Alpha Amino Acid Synthesis
Alpha amino acid synthesis refers to the process of creating alpha amino acids, which are the building blocks of proteins. This synthesis can occur through various methods, including the Strecker synthesis, Gabriel synthesis, and the biosynthesis pathway in living organisms. These methods involve the combination of specific chemical compounds to form the desired alpha amino acids.
6 Key excerpts on "Alpha Amino Acid Synthesis"
eBook - ePub- J Fisher, J.R.P. Arnold, Julie Fisher, John Arnold(Authors)
- 2020(Publication Date)
- Taylor & Francis(Publisher)
...Section L - Chemical Synthesis Of Biological Molecules L1 Peptide synthesis DOI: 10.1201/9780203079522-46 Key Notes Natural amino acids Compounds referred to as a-amino acids consist of an amino group and a carboxylic acid group, attached to the same carbon. There are 20 naturally occurring amino acids which all have an α-hydrogen, and differ only in the nature of the fourth substituent, referred to as the side chain (R). Nineteen of the 20 naturally occurring amino acids are chiral and all of these have the L-configuration. Functional group protection In synthesizing peptides it is necessary to perform reactions between functional groups in a controlled/directed manner. It is therefore important that amino or carboxylic acid groups, and other types of functional groups present in side chains, are protected, that is made nonfunctional, until required. Coupling reactions The reaction between an amino group and a carboxylic acid group to form an amide or peptide bond is not particularly rapid or efficient. To increase the efficiency of such a reaction additional reagents are involved, referred to as coupling reagents. These generally function by initially binding to the carboxylic acid group and in doing so making the carbonyl of this group more susceptible to the nucleophilic attack of an amine. Solid-phase synthesis The chemical synthesis of all but the smallest peptides is both time- and material-consuming as the growing peptide must be purified after each coupling step. A major step forward in peptide chemical synthesis came with the development of the Merrifield solid-phase technique. This method involves the use of an activated polymer to which the ‘C-terminal’ amino acid is attached, with its amino group available for amide coupling reactions...
- Marco Brito-Arias(Author)
- 2020(Publication Date)
- Bentham Science Publishers(Publisher)
...Aminoacid Biosynthesis Marco Brito-Arias * Unidad Profesional Interdisciplinaria de Biotecnología, Instituto Politécnico Nacional (UPIBI-IPN), Mexico Amino acids are biomolecules composed of an amino group and carboxylic acid as common features and different R substituents attached to a chiral carbon with L-configuration for the biologically active enantiomer in humans except for glycine devoid of chirality (Fig. 129). Biosynthetically, the amino acids are derived from glycolysis, Krebs cycle or the pentose phosphate pathway. Fig. (129)) Tetrahedral projection of amino acids. Based on additional functionalities present in the amino acids, they can be classified in aliphatic, aromatic, polar (hydroxyl and thiol groups), cationic, anionic, and heterocyclic groups (Fig. 130). 1. GLYCINE BIOSYNTHESIS Glycine is the simplest amino acid having hydrogen as R substituent, and therefore not presenting chirality. It is an amino acid with important implications in brain excitatory and inhibitory activities, and in the synthesis of other essential molecules such as muscle supplement creatine, antioxidant glutathione, and as an abundant component in the structural protein collagen. This amino acid is synthesized from amino acids serine, threonine or nutrient choline, and its detailed biosynthesis is described in the following sections (Fig. 131). Fig. (130)) Classification and structure of amino acids. Fig. (131)) General scheme of glycine biosynthetic precursors. Glycine biosynthesis from serine as starting material is carried out by the catalysis of the enzyme serine hydroxyl methyl transferase (SHMT) with participation of tetrahydropteroylglutamate (H 4 PteGlu), which is converted to 5,10-methylene tetrahydropteroylglutamate (5,10-MH 4 PteGlu), and pyridoxal phosphate (B6) as cofactors (Fig. 132). Fig...
eBook - ePub- S. P. Bhutani(Author)
- 2019(Publication Date)
- CRC Press(Publisher)
...Ten of the amino acids require only one or a few enzymatic steps for their biosynthesis from their precursors. The pathways for other amino acids are more complex. The number of enzymes required by cells to synthesise the essential amino acids is large in relation to the number of enzymes required to synthesise the non-essential amino acids. We find the biosynthesis of amino acids involves a common set of reactions. For example, glutamate arises form α-ketoglutaric acid, which is an intermediate in the Kreb’s cycle. The formation of glutamate is a reductive amination taking place in the presence of reducing enzymes. From glutamate we get glutamine easily by simple amidation. The amino group in glutamic acid is transferred to other α-keto acids in the body in another enzymatic reaction. If it reacts with pyruvate (obtained from glycolysis), we get the synthesis of alanine as given below Such a transformation is called transamination because an amino group is transferred from one species to another. A keto acid is converted to the corresponding amino acid and glutamic acid becomes α-ketoglutaric acid which then reacts with ammonia to regenerate glutamic acid. The biosynthesis of amino acids involves a common set of reactions. In addition to transamination reactions, transfer of one-carbon units such as formyl or methyl groups occur frequently. It is not possible here to give details of the reactions for the biosynthesis of all amino acids...
