Proteins and toxicity

Zhou, S., Chan, E., Duan, W. et al. (2005) Drug bioactivation, covalent binding to target proteins and toxicity relevance. Drug Metabolism Reviews, 1, 41-213. 

Freir DB, Nicoll AJ, Klyubin I, Panico S, Me Donald JM, Risse E et al (2011) Interaction between prion protein and toxic amyloid p assemblies can be therapeutically targeted at multiple sites. Nat Commun 2 336... 

Vijayalakshmi, A., Arockiasamy, D. L., Nagendran, A., and Mohan, D. 2008. Separation of proteins and toxic heavy metal ions from aqueous solution by CA/PC blend ultrafiltration membranes. Separation and Purification Technology 62 32-38. 

In general, nonconventional protein foods must be competitive with conventional plant and animal protein sources on the bases of cost delivered to the consumer, nutritional value to humans or animals, functional value in foods, sensory quality, and social and cultural acceptability. Also, requirements of regulatory agencies in different countries for freedom from toxins or toxic residues in single-cell protein products, toxic glycosides in leaf protein products, pathogenic microorganisms, heavy metals and toxins in fish protein concentrates, or inhibitory or toxic peptide components in synthetic peptides must be met before new nonconventional food or feed protein products can be marketed. 

Proteins and Meals. Nutritional properties of the oilseed protein meals and their derived products are deterrnined by the amino acid compositions, content of biologically active proteins, and various nonprotein constituents found in the defatted meals. Phytic acid (3), present as salts in all four meals, is beheved to interfere with dietary absorption of minerals such as 2inc, calcium, and iron (67) (see Food toxicants, naturally occurring Mineral nutrients). ... 

Purification. Hemoglobin is provided by the red blood ceU in highly purified form. However, the red ceU contains many enzymes and other proteins, and red ceU membranes contain many components that could potentially cause toxicity problems. Furthermore, plasma proteins and other components could cause toxic reactions in recipients of hemoglobin preparations. The chemical modification reactions discussed herein are not specific for hemoglobin and may modify other proteins as well. Indeed, multifimctional reagents could actually couple hemoglobin to nonhemoglobin proteins. 

Several chemical compounds may cause inflammation or constriction of the blood vessel wall (vasoconstriction). Ergot alkaloids at high doses cause constriction and thickening of the vessel wall. Allylamine may also induce constriction of coronary arteries, thickening of their smooth muscle walls, and a disease state that corresponds to coronary heart disease. The culprit is a toxic reactive metabolite of allylamine, acrolein, that binds covalently to nucleophilic groups of proteins and nucleic acids in the cardiac myocytes. 

Cadmium is extremely toxic and accumulates in humans mainly in the kidneys and liver prolonged intake, even of very small amounts, leads to dysfunction of the kidneys. It acts by binding to the —SH group of cysteine residues in proteins and so inhibits SH enzymes. It can also inhibit the action of zinc enzymes by displacing the zinc. 

Currently, five different molecular classes of mdr efflux pumps are known [5], While pumps of the the ATP-binding cassette (ABC) transporter superfamily are driven by ATP hydrolysis, the other four superfamilies called resistance-nodulation-division (RND), major facilitator superfamily (MFS), multidrug and toxic compound extrusion (MATE), and small multidrag resistance transporter (SMR) are driven by the proton-motive force across the cytoplasmic membrane. Usually a single pump protein is located within the cytoplasmic membrane. However, the RND-type pumps which are restricted to Gram-negative bacteria consist of two additional components, a periplasmic membrane fusion protein (MFP) which connects the efflux pump to an outer... 

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