Amino acid basic strength

Re-formation of the Taste of BMP. According to the above results, the taste of BMP might produced by the combination of the basic amino acid (Lys) at N-terminal and acidic amino acids at the middle part. To confrnn this idea, we prepared a mixed solution of the N-terminal dipeptide (Lys-Gly), the acidic tripeptide at the middle part (Asp-Glu-Glu) and C-terminal tripeptide (Ser-Leu-Ala) and examined the taste. We also studied tastes of a mixture in which a basic dipeptide fragment was replaced by Orn-p-Ala, a salty dipeptide, and a mixture in which Glu-Glu replaced an acidic tripeptide fragment. The result are shown in Table XIV. All of the combinations produced the same character of the taste as BMP. It means that the taste of BMP is mainly produced by the combined effect of the N-terminus basic dipeptide and the acidic tripeptide of the middle part. However, taste strength of the mixture became... 

The concentration of buffer is also a very important aspect in the optimization of the chiral resolution on these CSPs. It has been reported that an increase in buffer concentration caused a decrease in the retention and selectivity for all amino acids except for the basic amino acids. Therefore, the separation of basic amino acids is possible only with the most concentrated buffers. The buffers of concentrations in the 25-50-mM range were used for the chiral resolutions with some exceptions. In spite of this, few reports are available for the optimization of the chiral resolution by varying the ionic strength of the mobile phase. The effect of ionic strength of phosphate buffer on the chiral resolution of serine was carried out by Gubitz and Jellen [18] and the best resolution was achieved at 0.01 M concentration (Fig. 7). In another study, the concentration of ammonium acetate (0.001-0.01 M) was varied to optimize the chiral resolution of amino acids [19]. The effect of the concentration of ammonium acetate on the chiral resolution of amino... 

The effects of substituents on the acidic and basic strengths of imidazoles have been discussed by Hofmann1 and Pozharskii et al.3 in previous reviews. Precise data have been determined175 for the basicity of imidazole in D20-H20 mixtures. Perrin176 has developed methods based on the Hammett equation for predicting the pKa values in water of substituted imidazoles (and other heterocycles), while applications of the Hammett equation have also been made to 2-substituted imidazoles.177 Calculations of j>K values for 2-amino-imidazolium ions suggest that 2-aminoimidazoles are better regarded... 

Aminoimidazoles do not appear to exist to any great extent in the tautomeric imino forms.448 The C-amino groups have lower basic strength than aniline, and consequently alkylation occurs preferentially at a ring nitrogen. Amino substituents in the 2-position can generally be acylated and diazotized (usually in strongly acid medium), but 4-aminoimidazoles are more unstable and have not been extensively studied. 

In recent years capillary electro separations were found to be useful for the analysis of a variety of small molecules. Several variants of the basic technique- such as capillary zone electrophoresis, micellar electroki-netic chromatography, and capillary gel electrophoresis - are available. However, only a handful of reports are available on flavanone analysis (Cancalon and Bryan, 1993 Desiderio et ah, 2005). Typically the separations were performed on silica fused capillaries of 70-75 pm internal diameter packed with RPig or uncoated silica (Cancalon and Bryan, 1993 Desiderio et ah, 2005). One of the major strengths of the techniques is the separation of multiclasses of compounds, ranging from amino acids to carotenoids to flavonoids (Cancalon and Bryan, 1993). 

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