Films globulin

Factor Xll-deficient plasma, like normal plasma, did deposit matter onto the gamma-globulin films but was unable to removfe it (Table II,... 

Neither the presence of heparin nor that of EDTA in solution inhibited desorption by intact plasma (Table III). On the other hand, when a preformed globulin film was first exposed to protamine sulfate, though this exposure affected film thickness very little (Table IV), normal intact plasma could no longer remove matter but only deposit it (Table IV, Exp. No. 2). 

The matter deposited by normal plasma onto globulin films that had (Table IV, Exp. No. 1) or had not been pre-exposed to protamine sulfate (not listed) did not adsorb matter out of anti-human fibrinogen serum and therefore was probably not fibrinogen. 

When exposure of a globulin film to protamine sulfate was followed by renewed exposure to globulin, more of the latter was deposited after which normal intact plasma would deposit more matter but remove little (Table IV, Exp. No. 4 and 5). If, however, exposure of the globulin film to protamine sulfate was followed by exposure to heparin (Exp. No. 6 and 7) again causing minimal changes in film thickness, the resulting surface... 

Figure 3. Amount (degrees, ellipsom-eter readings) adsorbed out of antialbumin serum, in % of total adsorbed out of it and out of anti-7s gammaglobulin serum (curve G) or anti-fibrinogen serum (curve F), plotted against % of albumin (wt/wt) in 7s gammaglobulin (curve G) or fibrinogen solution (curve F). Intercept of curve G with Y axis shows some matter was adsorbed out of anti-albumin serum onto albumin-free globulin film.

In recent, unpublished experiments, the protein that platelets were suspended in appeared to determine to which film of protein they would adhere. For example, platelets suspended in albumin may adhere less to fibrinogen than to gamma-globulin films on glass or anodized tantalum. 

Discontinuities are seen in the relationship between increase in film pressure, An, and lipid composition following the injection of globulin under monolayers of lecithin-dihydro-ceramide lactoside and lecithin-cholesterol mixtures. The breaks occur at 80 mole % C 16-dihydrocaramide lactoside and 50 mole % cholesterol. Between 0 and 80 mole % lactoside and between 0 and 50 mole % cholesterol the mixed films behave as pure lecithin. Two possible explanations are the formation of complexes, having molar ratios of lecithin-lactoside 1 to 4 and lecithin-cholesterol 1 to 1 and/or the effect of monolayer configurations (surface micelles). In this model, lecithin is at the periphery of the surface micelle and shields the other lipid from interaction with globulin. 

Figure 2. Effect of lipid composition on surface pressure of films in interaction with rabbit y-globulin at 1 digram/ml.

Film penetration studies show unequivocally that lecithin-cholesterol mixtures containing from 0 to 50 mole % cholesterol and lecithin—lactoside mixtures containing from 0 to 80 mole % Ci6-dihydroceramide lactoside have the same effect as pure lecithin. This suggests the presence of a lipid complex in which lecithin prevents the interaction of the cholesterol or ceramide lactoside with globulin. Over these ranges of composition the lipid film would consist of a mixture of the lecithin-cholesterol or the lecithin-lactoside complex with excess lecithin. One may picture two models in which the protein contact is restricted to molecules of lecithin. In one, individual polar groups of the protein interact with the excess lecithin molecules as well as with the lecithin portions of the complex. In the other model, the protein as a whole interacts with the lecithin sites of polymeric lipid structures. The latter, which could be referred to as surface micelles (I), are visualized also through the term "mono-... 

A model that is consistent with these observations of the action of trypsin and phospholipase A and with the discontinuities in the All-composition curves (Figures 2 and 3) is one in which the lipid monolayer is not a continuous palisade of uniformly oriented lipid molecules but rather an assembly of surface micelles. In this model, proposed by Colacicco (4, 5), the protein first comes into contact with the lipid molecules at the periphery of the surface micelles and then inserts itself as a unit between them. This is the basis for the generalized nonspecific interaction between lipids and proteins which results in increase of surface pressure. One may thus explain the identical All values obtained with films of lecithin and 80 mole % lactoside by picturing the lecithin molecules outside and the lactoside molecules inside the surface micelles. In this model lecithin prevents the bound lactoside from interacting nonspecifically with globulin and produces the same increase in pressure as with a film of pure lecithin. In the mixed micelle the lactose moiety of the lactoside protrudes into the aqueous subphase. Contact of the protein with these or other nonperipheral regions of the surface micelle would not increase the surface pressure. 

Fibrinogen, silk fibroin, and 7-globulin pK s for part of Tyr s high also titrations of insoluble films Schauenstein (1955)... 

E699 Green, R.J., Day, B.S. and Powers, D.M. (1991). Multilayer-film bromcresol green method for albumin measurement significantly inaccurate when albumin/ globulin ratio < 0.8 (Response to a letter). Clin. Chem. 37, 767-768. 

Equilibrium spreading pressures (iTe) of proteins and LMWE at the air-water interface as a function of pH and temperature were also studied (Patino and Martin, 1994 Nino et al., 2001,2005). The equilibrium spreading pressure is a measure of the surface activity of spread films at equilibrium. The magnitude of He was dependent on the emulsifier and on the aqueous phase composition. Eor example, the minimum for 7 and 11S soy globulin fractions at pH 5 as compared with Tig on aqueous solutions at pH different to pi can be explained by the fact that the protein is more difficult to convert into a monolayer at its isoelectric point. This behavior is not observed for globular milk proteins (like WPl). 

Mitra and Lundblad (1978) studied the thin channel ultra-filtration of immune serum globulin (ISG) and human servan albvimin (HSA). Data were interpreted using the film theory relationship of ... 

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