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Biophysical and Biochemical Characterization of Peptide, Protein, and Bioconjugate Products
Published in Sandeep Nema, John D. Ludwig, Parenteral Medications, 2019
Tapan K. Das, James A. Carroll
Simply put, the primary structure of a protein consists of its amino acid sequence. For recombinant proteins, the amino acid sequence can be predicted from the cDNA used in its production. This basic attribute of a protein determines the entirety of its biophysical and biochemical properties under given conditions. The amino acid sequence of a protein determines its ability to fold properly and thus determines its ability to maintain its function. Therefore, a change in the primary structure, depending on its location, may have a range of effects on a protein’s activity, from no effect to a very large impact. The amino acid sequence can also impact the chemical and physical stability of a protein, even when there is no measurable impact on activity. Thus, confirming the amino acid sequence of a protein is fundamental to understanding its overall structure and properties.
Separation and Purification in Biotechnology
Published in Shintaro Furusaki, John Garside, L.S. Fan, The Expanding World of Chemical Engineering, 2019
Proteins and polypeptides are the most important of the various biochemical products. A scheme for the synthesis of proteins in vivo is shown in Figure 14.2. A gene encoding a protein in DNA is transcribed to mRNA by RNA polymerase. Then, according to the information about the amino acid sequence (the primary structure) written in mRNA the protein is synthesized. The characteristics of the amino acid sequence determine partial conformations such as a-helices and (sheets (the secondary structure) and a specific steric structure of the protein (the tertiary structure). Sometimes several subunits aggregate to form an oligomeric protein (the quaternary structure). The specific biological activity of the protein depends on the steric structure. Since tens or even hundreds of the twenty kinds of amino acids make peptide bonds to construct protein molecules, an enormous variety of proteins with different characteristics can exist.
Biomolecules and Tissue Properties
Published in Joseph W. Freeman, Debabrata Banerjee, Building Tissues, 2018
Joseph W. Freeman, Debabrata Banerjee
Proteins have multiple layers of structure; they are primary, secondary, tertiary, and quaternary structures. The primary structure is the amino acid sequence of the polypeptide. It is the list of amino acids in the protein in order. The secondary structure is the three-dimensional shape that results after the folding of a chain or part of a chain. It is regular, repeated patterns of folding of the protein backbone. The folding is the result of the interactions between the amino acids in the primary structure. The forces that drive protein folding are hydrophobicity and hydrophilicity. To hide hydrophobic side chains, molecules fold in different ways creating commonly used motifs (the two most common folding patterns are the alpha helix and the beta sheet). Proteins fold in a way that packs hydrophobic side chains into the interior of the molecule. This makes a hydrophilic shell and hydrophobic core (Figures 3.3 and 3.4).
Gene Editing: A View Through the Prism of Inherited Metabolic Disorders
Published in The New Bioethics, 2018
Living organisms can be viewed as complex biological systems. Thousands of different chemical reactions occur every second in every cell of our bodies, for example generating energy that powers muscle contraction or neuronal synaptic firing, synthesizing new proteins to permit growth, or degrading or recycling waste-products. ‘Metabolism’ is the sum total of these chemical reactions. Virtually every chemical reaction is catalysed by a unique enzyme, a protein that recognizes specific substrates and facilitates the conversion to the product of the chemical reaction. The protein that forms a specific enzyme is itself encoded by a unique gene, whose nucleotide base sequence provides the ‘blueprint’ for the amino acid sequence of the protein. As Zwart comments (2018), ‘The genome is the primordial layer from where multiple circuits and complicated networks of molecular messages pervade living organisms’.