peptides have been identified by hydrolysis of (3-lg with thermolysin using two different concentrations of calcium. Also, peptides from a-la and LF using trypsin, chymotrypsin or pepsin have been reported. Studies with 3-lg and a-la peptides have shown a higher affinity for iron than the native proteins (Vegarud et al., 2000). 

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