Tryptophan hydrochloride

Wieczorek, P. (1997). Factors influencing the transport of tryptophan hydrochloride through supported liquid membranes containing macrocyclic carriers. J. Membr. Sci., 127, 87-92. 

Reagents sulphuric acid 75%, cysteine hydrochloride 2.5%, tryptophan solution in hydrochloride acid to formation of tryptophan hydrochloride (lOOjig.mL-i in HCl O.IM). 

Getting an aliquot 50pg.mL-i of the sample, add 2.8mL of sulphuric acid 75%, shake in vortex, add O.lmL cysteine hydrochloride solution 2.5%, shake in vortex again, let in water-bath 45-50°C for 10 minutes, cool at room temperature and add ImL tryptophan hydrochloride solution, shake again in vortex. 

A millimolar solution of tryptophan hydrochloride in acidified water, pH 2.38, reaches an equilibrium to give a 50 50 ratio of cation to zwitterion. Fig. 8.1, right. What is this ratio going to be after you add 0.025 mol of aluminum sulfate to the solution ... 

A note on quaternary ammonium salts Converting tryptophan to tryptophan hydrochloride, TrpH CC, by addition of hydrochloric acid, HCl, is a common practice in medicinal chemistry and pharmacology. It converts the drugs which contain amino, —NH2, group - of which there are many - into water-soluble salts that can be administered intravenously. Read the fine print on the over-the-counter drug packages and you will see that most of them are in the form of HCl salts. 

Crystals of L-tryptophan hydrochloride and hydrobromide are iso-morphous with each other and the conformation of the amino acid cations is essentially the same in both crystals (405). The plane of the... 

Takigawa, T., T. Ashida, Y. Sasada, and M. Kakudo The Chrystal Structures of L-Tryptophan Hydrochloride and Hydrobromide. Bull. Chem. Soc. Japan 39, 2369-2378 (1966). 

In 1971, adrenodoxin, an iron-sulfur protein with a single tyrosine residue and no tryptophan was shown to fluoresce at 331 nm upon 280-nm excitation at neutral pH/20 1 On cooling from room temperature to 77 K, the emission maximum shifts to 315 nm. The redox state of the iron does not have any effect on the tyrosine emission. From these results, an exciplex between the excited singlet state of tyrosine and an unidentified group was suggested as the cause of the anomalous emission energy/2031 Later studies have shown that the excitation spectrum is a red-shifted tyrosine spectrum, that removal of the iron to form the apoprotein has no effect on the emission, and that heat, low pH, guanidine hydrochloride, urea, and LiCl all cause the emission... 

For horse liver alcohol dehydrogenase, denaturation by guanidine hydrochloride resulted in a decrease in phosphorescence lifetime parallel with loss of activity.(79) With urea as a denaturant, the decrease in phosphorescence lifetime appeared cooperative, and it is suggested that the denaturant loosened intramolecular interactions (such as hydrogen bonds), resulting in greater fluidity of the tryptophan environment.(80)... 

The synthesis of /./-pyridindolol 1064 started by acetonation of glyceric ester 1057 to give 1058, which was converted to the imidazoline 1059 by reaction with l,l-dimethyl-l,2-diaminoethane followed by acetylation. Its methylation gave 1060, which can be reduced to 1061 further reaction with tryptamine or tryptophan ester hydrochloride 1062 gave the respective diastreomeric mixture of carboline 1063 (80H947). Its conversion to racemic alkaloid d,/-pyridindolol 1064 could be readily achieved (79JOC535). 

Various antidepressants bupropion hydrochloride nefazodone hydrochloride trazodone hydrochloride L-tryptophan... 

Figure B3.5.5 Near-UV CD spectra. (A) Bovine a -casein peptide under a variety of conditions (data from Alaimo et al., 1999). Peptide concentration 0.631 mg/ml in 2 mM PIPES, 4 mM KCI, pH 6.75 scan rate 40 sec/nm path length 10 mm bandwidth 1.5 nm. The loss of aromatic dichroism with increasing temperature indicates denaturation, which is, however, not complete at 70°C or in 6 M guanidine hydrochloride. The shift in maximum wavelength indicates loss of tryptophan asymmetry, but less so of tyrosine. (B) Seed coat soybean peroxidase under native and denaturing conditions (data from Kamal and Behere, 2002). Protein concentration 15 pM and path length 10 mm. The negative aromatic band centered around 280 nm and the Soret band around 410 nm both disappear at 90°C, indicating the loss of net conformational asymmetry of the aromatic and heme chromophores.

