Amino acids conditions

Fig. S6. Separation of D,L-dansyl amino acids. Conditions 0.65 oiAf L 2>isopropyl-dien-Zn(II) 0.17 A NH,Ac to pH 9.0 with aqueous NI 35/65 CH,CN/H,0 T - 30 flowrate 2 tnl/min column 15 cm by 4.6 mm i.d. S iun Hypersil C solutes CySO H -cysteic acid Ser - serine Trp - tryptophan thr - threonine Norval - norvaline Leu w leucine Norleu - norleucine Phe phenylalanine. Detection at 254 nm. Reprinted with permission from LePage ef at. C246), Am/. Chem. Copyright 1979 by the American Chemical Society.

Fig. 5.15. Gas chromatogram of N-acetyl-n-propyl esters of 17 amino acids. Conditions glass column, 106 cm X 3 mm I.D., packed with a mixture (1 1) of 0.7% Carbowax 6000 on Chromosorb G (80— 100 mesh, HP) and 0.7% Carbowax 6000 plus 0.05% tetracyanoethyl pentaerythritol on the same support nitrogen flow-rate, 30 ml/min temperature programme, 6°C/min, 100-240°C. (Reproduced from J. Chromatogr., 36 (1968) 42, by courtesy of J.R. Coulter.)...

Fig. 5.20. GC separation of TMS-methylthiohydantoins of amino acids. Conditions borosilicate-glass column, 165 cm X 4 mm I.D., 2% (w/w) OV-17 on Gas-Chrom Q (80-100 mesh) nitrogen flow-rate, 50 ml/min temperature programme as indicated. (Reproduced from Anal. Biochem., 58 (1974) 549, by courtesy of Academic Press.)...

Fig. 1 HPLC analysis of 18 common amino acids. Conditions stationary phase CS-10 cation exchange mobile phase gradient of aqueous 0.01% TFA and ammonium acetate detection at the ELSD. (From Ref. 11.)...

Fig. 3 RP-HPLC analysis of a mixture of dansyl amino acids. Conditions stationary phase 4 /xm Nova Pak Cig mobile phase gradient of methanol and tetrahydrofuran versus aqueous phosphate buffer detection in a fluorescent detector excitation 338 nm, emission 455 nm. Amino acids are abbreviated by the one-letter system. (From Ref. 12.)...

Under the right conditions, hydrolysis of the eyanide A oceurs during the reaction to give the amino acid B. How could you make the amino acid Valine (TM 138) ... 

In each step of the usual C-to-N peptide synthesis the N-protecting group of the newly coupled amino acid must be selectively removed under conditions that leave all side-chain pro-teaing groups of the peptide intact. The most common protecting groups of side-chains (p. 229) are all stable towards 50% trifluoroacetic acid in dichloromethane, and this reagent is most commonly used for N -deprotection. Only /ert-butyl esters and carbamates ( = Boc) are solvolyzed in this mixture. 

Another protecting group of amines is 1-isopropylallyloxycarbonyl, which can be deprotected by decarboxylation and a /3-elimination reaction of the (tt-l-isopropylallyl)palladium intermediate under neutral conditions, generating CO2 and 4-methyl-1,3-pentadiene. The method can be applied to the amino acid 674 and peptides without racemization[437]. 

The condensation of thioacetic acid with amino acids under drastic conditions provides a useful new synthesis of thiazoles (Scheme 146) (668, 669). Instead of the amino acid, Af-acyl <279) or N-thioacylamino acids (278) are used. 

Amphoteric Detergents. These surfactants, also known as ampholytics, have both cationic and anionic charged groups ki thek composition. The cationic groups are usually amino or quaternary forms while the anionic sites consist of carboxylates, sulfates, or sulfonates. Amphoterics have compatibihty with anionics, nonionics, and cationics. The pH of the surfactant solution determines the charge exhibited by the amphoteric under alkaline conditions it behaves anionically while ki an acidic condition it has a cationic behavior. Most amphoterics are derivatives of imidazoline or betaine. Sodium lauroamphoacetate [68647-44-9] has been recommended for use ki non-eye stinging shampoos (12). Combkiations of amphoterics with cationics have provided the basis for conditioning shampoos (13). 

Hydrolysis. Although hydantoins can be hydroly2ed under strongly acidic conditions, the most common method consists of heating ia an alkaline medium to give iatermediate ureido acids (the so-called hydantoic acids), which are finally hydroly2ed to a-amino acids. 

In these cases, it is better to protect the carboxyl group. Optimized conditions for A/-acetylation have been studied (78). A/-Acylation can be utilized for protecting the amino group in the reaction of amino acids, for example in peptide synthesis. 

Biosynthesis of Protein. The dynamic equilibrium of body protein was confirmed by animal experiments using A/-labeled amino acids in 1939 (104). The human body is maintained by a continuous equilibrium between the biosynthesis of proteins and their degradative metabolism where the nitrogen lost as urea (about 85% of total excreted nitrogen) and other nitrogen compounds is about 12 g/d under ordinary conditions. The details of protein biosynthesis in living cells have been described (2,6) (see also Proteins). 

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