<p> A new technique for the systematic identification of metal-protein complexes combining gel chromatography with either neutron activation analysis or radioactive tracer methods has been proposed. The technique has been tested on the copper in serum situation to evaluate the results obtained on a well-known system.</p> <p> It was then applied to manganese in serum, manganese in erythrocytes and copper in erythrocytes. The results indicate that serum contains two manganese-binding proteins, one of low molecular weight and relatively labile in nature, the other of higher molecular weight and incorporating radioactive manganese in vivo at some definite time interval subsequent to the isotope's administration.</p> <p> Manganese in erythrocytes occurs as a porphyrin bound to apoglobin as a manganese analogue of hemoglobin.</p> <p> Copper in erythrocytes appears to exist in two forms - one firmly bound to erythrocuprein, the other more loosely bound to the same protein.</p> / Thesis / Doctor of Philosophy (PhD)

Nature is able to convert chemical energy into mechanical work under modest conditions, i.e., physiological pH and ambient temperature and pressure. One of the most interesting systems is muscle modeled as the "sliding filament" system. The sliding filament system is a combination of a thin actin filament and a thick myosin filament that slide over one another by breaking the "energy-rich" pyrophosphate bond of ATP. The energy from ATP hydrolysis is used for mechanical motion and the energy lost during this process is used to heat our body. In biology, the sliding filament system is taken as a fairly effective model. For engineering systems, the energy lost to heat needs to be reduced to build an efficient energy converter. In our research, we use a phosphate charged protein, casein, and react it with divinyl sulfone (DVS) through a Michael addition reaction to produce a cross-linked gel. The protein gel could be ephosphorylated at standard conditions using bovine phosphatase (bp) and re-phosporylated using casein kinase. When attached to the protein, the negatively charged phosphate groups cause the gel to expand from repulsion. When removed, the protein contracts. Therefore, work is realized without sliding friction, which is the origin of the large energy loss in muscle. FT-IR spectroscopy allows us to follow the two biochemical reactions. We also show a thermodynamic analysis of the work and offer an estimation of the most basic term. / Master of Science

The overall goal was to understand the capabilities of a dairy based meat alternative. This was done in three phases: 1) the production of a dairy protein gel as a base for a dairy based meat alternative, 2) texturization of the dairy protein gel base to produce a nugget like texture, and 3) a consumer test to determine the acceptability of the dairy based nugget compared to meat and meat alternatives on the market. For phase I, a dairy protein gel base was tested to understand the textural attributes. Milk to whey percentages and level of acidification were examined to determine their effects on instrumental textural attributes of the protein gel. The milk to whey percentages and level of acidification that were tested were 5/95, 10/90, and 15/85, and pH 5.70-5.60, 5.15-5.05, and 4.6-4.5; respectively. The texture was objectively measured using a texture analyzer. The results showed that there was an increase in the hardness, gumminess and chewiness which was associated with an increase of the milk to whey ratio. Also a firmer dairy protein gel was produced using a low pH. A milk to whey percentage of 15/85 and a pH of 4.6-4.5 produced the highest overall instrumental textural attributes, specifically . For phase II, the dairy protein gel composed of a milk to whey ratio of 15/85 and pH of 4.6 was evaluated in the formulation of a dairy based nugget. The grinding of the dairy protein gel was used to determine if different size grinding plates and the presence of a gum can influence the textural attributes of the dairy protein gel. The dairy protein gel base was evaluated by a trained sensory panel to compare to the results of the objective texture analyzer. The dairy protein gel was processed using a meat grinder with a grind size of 3 mm, 6 mm and a blend of 4 parts 6 mm grinded and 1 part 3 mm. The increase in the grind size produced an increased instrumental hardness, springiness, cohesiveness, chewiness and gumminess. The usage of gum in the dairy protein gel system produced a higher instrumental adhesiveness. The sensory results showed that an increase in the grind size increased the sensory attributes; hardness, cohesiveness, chewiness and adhesiveness. The use of gum in the system had no influence on the sensory textural attributes. Both the texture analyzer and trained sensory testing showed a similar trend for the texture attributes. No correlation between the texture analyzer and sensory was found. This was a surprise because literature indicates there are significant correlations between instrumental textural attributes and sensory texture attributes. The lack of correlation may be explained by the variability of the panelists (P-value<0.05) for each sample. For phase III, an acceptability test was performed on untrained consumers of chicken nuggets to determine if the dairy based meat alternative was acceptable compared to meat nuggets and meat alternatives on the market. Texture, flavor, and appearance were evaluated by a consumer panel. The consumers evaluated the dairy based meat alternative and concluded that the appearance, texture and flavor needed improvement. From this research, it was concluded that a dairy based meat alternative can be created to imitate meat and meat alternative textures. By understanding the processing conditions to produce the dairy protein gel base and grinding of the product, an acceptable meat alternative can be produced. Dairy based meat alternative texture attributes were produced from a milk to whey percentage of 15/85 and a pH of 4.6, and a large grind plate of 6 mm with the use of methylcellulose.

