Amino compounds environmental sources

Peptide-like compounds raise the further significant issue of chirality control. When all the chiral fragments consist of natural amino acids, the chiral sources are natural amino acids themselves. However, when chiral non-natural amino acids are used as bioisosteres of amino acid residues to construct peptide mimetic compounds, the chirality needs to be constructed as efficiently as possible. Multi-step or low-yielding processes resulting from the necessity to control chirality often lead to the potential risk of large amounts of waste and a high environmental burden. 

Analysis of regulatory networks involved in the adaptation of the metabolism of microorganisms to various environmental conditions, such as starvation, revealed the particular importance of nucleotides and amino acids. These compounds function as signals for starvation, precursors in metabolic pathways, energy sources or are involved in enz3une activity regulation [10,32,33,42,44,110-112]. They are usually determined off -line by HPLC [8,10,32,33,42,44,112], as chromatographic or electrophoretic determinations allow the simultaneous determination of all compounds of... 

Aromatic amines (AAs) and heterocyclic aromatic amines (HAAs) are ubiquitous environmental and dietary contaminants, many of which are carcinogens. Compounds of both classes contain an exocydic amino group, which is a prerequisite for their genotoxicity (Figure 7.1). In this chapter, the sources of exposure, mechanisms of metabolic activation, formation and detection of DNA adducts, and biological effects of AA-DNA and HAA-DNA adducts are highlighted. 

On the microscopic scale, chirality is an important property in life science. All amino acids in proteins are left-handed. On the other hand, all the sugars in the nucleic acids are right-handed. This is in contrast to reagent glass organic chemistry, where usually racemates are produced. However, nature synthesizes completely pure chiral compounds. How chiral substances arrived in living materials is still an open question, it is addressed as chirality problem. Several environmental conditions during synthesis have been considered as the source of chirality, such as [43]... 

Dinitrotoluene (2,4-DNT), listed as a priority pollutant by the United States Environmental Protection Agengr (USEPA) [45], is the major imptirity resulting firom the manufacture of TNT, and is a starting material for the synthesis of toluenediisocyanate, used in the production of polyurethane foam. 2,4-DNT was transformed to 2-amino-4-nitrotoluene, 4-amino-2-nitrotoluene, 2-nitroso-4-nitrotoluene and 4-nitroso-2-nitrotoluene by a mixed culture derived from activated sludge only under anaerobic conditions and with an exogenous carbon source [46]. llie two nitroso compounds were unstable and could be detected between 48 and 72 h of incubation. 

A convenient and clean water-mediated synthesis of a series of 4-amino-2-ar-yl-1,2-dihydro pyrimido[l,2-a]benzimidazoles has been reported using alternative nonconventional energy sources [37]. The products were obtained in shorter times with excellent yields (78-89 %) from the multicomponent reaction of 2-ami-nobenzimidazole, malononitrile/ethylcyanoacetate, and carbonyl compounds (Scheme 8.26). The procedure does not involve the use of aity additional reagent/ catalyst, produces no waste, and represents a green synthetic protocol with high atom economy. The combination of microwave irradiation, ultrasonic irradiation, and aqueous-mediated conditions using multicomponent reactions leads to enhanced reaction rates, higher yields of pure products, easier workup, and sometimes selective conversions. Consequently, this protocol should be welcome in these environmentally aware days. 

All protein concentration methods have sources of error. Colorimetric methods rely on protein standards that may not be representative of the target product protein s response in the assay. AAA and absorbance methods are more direct than colorimetric methods, however, AAA does rely on amino acid standards, and absorbance methods rely on the correspondence of extinction coefficients of model compounds with those of certain amino acid residues within the target protein. Additionally, AAA may suffer from environmental contamination from the laboratory, whereas absorbance methods may suffer from contaminating compounds that absorb light at the wavelength(s) used. Colorimetric results can be influenced by contaminating protein or formulation excipients. 

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