Serum globulin, denaturation

In order to gain visual control during the electrophoretic migration, we have found the following technique satisfactory (W8). One indicator consists of a 35 % sol of dextran (mol. wt. 150,(XK)) colored a deep blue with bromophenol blue. A small drop is placed on the agar near the serum sample. Part of it will dye the serum albumin exclusively, since the serum globulins are only colored after denaturation. Thus, the albumin front will take on a pure bluish color and demonstrate anionic progress. 

The effects of divalent cations on bovine serum globulin in terms of salting-out and stabilization of the native form and salting-in and denaturation was studied by Arakawa and Timasheff (1984) in terms of the protein preferential hydration. This increased in the order Mn + Ni + < Ca + Ba + < Mg + < Na+ leading to increased salting-out and stability of the protein against denaturation. The binding of the divalent salts to the protein overcomes the ion exclusion from the surface due to competition for water of hydration. 

A retardation in the rate of denaturation of a pure protein in solution, comparable to the pressure effect on the thermal destruction of the luminescent system, thus assumes particular interest. Qualitative observations have recently shown that this phenomenon takes place in solutions of highly purified egg albumin and serum globulin (120). A pressure of 10,000 lb. per sq. in. practically pi events the precipitation of the latter protein at 65°C. and pH near neutrality. Quantitative studies of the kinetics of this denaturation have not been completely analyzed, but the indications are that a volume increase of activation on the order of 100 cc. per mole is involved (121). Small concentrations of ethyl alcohol accelerate the precipitation under both normal and increased pressure, as shown in Figure 17 the denaturation proceeds with a large volume increase of activation, of the order of 100 cc. per mole, as in the destruction of the... 

Globulin Human serum Denaturation 6.0 65 — Johnson and Campbell (1946)... 

Lactoglobulin With a denaturation temperature of 78°C, /3-lacto-globulin is the least denaturable of the serum proteins (Table 11.2). It exhibits a second thermal change near 140°C caused by a breakdown of disulfide bonds and additional unfolding of the molecule (de Wit 1981 Watanabe and Klostermeyer 1976). A change in pH between 6 and 7.5 shifts denaturation between 78° and 140°C, the total denaturation at the two temperatures being nearly constant. pH 6 favors dena-... 

Many proteins are very rapidly denatured so that ideally the fluid should be analyzed immediately. (32-Globulin fractions are partially lost when the serum is kept for some days (03). In work with lipoproteins, refrigeration alters the results (HI, Hla), but preservation in a deep freezer is practical for reference work. 

El-FFF is a technique devoted to the fractionation of proteins which is reflected in the number of papers applying this technique to protein separations. The possibilities of El-FFF were first demonstrated by Caldwell for the separation of albumin, lysozyme, hemoglobin, and y-globulin in two different buffer solutions (pH 4.5 and 8.0) [35]. Later, the performance of an El-FFF channel with flexible membranes [36], a channel with rigid membranes [256], or a circular channel [260] for the separation of proteins were described. In these studies, human and bovine serum albumin, y-globulin (bovine), cytochrome C (horse heart), lysozyme (egg white) and soluble ribonucleic acid (t-RNA), as well as denaturated proteins, were successfully separated. 

With several other proteins, such as bovine serum albiunin (Tanford and Roberts, 1952), lysozyme (Tanford and Wagner, 1954), and/3-lacto-globulin (Tanford and Swanson, 1957), pK shifts of the phenolic OH groups of tyrosine residues are observed, but these are of a qualitatively different nature. Thus, the tyrosines of any one of these proteins cannot be readily differentiated into a normal and an abnormal variety, since the spectrophotometric titration data for these proteins are reversible and fall on single smooth curves, in contrast to the situation with RNase. On the other hand, the tyrosine residues of ovalbumin show comparable behavior to the three abnormal tyrosine groups of RNase (Crammer and Neuberger, 1943). About 2 of the total of 9 tyrosine residues appear to titrate normally, but the remainder are not titrated up to pH 12. At pH 13, these anomalous tyrosines become titratable, and this is accompanied by the irreversible denaturation of the ovalbumin molecule. 

The serum albumin of cancer patients also appears to bind less PSP than normal. This is thought (B18) to be due to the occupation of PSP-binding sites by unknown substances occurring in the blood in cancerous states, since after isolation and treatment with alcohol, but not after exhaustive dialysis, the cancer albumin recovers its PSP-binding capacity. However, the possibility that some denaturation occurred during the alcohol treatment cannot be excluded. PSP binding to an abnormal globulin of a myelomatosis serum (H26) is probably a consequence of dehydration and precipitation of the myeloma protein. 

Alexander and Rechnitz [153—155] have used a silver sulphide electrode for the direct determination of changes in total protein level in blood serum as well as albumin globulin ratios, kinetics of protein denaturation and analysis of... 

From the analysis, it was found that proteins were not denatured during the pasteurisation temperature (72°C) for 15 seconds, while all the y-globulin, serum albumin, p-1actoglobulin and d-lacto-albumin was denatured upon heating at 85°C for 30 minutes. This technique was found to be useful for determining the individual protein composition of milk products and assessing the extent of denaturation of individual whey proteins. 

Not all proteins adsorbed in silica are denatured. At least gamma globulins that. are adsorbed on powdered quartz retain their antigenic specificity. Pernis, Clerici, and Ghezzi (273) concluded that this shows that the immunological reactions of silicosis could not be due to antibody production against serum proteins altered, by quartz. However, other types of proteins are definitely denatured and may be the cause of the reactions. . ... 

Boyer, Ballou, and Luck (19). Low concentrationa of fatly add aniona prevented the viscodty increases which otiierwise resulted when the albumin was dissolved in 6 ilf urea. The effect of the fatly add anions increased witii the chain length. Caprylate also prevented the viscodty increase which otbmrise occurred when the albumin was dissolved in 2.5 M guanidine hydrochloride, but it had no stabilizii effect in the presence of 6 M guanidine hydrochloride. Serum y-globulin was not protected from denaturation by the addition of cainylate. 

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