The chiral cavitands 3.109 have been developed by combining the amino acid residue L-alanine with macrocyclic cavitands (calixarenes - Section 3.14).51 These ammonium ion receptors are able to complex a range of amino acids and their methylester hydrochloride salts, all of which contain an -NH3+ functionality capable of interaction with the carboxylate residues of the host. In general amino acids are bound only very weakly in aqueous solution, while association constants with the chiral methyl esters range from 620 M-1 for L-tryptophan methylester to 110 M-1 for L-alanine methylester. The methylester of glycine is not bound at all. Receptors related to 3.109 with variable four peptide loops arrayed around a central calixarene core have been used to bind to the surfaces of proteins. The... 

In 1991, Newkome and Lin 121 reported a series of acid terminated poly(ether amido) dendrimers (e.g., 3, 4), generated from the tetraacid core (1) and sequential use of the amino acid building block 2 (Scheme 7.1). These acid-terminated dendrimers were readily transformed 131 into the related polytryptophane analogues (5-7) by treatment with tryptophane methylester hydrochloride employing a common peptide coupling procedure (DCC 1-HBT in DMF). 141 The resultant chiral cascade series was examined via ORD/CD and the preliminary data indicate a linear relationship between optical rotation and the number of surface tryptophane moieties. 

The analytical method proposed by Pajot (1976) involves (a) incubating the protein of a known concentration in 6 M guanidine at pH 6.5-7 in the presence of 30 mM 2-mercaptoethanol for 30 min (if only a small amount of the protein is available, the incubation can be carried out directly in the fluorescence cuvette) and (b) measuring the fluorescence, excited at 295 nm and observed at 354 nm, yielded by the denatured protein in 6 M guanidine hydrochloride (tryptophanyl residues concentration 3-10 /xM). A linear calibration curve is obtained, thus allowing the free tryptophan fluorescence equivalents of the protein sample to be estimated by extrapolation. 

Pajot, P. (1976). Fluroescence of proteins in 6-M guanidine hydrochloride. A method for the quantitative determination of tryptophan. European Journal of Biochemistry, 63,263-269. 

The second derivative of the spectrum of a protein (d2A/dA2) can be used to evaluate the content of the three aromatic amino acids, tryptophan, tyrosine and phenylalanine, in a manner analogous to that discussed above for extinction coefficients (Levine and Federici 1982). The following expression holds in the presence of denaturing concentrations of guanidinium hydrochloride ... 

TRYPTAZINE DIHYDROCHLORIDE see TKK250 TRYPTIZOL see EAIOOO TRYPTIZOL HYDROCHLORIDE see EAIOOO (-)-TRYPTOPHAN see TNXOOO 1-TRYPTOPHAN see TNXOOO dl-TRYPTOPHAN see TNW500 dl-TRYPTOPHAN, pytolyzate 1 see TNX275 TRYPTOPHANE see TNXOOO 1-TRYPTOPHAN (FCQ see TNXOOO... 

As depicted in Scheme 8.5, L-tr) tophan methyl ester hydrochloride (13) was first treated with 1.1 equiv of piperonal in nitromethane at reflux temperature. Similar to D-tryptophan methyl ester hydrochloride, the highly stereoselective Pictet-Spengler reaction of L-tryptophan methyl ester hydrochloride with piperonal produced the hydrochloride salt of (lS,3S)-l,3-disubstituted-tetrahydro-p-carboline 14-HCl [17,25]. After neutralization of 14-HCl, compound 14 was obtained in 95% yield and with 99% ee. Compound 14 was then treated with 1.2 equiv of benzyl chloroformate in ethyl acetate at around 5 °C in the presence of 3 equiv of potassium carbonate powder to afford (lS,3S)-l,2,3-trisubstituted-tetra-hydro-p-carboline (15) in 94% yield. The base-catalyzed epimerization of... 

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