Channel catfish raising is an important aquaculture in the United States. Mississippi ranks No.1 in catfish production for continuous 4 years. However, catfish fillet processing generates huge amount of by-products, including heads, bone frames, visceras and skins, which contain significant amount of proteins. Removing and utilization of proteins from the by-product would add value to the catfish industry. Collagen was extracted from catfish skin by: (1) acid extraction; (2) homogenization-aided; and (3) pepsin-aided extraction methods. Kinetic analysis of the extraction was performed. SDS-PAGE was performed to analysis the composition of proteins in collagens extracted under different conditions. Collages extracted by three methods was characterized by solubility test, zeta potential, circular dichroism and gel strength. Protein recovery rate from minced skin extracted with pH 2.4 HCl containing 23.6 KU/g pepsin was the highest (64.19%). Papain, ficin, bromelain, neutrase, alcalase, protamex, novo-pro D and thermolysin were used for the hydrolysis of the mixture of heads and frames. Proteolytic activities of these proteases were examined using AzocollTM as a standard substrate. Degree of hydrolysis (DH) of hydrolysates and enzyme reaction kinetics were investigated. Results indicated that thermolysin had the highest activity (82.9×107 AzU/g) at 50 °C when using AzocollTM as the substrate. Ficin (80 AzU/g) was the most efficient in hydrolyzing the proteins in the ground catfish by-product (DH reaching 71.88%) in 120 min at 30°C among all the enzymes. Thermolysin could be used for industries to hydrolyze protein by-products in terms of hydrolysis efficiency and economy. The hydrolysis curves fit the Peleg model very well, all with R2 higher than 0.91. Myofibrillar proteins were extracted from the mixture of heads and frames with different pH conditions, and made into protein gels. Transglutaminase (TGase) was incorporated to improve the gel structure. Solubility and secondary structures of extracted myofibrillar proteins were studied. Gelling properties of the protein sol were studied by dynamic rheological measurement. Physicochemical, textural and thermal properties of protein gels treated with TGase were investigated. Protein pattern changes of TGase treated protein gel was studied by SDS-PAGE. Results indicated that alpha-helicity of myofibrillar proteins decreased with extraction pH over 9. Storage modulus (G’) of protein sol decreased as the increase of extraction pH. Rheological measurement of TGase treated protein sol showed that excessive TGase could weaken the gel structure. This study provides systematic information for the catfish fillet processing industry to utilize the by-products.

Conselho Nacional de Desenvolvimento Científico e Tecnológico / Barium Titanate (BaTiO3 BT) based Ceramic materials have a wide industrial application as Multilayer Ceramic Capacitors (MLCCs) mainly due to its high dielectric constant and good capacitance stability with the temperature change, however this material also presents some limitations, for example, oxidation of low cost electrodes. Several ways of BT modifications have been proposed in Literature, as example, the use of different synthesis methods and the doping with different ions. Therefore, the present work had as objectives the synthesis, sintering and electrical characterization of the BaTiO3 and Ba0.77Ca0.23TiO3 (Barium Calcium Titanate) ceramics. The Sol Gel Proteic method was used to powder synthesis, in this method, coconut water is employed as polymeric agent instead of the conventional alcoxide precursors. The characterization was done using the differential thermal analysis, thermogravimetry, x-ray powder diffraction, scanning electron microscopy and impedance spectroscopy techniques. Both, the calcined powders at 1100 °C and the sintered ceramics at 1350 °C presented single crystalline phase, with good microstructural homogeneity and relative density higher than 90%. The sintered ceramics presented a dielectric constant value at room temperature of 1200 (BT) and 680 (BCT), and dielectric loss of 4,8% (BT) and 1,8% (BCT). Besides, the BCT ceramics presented a Curie temperature on average 14 °C above that observed in Literature. Finally, the activation energies of the conductive process of the grain an grain boundary regions were evaluated following two distinct methods using: i) the Brick-layer model; and ii) the average relaxation frequency of each ceramic region, grain and grain boundary. The obtained values by the two methods are in accordance with them and suggest that the dominant conduction mechanism occurs by oxygen vacancy diffusion created still during the sintering process. / Materiais cerâmicos a base de titanato de bário (BaTiO3 BT Barium Titanate ) possuem uma larga aplicação industrial como Capacitores Cerâmicos Multicamadas (MLCCs Multi layers ceramic capacitors ) devido, principalmente, a sua alta constante dielétrica e boa estabilidade da capacitância com a variação da temperatura, porém esse material apresenta também algumas limitações, como por exemplo, a oxidação de eletrodos de baixo custo. Diversas modificações no BT têm sido sugeridas na literatura, como a utilização de diferentes métodos de síntese e a dopagem com diferentes íons. Dessa forma, o presente trabalho objetivou a síntese, a sinterização e a caracterização elétrica de cerâmicas de BaTiO3 e Ba0.77Ca0.23TiO3 (Titanato de Bário e Cálcio BCT Barium Calcium Titanate ). Para a síntese dos pós foi utilizado o método sol-gel proteico, neste método, a água de coco é utilizada como agente polimérico, ao invés dos alcóxidos convencionais. Para a caracterização das amostras foram utilizadas as técnicas de análise térmica diferencial, termogravimetria, difração de raios X, microscopia eletrônica de varredura e espectroscopia de impedância. Os pós calcinados a 1100°C bem como as cerâmicas sinterizadas a 1350°C e apresentaram fase cristalina única, com boa homogeneidade microestrutural e densidade relativa superior a 90%. O valor da constante dielétrica à temperatura ambiente foi de 1200 para o BT e 680 para o BCT com perda dielétrica de 4,8% e 1,8%, respectivamente. Além disso, as cerâmicas de BCT apresentaram uma temperatura de Curie em média 14 °C acima dos valores observados na Literatura. Por ultimo, as energias de ativação dos processos condutivos nas regiões de grão e de contorno de grão foram obtidas seguindo dois procedimentos distintos: i) utilizando o modelo de brick-layer; e ii) utilizando a frequência de relaxação média de cada região da cerâmica, grão e contorno de grão. Os valores obtidos pelos dois métodos concordaram entre si e sugerem que o mecanismo de condução dominante ocorre por vacâncias de O2- formadas ainda durante o processo de sinterização.