Proteins laboratory synthesis

We ll see in Section 26.7 that this DCC-induced method of amide formation is the key step in the laboratory synthesis of small proteins, or peptides. For instance, when one amino acid with its NH2 rendered unreactive and a second... 

The synthesis of an a-amino acid from an achiral precursor by any of the methods described in the previous section yields a racemic mixture, with equal amounts of S and R enantiomers. To use an amino acid in the laboratory synthesis of a naturally occurring protein, however, the pure S enantiomer must be obtained. 

By using the genetic code, one can take the amino acid sequence of a given protein and come up with a series of trinucleotide codons that would direct that protein s synthesis. Then, thanks to advances in nucleic acid chemistry, the DNA with those codons in the proper sequence can readily be made in a laboratory. In short, one can synthesize an artificial gene. 

Amino Adds, Peptides, and Proteins 26.7 Laboratory Synthesis of Peptides Active Figure 26.4 Mechanism of Amide Formation Using Dicydohexylcarbodiimide (page 1151) Coached Tutorial Problem Reactions Used in Synthesis of Peptides (page 1151)... 

A laboratory synthesis that is patterned after a biological synthesis. For example, the synthesis of amino acids by reductive amination resembles the biosynthesis of glutamic acid. (p. 1164) Proteins that provide all the essential amino acids in about the right proportions for human nutrition. Examples include those in meat, fish, milk, and eggs. Incomplete proteins are severely deficient in one or more of the essential amino acids. Most plant proteins are incomplete, (p. 1160)... 

They supply valuable information on the influence of saccharide size and structure on immuno-genicity. The use of s)uithetic oligosaccharides in the development of glycoconjugate vaccines for human use is, however, a very complex task far beyond a laboratory synthesis of a given oligosaccharide and oligosaccharide-protein conjugate. 

Propose a mechanism for the following reaction, an important step in the laboratory synthesis of proteins ... 

Because modem technology has made possible the laboratory synthesis of proteins, some protein hormones are being synthetically produced for use as medicines. Insulin, thyroid hormones, and growth hormones are some examples. Both natural and synthetic proteins are used in a variety of products— from meat tenderizer to cleaning solutions to health and beauty aids. 

There is an abundant supply of L-enantiomers of most of the coded amino acids. These are made available through large-scale fermentative production in most cases, and also through processing of protein hydrolysates. The early sections of this chapter cover this aspect, However, laboratory synthesis methods are required for the provision of most of the other natural amino acids and for all other amino acids, so the main part of this chapter deals with established syntheses. 

Polymers are found in nature and may also be produced by laboratory synthesis. Important examples of naturally occurring macromolecules, or biopolymers, are proteins, polysaccharides, terpenes, and nucleic acids. General representations of these substances are provided by structures 3-6, respectively, in which the monomeric subunits of an a-amino acid, 3, a pyranose, 4, an isoprene, 5, and a ribonucleotide phosphate, 6, are seen. Synthetic, or man-made, polymers are represented by the myriad plastics, elastomers, and fibers that are commonplace in contemporary society. 

Visneaud, Vincent du (1901-78) American biochemist whose principal contribution was in the field of amino acids. He showed how a series of these important protein constituents were synthesized in the body. He also achieved the laboratory synthesis of thiamine and penicillin, and the hormones oxytocin and vasopressin. He was awarded the 1955 Nobel Prize in chemistry. 

Protein-based therapeutics represent a significant portion of the pharmaceutical market, with over 130 proteins currently approved for clinical use by the FDA for a wide variety of indications (1). Many protein therapeutics are manufactured in bacterial or mammalian cells in large bioreactors, which is in contrast to the laboratory synthesis... 

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