Globulin solution behavior

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). 

Cyclic Voltammetry—5 V/min. Figures la-e present the j-U behavior for the first cycle of copper-2% zinc in phosphated saline and in protein solutions. The corrosion potentials (ia—ic) during the forward scans were between -0.35 to -0.40 V in all cases. Two anodic peaks were observed for all protein solutions at —0.25 to —0.10 V and +0.10 to +0.30 V. The first peak in the supporting electrolyte was also observed, whereas j continued to increase, never reaching a peak up to the reversal potential of +0.5 V. Two main cathodic peaks were observed at —0.30 to —0.45 V and —0.65 to —0.75 V in all cases. A prepeak inflection also occurred at -0.2 to -0.3 V for both the albumin and globulin systems, and a small peak at —1.1 to —1.2 V for most systems. Cathodic currents increase sharply below about —1.5 V. Figures 2a-b represent the surface appearances after the first cycle of polar-... 

Time effects have also been observed for bovine plasma albumin, horse serum albumin and rabbit y-globulin (Beaven and Holiday, 1950). The behavior of bovine plasma albumin was most striking the intensity of the absorption in 0.1 N alkali increased steadily over a period of ca. 3 hours at room temperature the light-scattering properties of the solution, as shown by its apparent absorption on the long-wave side of the absorption band proper, also increased. Of the few proteins which were examined, only lysozyme showed no time effect. With trypsin the change in absorption was small and complete in a few minutes at pH 13, but the solution then became visibly turbid. 

Having proved that fortuitous phenomena and methodical imperfections have been eliminated, we shall try to propose an interpretation of the observed facts. The question of the increment in albumin due to denaturation seems to us to have been satisfactorily answered. However, the question of globulins is different their polarographic wave heights are increased by addition of alkali hydroxide only when the filter paper has remained in the solution serving as eluent. Let us discuss all possibilities concerning the behavior of globulins of diseased subjects, as follows ... 

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