Thesis (Ph. D.)--University of Texas at Austin, 2007. / Vita. Includes bibliographical references.

Sanger's dinitrophenyl method has been applied to human γ-globulln. One mole each of aspartic acid and of glutamic acid have been identified as the free α-amino terminal residues. In bovine γ-golubin, free amino groups are located on five different amino acid residues, namely, aspartic acid, glutamic acid, serine, alanine and valine. Each is present in sub-molar quantity indicating that the protein is heterogeneous with respact to N-terminal groups. By a combination of the carboxypeptidase and of the hydrazinolysis methods, one mole each of serine and glycine have been established as the C-terminal amino acids of human γ-globulin. The free carboxyl terminal groups of bovine γ-globulln also have been found to be serine and glycine. Carboxypeptidase erperiments indicate that there is no difference in the release of free amino acid from bovine γ-globulin and human γ-globulin. The C-terminal sequence of these proteins is probably the same. In one chain, serine may be followed by leucine and valine. / Medicine, Faculty of / Biochemistry and Molecular Biology, Department of / Graduate

Attempts have been made to form "in vitro" carcinogen-protein and carcinogen-amino acid complexes by various oxidative processes. Irradiation, chemical oxidation, and a combination of the two have proved unsuccessful. A new method, based upon chromatographic separation, has been developed for the detection of complex formation. Applicability of the procedure was Investigated using a hydrocarbon-amino acid conjugate and"in vivo" formed 3,4-benzpyrene-epidermal protein complex. Complex formation of 3,4-benzpyrene with several purines and nucleic acids was detected in this way. A series of hydrocarbons - both carcinogenic and non - carcinogenic - was substituted for 3,4-benzpyrene, but no correlation between carcinogenic activity and complex formation of the hydrocarbons could be found. In view of the difficulties encountered with "in vitro" complex formation, it was suggested that further investigations be made on the "in vivo" complex. Chromatographic separation of the "in vivo" complex and determination of the fragments after partial hydrolysis looks promising. / Science, Faculty of / Chemistry, Department of / Graduate

The composition, structure and functional properties of proteins are thought to be interrelated but the nature of this relationship is not clearly known. In most studies of the structure-function relationships of proteins, more attention has been focused on the polar residues while the importance of the nonpolarity of the protein molecule has been overlooked. It seems necessary to study the relationships, if any, between hydrophobicity and functional properties which are important in food systems. The purpose of this study has been two-fold. First, establishment of methods for determination of hydrophobicity, and second, to correlate the hydrophobicities with the surfactant properties of proteins. The hydrophobicities calculated so far (Bigelow, 1967; Tanford, 1962; Waugh, 1954) from the amino acid compositions do not appear to correlate with the propensity of protein to form hydrophobic interactions. In an attempt to determine the effective hydrophobicity (the capacity to participate in hydrophobic interactions), column chromatography on substituted Sepharose gels was employed. Oleic acid, aliphatic and aromatic amines were coupled to the CNBr activated Sepharose 4B. However, these gels were not suitable for determination of hydrophobicity. This may be due to the presence of undesirable charges or to the exceedingly strong hydrophobic interactions between the ligand and the proteins. Chromatography on Sephadex G-150 was also employed in the presence of Triton X-100 and the amount of the nonionic detergent bound to the protein was determined. However, lack of repeatability in the determination of the detergent bound to the protein prohibited the application of this method for determination of the effective hydrophobicity. Alkylepoxy derivatives of Sepharose 4B (C4, C6 and C8) were synthesized. Hydrophobic chromatography on the butyl and hexyl derivatives was successful in determination of hydrophobicity. However, since octylepoxy-Sepharose, because of its high hydrophobicity, tightly interacted with the proteins it was found to be impractical for the purpose of measuring hydrophobicity. In an aqueous solvent phase, these adsorbents demonstrate some of the properties of an oil/water interface, including the possibility of denaturing some proteins. Therefore, it is assumed that the proteins were denatured on the octylepoxy-Sepharose gel. The hydrophobic partition method was also employed. Two phase polymer systems of polyethylene glycol/dextran and polyethylene glycol palmitate/dextran were used and the extent of the hydrophobic binding of the proteins to the palmitate group was expressed as the "hydrophobic coefficient" of the proteins. The effective hydrophobicities of proteins determined by hydrophobic chromatography with butyl- and hexylepoxy-Sepharoses and by hydrophobic partition significantly correlated with each other. All of these three methods were found suitable for determination of the effective hydrophobicity. No correlation was found between the effective hydrophobicity and the "average hydrophobicity" (Bigelow, 1967) nor with the molecular weights of the proteins. The interfacial tensions of the 0.2% protein solution/ corn oil interfaces were determined as a parameter of the surfactant properties of proteins. A negative correlation was found to exist between the effective hydrophobicities and the interfacial tensions of the proteins. This result suggests that hydrophobicity is involved in the surfactant properties of proteins. The more hydrophobic the protein, the better the surface active properties, thereby facilitating the emulsifying process. / Land and Food Systems, Faculty of / Unknown

The relationship between the foaming characteristics of proteins and some of their physicochemical properties in bulk solution were examined. The physico-chemical properties which were investigated in relation to foaming were hydrophobicity, charge density, secondary structure, molecular flexibility, dispersibility, viscosity and surface tension, Eleven, model proteins, (ribonuclease, ovomucoid, trypsin, lysozyme, pepsin, ovalbumin, conalbu-min, bovine serum albumin., K-casein, β-lactoglobulin, β-casein) and eight food proteins.(soy, pea, sunflower and canola isolates, pro-pulse, Promine-D, whole casein, acid solubilized gluten) were used. It was found that the average hydrophobicity of proteins could be measured using cis-parinaric acid as a probe of the hydrophobic regions, after the samples had been uncoiled by heating for 1.0. min at 100°C in the presence of 1.5% sodium dodecyl sulphate. Hydrophobicity measured in this way showed a significant linear correlation (r = 0.820, P <0.01 ) with the calculated average hydrophobicity values of Bigelow. Two regression equations.were generated, which accounted for approximately 77% of the variability in the foaming capacities of the proteins; one included hydrophobicity and dispersibility and the other involved hydrophobicity and viscosity as the independent variables. High hydrophobicity and viscosity, and moderate dispersibility were associated with optimum foaming capacity. Although charge density influenced the foaming capacity of proteins its role in determining this property seemed to be a minor one. Highest foaming capacity was exhibited by the most flexible proteins. There was a significant negative relationship (r =-0.726, P<0.01) between foam stability and the reciprocal charge density. This indicated that electrostatic repulsion between protein molecules had an important destabilizing effect on foams. It was demonstrated that hydrophobicity plays an important role in determining the foaming behaviour of protein solutions. Unlike, emulsification, which is dependent on surface hydrophobicity, the hydrophobicity of the uncoiled protein molecule is important for foaming. / Land and Food Systems, Faculty of / Graduate

This thesis describes the results of cert in biochemical investigations on the serum proteins of patients suffering from the protein depleted state, kvashiorkor.

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Thesis (Ph. D.)--University of Nebraska-Lincoln, 2003. / Title from title screen. PDF of dissertation: xix, 393 p. : ill. (some col.). Sites viewed on Feb. 19, 2004. Includes bibliographical references.