Amino acids modified

Miniaturized columns have provided a decisive advantage in speed. Uracil, phenol, and benzyl alcohol were separated in 20 seconds by CEC in an 18 mm column with a propyl reversed phase.29 A19 cm electrophoretic channel was etched into a glass wafer, filled with a y-cyclodextrin buffer, and used to resolve chiral amino acids from a meteorite in 4 minutes.30 A 6 cm channel equipped with a syringe pump to automate sample derivatization was used to separate amino acids modified with fluorescein isothiocyanate.31 Nanovials have been used to perform tryptic digests on the 15 nL scale for subsequent separation on capillary Electrophoresis.32 A microcolumn has also been used to generate fractions representing time-points of digestion from a 40 pL sample.33 A disposable nanoelectrospray emitter has been... 

K.D. Gleria, H.A.O. Hill, V.J. Lowe, and D.J. Page, Direct electrochemistry of horse-heart cytochrome c at amino acid-modified gold electrodes. J. Electroanal. Chem. 213, 333-338 (1986). 

The peptide H2N-CH2-CO-NH-CH(CH3)-COOH is named glycylalanine and symbolised as Gly-Ala. The amino acid with the free -COOH group is chosen as the parent. The name of the other amino acid, modified by the suffix -yl, becomes a prefix to it. 

Amino acid-modified furocoumarins were prepared by condensation of the T-hydroxysuccinimide ester of 3-(2,3,5-trimethyl-7-oxofuro[3,2-g]chromen-6-yl)propanoic acid 51 with amino acids <2003JPH177>. Ethyl 3-(7-hydroxy-4-methyl-2-oxo-2/7-3-chromenyl)propanoate 49, prepared in 56% yield by Pechmann condensation of resorcinol and diethyl 2-acetylglutarate in the presence of HCl, was condensed with 3-chlorobutan-2-one in the presence of base to give propanoate 50 (Scheme 4). The MacLeod method was then used to fuse a furan ring to the benzopyran-2-one system. Heating 50 with NaOH solution (1 M) readily cyclized it into the corresponding psoralen furocoumarin 51 with simultaneous hydrolysis of the ester. 

A few years ago, we began a research program to develop methods of analysis which would involve the use of FAB and a high performance tandem mass spectrometer. The tandem instrument was the first triple sector mass spectrometer to be designed and built by a commercial instrument company (Kratos of Manchester, U.K.). The first mass spectrometer of the combination is a double focussing Kratos MS-50 which is coupled to a low resolution electrostatic analyzer, which serves as the second mass spectrometer U). This FAB MS-MS combination has been used to verify the structures of an unknown cyclic peptide (2), a new amino acid modified by diphtheria toxin (3), and an ornithine-containing lipid (4). A number of methods have also been worked out which rely on this instrumentation. They Include the structural determination of cyclic peptides (5), nucleosides and nucleotides (6), and unsaturated fatty acids (7) and the analysis of mixtures of both anionic (8) and cationic surfactants (9). 

Chemical structures of several chelators. Ferroxamine (ferrioxamine) without the chelated iron is deferoxamine. It is represented here to show the functional groups the iron is actually held in a caged system. The structures of the in vivo metal-chelator complexes for dimercaprol, succimer, penicillamine, and unithiol (not shown), are not known and may involve the formation of mixed disulfides with amino acids. (Modified and reproduced, with permission, from Meyers FH, Jawetz E, Goldfien A Review of Medical Pharmacology, 7th ed. McGraw-Hill, 1980.)... 

FIGURE 72.3. Molecular organization of arrAB (periplasmic arsenate reductase) and arsDABC (cytoplasmic arsenate reductase) of Shewanella strain ANA-3 (from GenBank Accession no. AY271310). arrAB gene cluster is located upstream in the opposite orientation to an arsDABC. aa-amino acid (modified Ifom Saltikov and Newman, 2003 Silver and Phung, 2005). 

Faicnt amino acid Modified fonn Vitamin cofaclor... 

Parent amino acid Modified form Vitamin cofactor... 

Amino Acid Classes Biologically Active Amino Acids Modified Amino Acids in Proteins Amino Acid Stereoisomers Titration of Amino Acids Amino Acid Reactions PEPTIDES PROTEINS... 

Rare exceptions are bacterial membrane proteins, which contain a few D-Amino Acids, modified amino acids - primarily lysine (see here) and proline (see here), and occasional incorporation of the rare amino acid, selenocysteine). 

Covalent incorporation of designed amino acids modifies the structure of the determinant groups of the proteins and prevents the formation of new determinants. 

Figure 1. Sector rule for a-amino acids. (Modified from Jorgensen, 1971.) The carboxylic group viewed from the top in amino acids.

We recently reported a kind of novel hydrogelators based on amino acid modified or carboxylic based (-)-menthol derivate (compounds la-ld in Fig. 3.2) [17]. The results show that only amino acid modified compounds can form gels in aqueous ethanol solution or pure water, la can form a stable hydrogel in pure water... 

Dutta A, DuBois DL, Roberts JAS, Shaw WJ (2014) Amino acid modified Ni catalyst exhibits reversible H2 oxidation/production over a broad pH range at elevated temperatures. Proc Natl Acad Sci U S A 111(46) 16286-16291. doi 10.1073/pnas.l416381111... 

Finot, P.A., Magnenot, E., Mottu, F. and Bujard, E. (1978) Biological availability and metabolic fate of amino acids modified by technological processing. Ann. Nutr. Alim. 32, 325. 

Casettari, L., VUasahu, D., Lam, J.K., Soliman, M., Ilium, L., 2012. Biomedical apphcations of amino acid-modified chitosans a review. Biomaterials 33 (30), 7565-7583. 

Scheme 12-5 Schematic presentation of the synthesis of thiolactone peptide Xni with N-Boc protected amino acids (modified fi-om [36])...

Tables 9-9 and 9-10 give data on the anticorrosion activity of chemicals with a central nitrogen atom and the result of different a-amino acids modified on the amino group, respectively. A newly introduced carboxymethyl or phosphonomethyl group also increases the effectiveness of the inhib-...

FIGURE 8. Reaction of carbon disulfide with nucleophilic center in an amino acid. Modified from Cohen et... 

Protein-modified siioxanes have recently drawn commercial attention. One major advantage is the possibility of combining film formation and moisture retention properties of proteins with lubricity and spreadability of silicones. Amino acid-modified silicones are obtained by the reaction of an alkali salt of an amino acid and an organo-modified polysiloxane containing epoxy groups (Fig. 10) [26]. These new copolymers show promising potential for cosmetic applications. 

Fig. 158. Fine regulation by isoenzymes - biosynthesis of the aromatic amino acids (modified from Lingens 1969).

Pronase Digestion to Yield Single Amino Acids Modified by OPs... 

Digestion of OP-freafed human plasma proteins wifh pronase 5delds free amino acids modified by OP (Black ef al., 1999). Human plasma freafed wifh sarin or soman contains OP-serine (from BChE) and subsfan-tially greater amoimts of OP-tyrosine (from albumin and possibly other proteins as well Black et al., 1999). 

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