Amino acid-based functional

Kumar et al. used amino acid-based functional IL [Bz-his(n-propyl)2-OMe+Br ] or [BHP-OMe][Br] 39 for dia-stereoselective S5mthesis of dihydrothiophenes 40 41 in good yield. The methodology involved a three-component one-pot reaction of 2-arylidenemalononitrile, 1,3-thiazolidinedione, and aliphatic/aromatic amines in the presence of [BHPOMe][Br] and water at 70 °C in 14 h. The investigators also screened the effectiveness of... 

Uchegbu and coworkers have studied the complexation and delivery of DNA using a unique poly(amino acid)-based polymer vesicle. A polymer of either poly (L-lysine) or poly(L-omithine) was functionalized with methoxy-poly(ethylene glycol) (mPEG) and hydrophobic palmitic acid chains to synthesize an amphiphilic triblock of either mPEG-6-poly(L-lysine)-6-palmitoyl or mPEG-Z>-poly(L-omithine)-6-palmitoyl. Vesicles formed from these polymers were complexed with DNA and showed improved transfection in vitro over poly(amino acid) complexed with DNA or DNA alone [82]. 

Aside from the cysteine motif, conserved regions in the proteins encoded by WHnl.O and WHul.6 are likely to reflect functional roles. Based on the rules of Von Heijne (70), the N-terminal 16 amino acids may function as a signal peptide for secretion. Recombinant WHbl.O and WHt/1.6 proteins are secreted into the medium of infected insect cells (43)... 

Ribonuclease is an enzyme with 124 amino acids. Its function is to cleave ribonucleic acid (RNA) into small fragments. A solution containing pure protein, with no other ions present except H+ and OH- derived from the protein and water, is said to be isoionic. From this point near pH 9.6 in the graph, the protein can be titrated with acid or base. Of the 124 amino acids, 16 can be protonated by acid and 20 can lose protons to added base. From the shape of the titration curve, it is possible to deduce the approximate pATa for each titratable group.1-2 This information provides insight into the environment of that amino acid in the protein. In ribonuclease, three tyrosine residues have "normal values of pATa(=10) (Table 10-1) and three others have pA a >12. The interpretation is that three tyrosine groups are accessible to OH, and three are buried inside the protein where they cannot be easily titrated. The solid line in the illustration is calculated from pA"a values for all titratable groups. 

Figure 9.31 Six categories of amino acids based on their different functional groups.

A compelling case can be made for replacing empirically-derived scales of amino acid properties with parameters either measured directly (e.g., chemical shift data or infrared spectra) or calculated from basic principles. The goal would be to develop all-electronic expressions for the physico-chemical properties of amino acids based on computational methods that include QM calculations. A start in this direction was provided by the successful description of steric effects in terms of polarizability and hydrophUicity as a function of electron density (32). Application of more sophisticated computational approaches wiU speed progress toward this objective. 

Amino acids and GABA have been functionalized to give amino-acid based... 

Figure 4.2 Structures of main prosthetic groups that contribute significantly to the UV-visible spectroscopy of proteins. Prosthetic groups are non amino acid-based moieties that are covalently attached to the proteins concerned and play an integral part of the structure and function of proteins to which they are covalently attached.

Tsang, K.Y.,Diaz, H.,Graciani,N. andKelly,J.W. (1994) Hydrophobic cluster formation is necessary for dibenzofuran-based amino acids to function as P-sheet nucleators. J. Am. Chem. Soc. 116 3988-4005. 

Amino acids are extremely important to living systems because they form the bases of the many proteins necessary for life. There are 20 common amino acids that function as protein building blocks (Table 3.6.2). There are at least 31 additional amino acids not commonly part of natural proteins among these are some hormones and neurotransmitters (Garrett and Grisham, 1999). 

Poly(amino acid)-based nanoparticles with different surface PEGylation were prepared. a,b-Poly(A-2-hydroxyethyl)-D,L-aspartamide (PHEAS) and PEG-modified PHEA (PHEAS-PEG) were functionalized with a methacrylate group and then polymerized by UV irradiation in inverse microemulsion. The resulting nanoparticles had a size of around 250 nm in diameter by TEM. The fluorescein-loaded PHEA-based nanoparticles were prepared in the presence of fluorescein sodium salts, and examined for cellular uptake using macrophage cells. ... 

A series of biodegradable functional amino acid-based PEAs were designed and synthesized by the solution copolycondensation of antino add (L-phenylalanine and DL-2-allylglycine)- and dicarboxylic acid-based monomers... 

Box 1.1). Each protein, when newly synthesized, starts as a linear chain of amino acids. Based on the properties of the amino acids in the chain, it then bends on itself forming a compact, functional structure with a size, shape, and set of chemical properties that enable it to perform its function. 

Mallakpour S, Zadehnazari A. The production of functionalized multiwall carbon nanotube/amino acid-based poly(amide-imide) composites containing a pendant dopamine moiety. Carbon 2013 56 27-37. 

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