Bases amino acids

Amphiprotic (Section 26.1) Capable of acting either as an acid or as a base. Amino acids are amphiprotic. 

This type of yvn-seleclivc aldol addition has been applied in the synthesis of the unusual L-threonine based amino acid, (2,S, 3/ ,6F)-3-hydroxy-4-methyl-2-methylamino-6-octenoic acid, of cyclosporine104, of the cyclic hexapeptide echinocandin105, and of the antibiotic ionomycin97. 

Chance DH, Adam BW, Smith SJ, Alexander JR, Hillman SL, Hannon WH (1999) Validation of accuracy-based amino acid reference materials in dried-blood spots by tandem mass spectrometry for newborn screening assays. Clin Chem 45 1269-1277. 

Sayano, K. Kono, H. Gromiha, M. M. Sarai, A., Multicanonical Monte Carlo calculation of the free-energy map of the base-amino acid interaction, J. Comput. Chem. 2000, 21, 954-962... 

Some simple substrates (feedback) Metabolic products, e.g. glutamine, nucleotide bases, amino acids, and upon gene expression... 

Figure 1 (a) Structures of common sulfur-based amino acids and tripeptides, (b) Structures of nucleic acid... 

Rouse JG, Yang J, Barron AR, Monteiro-Riviere NA (2006) Fullerene-based amino acid nanoparticle interactions with human epidermal keratinocytes. Toxicol. In Vitro 20 1313-1320. 

Amphoteric. Compounds having the capability of acting as an acid or a base. Amino acids are amphoteric—their molecules contain both an acid group (-COOH) and a basic group (-NH2). 

Demange P, Bateman A, MacLeod JK, Dell A, Abdallah MA (1990) Bacterial Side-rophores Unusual 3,4,5,6-Tetrahydropyrimidine-Based Amino Acids in Pyoverdins from Pseudomonas fluorescens. Tetrahedron Lett 31 7611... 

Table 6 Schiff Base Amino Acid Coordination Compounds whose Structures are Known from X-ray Crystallographic Studies...

Figure 2.3 Proposed model for the semisynthetic RNAse-S complex incorporating a pyridoxal-based amino acid residue. The S-peptide fragment is highlighted, illustrating the location ofpyridoxal (Palg) and the general acid-base pair. (Reprinted with permission from Ref. 28.

An aqueous solution containing ammonia, hydrogen cyanide, and simple organic compounds such as formaldehyde and cyanoethine, in contact with rocks, constituted substrates and the environment for the prebiotic synthesis of more complex organic molecules purine and pyrimidine bases, amino acids, and sugars -the building blocks of all the organisms. 

Oxazole and thiazole-based amino acids were shown to undergo novel cyclooligomerisations in the presence of pentafluorophenyl diphenyl phosphinate (FDPP) producing the natural hexapeptide dendroamide A <02H(58)521>. 

A library of cyclic peptides was obtained by the cyclooligomerization of mixtures of azole-based amino acids. This synthetic approach was applied to the synthesis of bistratamide H and didmolamide A, cyclic peptides containing oxazole rings <07OBC1541>. Other cyclic scaffolds based on oxazole peptides were published <07EJO1779 07T9862 07NAR3272>. 

Knowledge of the three-dimensional structure of ascorbate oxidase and of amino-acid sequences of all members of the blue oxidases made it possible to carry out a structurally based amino-acid sequence alignment 101) involving N. crassa laccase, cucumber ascorbate oxidase, and human ceruloplasmin. The structural basis of this alignment was... 

Structurally Based Amino-Acid Sequence Alignment of Fungal Laccases, Ascorbate Oxidases, and Related Proteins "... 

A structurally based amino-acid sequence alignment strongly suggests a three-domain structure for laccase, closely related to ascorbate oxidase, and a six-domain structure for ceruloplasmin. These domains demonstrate homology with the small blue copper proteins. The relationship suggests that laccase, like ascorbate oxidase, has a mononuclear blue copper in domain 3 and a trinuclear copper between domain 1 and domain 3, and ceruloplasmin has mononuclear copper ions in domains 2, 4, and 6 and a trinuclear copper between domain 1 and domain 6. 

Figure 2.6. Biosyuthesis of RNA Bases. Amino acids are building blocks for the biosynthesis of purines and pyrimidines.

Figure 3, opposite page. Structure-based amino acid alignment of coronin 7 with AIP-1, a protein containing two WD domains. Each domain forms a seven-bladed p propeller." ... 

Syntheses of optically active silicon-containing amino acids, particularly, of sila-proline-, imidazolidine-, and oxazolidine-based amino acids 03MI86. 

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