eBook - ePubBiochemistry
An Organic Chemistry Approach
- Michael B. Smith(Author)
- 2020(Publication Date)
- CRC Press(Publisher)
...11 Amino Acids There is an important class of difunctional molecule that is critical to an understanding of biological processes. Amino acids comprise the backbone of peptides, and thereby of enzymes. This chapter will discuss the structure, nomenclature, and characteristics of amino acids. 11.1 Characteristics of Amino Acids An amino acid, as the name implies, has one amine unit (–NR 2) and one carboxylic acid unit (a carboxyl group, COOH). The nomenclature for a generic amino acid is dominated by the carboxyl, so the parent name is “acid” and the NR 2 unit is treated as a substituent. When an amine unit is a substituent the name “amino” is used, so these compounds are amino carboxylic acids, or just amino acids. Amino acids are easily named using IUPAC nomenclature and the carboxylic acid is the parent for each new compound. Two examples are 2-aminopropanoic acid (known as alanine) and 5-amino-3,5-dimethylheptanoic acid. There are a variety of structural variations for amino acids. If the amine unit is attached to C2, the α-carbon of the carboxylic acid chain, the compound is an α-amino acid. If the amine group is on C3, the β-carbon it is a β-amino acid. Similarly, there are γ-amino acids, δ-amino acids, and so on. Due to their biological importance, α-amino acids will be discussed most of the time. The common names of α-amino acids are presented in Table 11.1 in Section 11.2. To distinguish α-amino acids from other amino acids, the term non-α-amino acids is used. 5-Amino-3,5-dimethylheptanoic acid is a non-α-amino acid, for example. Table 11.1 Structures, Names, Three-Letter Code and One-Letter Code of the 20 Essential Amino Acids, Based on the Structure in Figure 11.5 R Name Three-Letter Code One-Letter...
eBook - ePubMedical Biochemistry
Human Metabolism in Health and Disease
- Miriam D. Rosenthal, Robert H. Glew(Authors)
- 2011(Publication Date)
- Wiley(Publisher)
...CHAPTER 20 AMINO ACIDS 20.1 FUNCTIONS OF AMINO ACID METABOLISM Since 20 common amino acids, some with cyclic and branched structures, are utilized for protein synthesis, the synthesis and catabolism of amino acid carbon skeletons can be a complex and daunting subject with a myriad of details. Nonetheless, there are a number of common themes that are of major importance in understanding the overall metabolism of the body. 20.1.1 Synthesis of Amino Acids Some of the 20 common amino acids can be synthesized in the body. The amino-transferase reactions that remove the amino group from most of these amino acids are readily reversible and can therefore be utilized to synthesize amino acids. For example, aspartate aminotransferase can be used to synthesize aspartate from the TCA-cycle intermediate oxaloacetate: Since the glutamate dehydrogenase reaction, too, is reversible, it can be used to incorporate NH 4 + into α-ketoglutarate, generating glutamate. Glutamate, in turn, can donate its amino group for the synthesis of other amino acids: Thus, humans can synthesize a particular amino acid if they can synthesize its corresponding α-ketoacid carbon skeleton. 20.1.1.1 Essential Amino Acids. Certain amino acids, however, cannot be synthesized in the body; these are the essential amino acids and they must be obtained from the diet. The amino acids that are essential in adults are listed in Table 20-1. Two other amino acids, tyrosine and cysteine, can be synthesized from the essential amino acids phenylalanine and methionine, respectively. In addition, although arginine is not an essential amino acid in adults, its rate of synthesis in neonates is not adequate to meet their requirements for optimal growth...
eBook - ePub- Antonio Blanco, Gustavo Blanco(Authors)
- 2017(Publication Date)
- Academic Press(Publisher)
...Other general mechanisms for AA degradation include decarboxylation, which leads to formation of biogenic amines. Transfer of monocarbon groups from AA (methyl, OH-methyl, formyl, and CO 2) are used in various processes of syntheses, catalyzed by specific methyltransferases. Each AA has different metabolic pathways that catabolize them producing energy or different compounds. Thus, phenylalanine is converted to tyrosine, and can produce catecholamines and melanin. Tryptophan produces serotonin, melatonin, and nicotinic acid (a vitamin of B complex). Arginine generates nitric oxide. Glycine participates in biotransformation reactions, cysteine gives taurine, methionine and cysteine give S, which is used in sulfoconjugation. Arginine, glycine, and methionine participate in the synthesis of creatine, glutamate and cysteine in the synthesis of glutathione. Keywords ubiquitin proteasome transamination deamination urea cycle nitrogen balance decarboxylation monocarbon group transfer nitric oxide creatine glutathione Amino acids are commonly used in the body as the building blocks for the synthesis of proteins and a variety of physiologically active nitrogenous compounds (hormones, enzymes, and other functionally important substances). This structural function of amino acids is unique and irreplaceable. They are the main source of nitrogen in the body. While amino acids can be also utilized as fuel, this role is secondary and replaceable by carbohydrates and fats. Unlike carbohydrates and fats, amino acids are not stored in the body. Their amounts depend on amino acid anabolism and catabolism in the body, or nitrogen balance, which is directly related to the rate of synthesis and degradation of proteins. In normal adults, there is a balance between nitrogen intake from the diet and nitrogen elimination through urine and feces. During growth and pregnancy, nitrogen consumption exceeds its excretion...
