Wael Abdelmoez

Production of Amino and Organic Acids from Protein Using Sub-Critical Water Technology

Abstract This work presents the hydrolysis of a water-soluble protein, bovine serum albumin (BSA), for the production of both amino and organic acids under the sub-critical water condition in the temperature range of 200–300°C. The products of the reaction were a water-insoluble solid phase, an aqueous phase, and an insignificant gas phase which was neglected in this study. Results have shown that BSA passes through an aggregation step, followed by a gel formation process which results in the formation of insoluble solid aggregates. Then, such formed solids unfolded with releasing polypeptides as an intermediate product then finally hydrolyzed to produce low molecular mass products such as amino and organic acids. It was found that there were insignificant amino acids produced in the temperature ranges of 200–225°C within 2 min and 275–300°C within 0.5 min. However, by extending the reaction time, the protein transferred to both amino and organic acids.

Synthesis of New Polymer-Bound Adenine Nucleotides Using Starburst PAMAM Dendrimers

Two types of new polymer‐bound adenine nucleotides were synthesized by coupling adenine nucleotides (ATP and ADP) with starburst polyamidoamine (PAMAM) dendrimers. The first type was obtained by coupling native adenine nucleotides directly with a carboxy‐terminated PAMAM dendrimer. In the second type, the nucleotides were modified by introducing a spacer arm containing a carboxylic end group ( N6‐R‐ATP and N6‐R‐ADP) and coupled with an amine‐terminated PAMAM dendrimer. Both types of the dendrimers were coupled with native or the modified nucleotides using the well‐known carbodiimide activation technique. The optimum coupling pH and temperature were 4 and 30 °C, respectively, for preparing the carboxy‐terminated PAMAM‐bound ATP or ADP, and were 9 and 50 °C, respectively, for preparing the amine‐terminated PAMAM‐bound N6‐R‐ATP or N6‐R‐ADP. The ATP or ADP contents in the synthesized polymers were found to be 4 mol of ATP or of ADP/mol of carboxy‐terminated PAMAM‐bound ATP or ADP and 25 mol of ATP or of ADP/mol of amine‐terminated PAMAM‐bound N6‐R‐ATP or N6‐R‐ADP. The coenzymatic activities relative to the native ATP of the carboxy‐terminated PAMAM‐bound ATP against glucokinase and hexokinase were 16 and 7%, respectively, and those of the amine‐terminated PAMAM‐bound N6‐R‐ATP 2 and 1%, respectively. The coenzymatic activities relative to the native ADP of the carboxy‐terminated PAMAM‐bound ADP and the amine‐terminated PAMAM‐bound N6‐R‐ADP against acetate kinase were 24 and 3.5%, respectively.

Pathways of Amino Acid Transformation and Decomposition in Saturated Subcritical Water Conditions

The reactions of amino acids under subcritical water conditions were investigated. All reactions were carried out under a pressure value corresponds to the saturated vapor pressure of water at the employed reaction temperature (hereafter called the saturated subcritical water condition). The reaction temperatures were in the range of 503-563 K. As reactants, seventeen different amino acids were investigated including, glycine, alanine, valine, leucine, isoleucine, methionine, phenylalanine, tyrosine, serine, threonine, cysteine, proline, lysine, histidine, arginine, aspartic, and glutamic. The obtained data revealed that the major decomposition pathway were the deamination and decarboxylation. It was found that glycine, alanine, valine, and proline were synthesized as intermediate decomposition products of other amino acids. Glutamic acid is the only amino acid that decomposed through lactamization process to pyroglutamic acid. Based on the experimental data a general decomposition pathway of all tested amino acids was developed by considering that the decomposition reactions extended to produce final decomposition products, carbon monoxide, water, and ammonia.

Kinetics and mechanism of the synthesis of a novel protein-based plastic using subcritical water.

We investigated the intermolecular mechanism and kinetics of the synthesis of a novel biodegradable protein‐based plastic from bovine serum albumin under subcritical water conditions using batch reactors. The reaction mechanism could be viewed as a chain reaction stabilized by the formation of intermolecular disulfide bonds. The kinetic analysis was based on non‐steady‐state kinetics using a theoretical model developed in one of our previous works. The activation energy and pre‐exponential factor were found to be 7.2 kJ/mol and 0.9 s−1, respectively. These low values signify that the reaction is relatively temperature‐insensitive with some diffusion limitation.