A,-casein

In the late 1800s, when the demand for coated paper for the halftone printing process increased, casein rapidly replaced glue. Casein forms a hard, tough film when dry, and can be waterproofed easily with formaldehyde (qv). The properties of soy protein are similar to those of casein, and soy protein has been substituted for it in many types of coated papers requiring a casein-type binder (see Soybeans and other oilseeds). Casein, a valuable food product, is seldom used as a paper adhesive, in spite of its excellent adhesive properties. 

Nitrogen sources include proteins, such as casein, zein, lactalbumin protein hydrolyzates such proteoses, peptones, peptides, and commercially available materials, such as N-Z Amine which is understood to be a casein hydrolyzate also corn steep liquor, soybean meal, gluten, cottonseed meal, fish meal, meat extracts, stick liquor, liver cake, yeast extracts and distillers solubles amino acids, urea, ammonium and nitrate salts. Such inorganic elements as sodium, potassium, calcium and magnesium and chlorides, sulfates, phosphates and combinations of these anions and cations in the form of mineral salts may be advantageously used in the fermentation. 

I. Ten pounds of AK-20 (a wettable powder with 20% DDT) and 4 ounces of a casein spreader per 100 gallons of water. 

Figures 9 and 10 represent a selected comparison of amide V and I+II FTIR and VCD for four proteins in D2O solution. Of these, myoglobin (MYO) has a very high fraction of a-helix, immunoglobulin (IMU) has substantial /1-sheet component, lactoferrin (LAF) has both a and j3 contributions, and a-casein (CAS) supposedly has no extended structure. The FTIR spectra of these proteins change little, the primary difference...

These conclusions were seriously questioned (21-24 and recent results indicate that the bioavailability of Ca2+ is the same from a casein diet as from a high-phytate soy concentrate (25). Oberleas contends that, in the presence of adequate amounts of Ca2+ and vitamin D, dietary phytate is not rachitogenic, even though it may bind substantial amounts of Ca2+ (J 5). This controversy, the relative paucity of available information, and the growing incidence of Ca2+ deficiency prompted us to investigate further the chemical interactions between Ca2+ and phytate and to assess its effect on the bioavailability of Ca2+ administered to mice by gavage. 

In addition to more rapid absorption of lipids in animals fed casein, another mechanism that may be operative is decreased clearance of circulating lipids. Rabbits fed a casein-based semipurified diet excreted significantly less cholesterol but more bile acids in their feces than animals fed a commercial diet (18). The total sterol excretion in feces of the animals fed the casein diet was half that of the rabbits fed the stock diet. Huff and Carroll (19) found that rabbits fed soy protein had a much faster turnover rate of cholesterol and a significantly reduced rapidly exchangeable cholesterol pool compared with rabbits fed casein. Similar studies performed in our laboratory revealed that the mean transit time for cholesterol was 18.4 days in rabbits fed soy protein, 36.8 days in rabbits fed casein, 33.7 days in rabbits fed soy plus lysine, and 36.3 days in rabbits fed casein plus arginine. These data suggest that addition of lysine to soy protein... 

Which of the following is polydisperse with respect to chain length (a) casein, (b) commercial PS, (c) paraffin wax, (d) cellulose, or (e) Hevea brasiliensisl... 

This can be seen in Fig. 3.6, where square-wave voltammograms for synthetic pictorial specimens contain recommended dosages [177] of lead white, plus (a) casein and (b) sunflower oil. As depicted in Fig. 3.3, the response of the pristine pigment consisted of a unique peak at -0.56 V. The pictorial specimens... 

Fig. 3.6 SQWVs for synthetic specimens containing lead white plus (a) casein and (b) sunflower oil, immersed into 0.50 M sodium acetate buffer, pH 4.85. Potential step increment 4 mV square wave amphtude 25 mV frequency 15 Hz [177]...

Figure 7.9 Effect of pectin (DE = 76%) on (a) creaming of protein-stabilized emulsions (11 vol% oil, 0.6 wt% protein, 0.28 wt% pectin, I = 0.01 M) containing (A) asi-casein (pH = 7), (A) p-casein (pH = 7), and ( ) o i-casein (pH = 5.5) and (b) steady-state shear viscometry of casein-stabilized emulsions (40 vol% oil, 2 vt% protein). Apparent shear viscosity at 22 °C is plotted against stress pH = 7.0, / = 0.01 M, (A) -casein, (A) p-casein, ( ) ocsi -casein + 0.5 wt% pectin, ( ) p-casein + 0.5 wt% pectin, ( ) p-casein + 1.0 wt% pectin, (O) as[-casein + 1.0 wt% pectin pH = 5.5,1 = 0.01 M, (x) ocsi -casein, (O) as[-casein + 0.5 wt% pectin, ( ) oc -casein + 1.0 wt% pectin. Reproduced from Semenova (2007) with permission.

In 1956, Waugh and von Hippel showed that the a-casein fraction of Hipp et al. contained two proteins, one of which was precipitated by low concentrations of Ca2 + and was called as-casein (s = sensitive) while the other, which was insensitive to Ca2+, was called /c-casein. as-Casein was later shown to contain two proteins which are now called a8l- and as2-caseins. Thus, bovine casein contains four distinct gene products, designated a5l-, x,2-, / - and /c-caseins which represent approximately 37, 10, 35 and 12% of whole casein, respectively. 

Although less susceptible than / - and as2-caseins, isolated xsl -casein in solution is also readily hydrolysed by plasmin. It has been suggested that a minor ill-defined fraction of casein, called A-casein, consists of plasmin-produced fragments of asl-casein, but the situation is unclear. 

Acid Casein B Casein A Casein B Casein A2 Casein A2 Casein A2 Casein A globulin A albumin B... 

Figure 7.15 Equilibrium water content of (a) casein micelles and (b) sodium caseinate and casein hydrochloride as a function of pH and changing water activities (isopsychric curves)...

Figure 10.3 Schematic representation of the rennet coagulation of milk, (a) Casein micelles with intact K-casein layer being attacked by chymosin (Q (b) micelles partially denuded of K-casein (c) extensively denuded micelles in the process of aggregation (d) release of macropeptides ( ) and changes in relative viscosity (0) during the course of rennet coagulation.

Materials and Methods. Fully deuterated phycocyanin and protio phycocyanin from Ph. luridum were used. The method of purifying phycocyanin was identical to that used previously (15, 16). The purity of the phycocyanin preparations, the complete substitution of deuterium for hydrogen in the fully deuterated phycocyanin, and the reversibility of the aggregation phenomenon were ascertained as previously (4, 16). Purified bovine trypsin, soybean trypsin inhibitor, and bovine liver catalase were obtained from the Worthington Biochemical Corp., Freehold, N. J., and used without further purification. Bovine a -casein B was kindly supplied by Chien Ho of the University of Pittsburgh. 

Literature values of sedimentation coefficients trypsin and soybean trypsin inhibitor (17) catalase (18) a,-casein B (JO). 

K-Caseins. The K-casein family comprises that portion of the a-casein fraction of Warner that is soluble in 0.4 M CaCl2 at pH 7.0 and 4°C and occurs as a mixture of polymers held together by disulfide bonds. An equilibrium is established between the polymers and monomers in a few hours (Vreeman et al. 1977). 

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