Amino acid biological studies

In order to use fluorinated amino acids to study biological systems, they need to be synthesized and incorporated. Despite the challenges in both steps, there are several methods available. For instance, enantiomerically pure fluorinated amino acids may be prepared by asymmetric synthesis or by stereochemical resolution using enzymatic methods [48], Fluorinated amino acids can be introduced into proteins biosynthetically, or chemically by SPPS. Several reviews that detail the synthesis of enantiomerically pure fluorinated amino acids and incorporation methods into proteins are available [48-51],... 

Laser-microprobc mass spectrometry has an unusually high sensitivity (down to 10 g), is applicable to both inorganic and organic (including biological) samples, has a spatial resolution of about I pm, and produces data at a rapid rate. Some typical applications of laser-microprobe mass spectrometry include determination of Na/K concentration ratios in frog nerve fiber, determination of the calcium distribution in retinas, classification of asbestos and coal mine dusts, determination of fluorine distributions in dental hard tissue, analysis of amino acids, and study of polymer surfaces. ... 

The electron transport protein, cytochrome c, found in the mitochondria of all eukaryotic organisms, provides the best-studied example of homology. The polypeptide chain of cytochrome c from most species contains slightly more than 100 amino acids and has a molecular weight of about 12.5 kD. Amino acid sequencing of cytochrome c from more than 40 different species has revealed that there are 28 positions in the polypeptide chain where the same amino acid residues are always found (Figure 5.27). These invariant residues apparently serve roles crucial to the biological function of this protein, and thus substitutions of other amino acids at these positions cannot be tolerated. 

Continuing our look at the four main classes of biomolecules, we ll focus in this chapter on amino acids, the fundamental building blocks from which the 100,000 or so proteins in our bodies are made. We ll then see how amino acids are incorporated into proteins and the structures of those proteins. Any understanding of biological chemistry would be impossible without this study. 

Biological examples of pericyclic reactions are relatively rare, although one much-studied example occurs during biosynthesis in bacteria of the essential amino acid phenylalanine. Phenylalanine arises from the precursor chorismate,... 

Molecular biology studies have identified a loop containing 20-25 amino acid residues between S5 and S6 (or Ml and M2, Fig. 2) forming the pore. The G(Y/F) G motif located in the pore represents the K+-selectivity signature, which is common to all K+ channels. The external entry to the channel pore and its adjacent residues constitute binding sites for toxins and blockers. The internal vestibule of the pore and the adjacent residues in S5 and S6 contribute to binding sites for compounds such as 4-aminopyiidine and quinidine. The S4-S5 linker lies close to the permeation pathway and is required for... 

The most widely studied interactions between biologically active ligands and organotin(lV) cations relate to the amino acids and their derivatives (N- or S-protected amino acids and peptides), though new data on several of the most commonly occurring amino acids are still being published. This is specially true for aqueous speciation studies. Nice and very detailed reviews were published in this area by Molloy and Nath. ... 

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