Phanerosporic acid

Boronic acid compounds have been used, because of their unique structural features, for the development of potent enzyme inhibitors, boron neutron capture agents for cancer therapy, and as antibody mimics that recognize biologically important saccharides. Consequently, there has been a surge of interests in boronic acid compounds. This study reviews the recent development in this area during the last six years.

The gastric digestion of proteins is influenced by the pH and the gastric pH fluctuates after food consumption. However, the dynamics of gastric pH still need to be quantitatively understood. Proteins in food strongly influences the gastric pH. Therefore, we studied the interaction between acid and proteins, including the buffer reaction and the acid diffusion in protein gels. The buffer capacity of proteins stems from its content of ionizable amino acid side groups. Based on this, we set up a model and method to parameterize the buffer capacity of proteins. Moreover, the liberated carboxyl and amino groups during enzymatic hydrolysis of protein can also contribute to the buffer capacity. While we expected protons to diffuse faster than pepsin, we found that the penetration distance of acid is comparable to that of pepsin. The buffer reaction caused the acid to concentrate tenfold in the gel compared to the bulk acid concentration. Therefore, we postulated that the buffer reaction reduces acid diffusivity in gels.

We have developed a multiplexed quantitative analysis method for carboxylic acids by liquid chromatography high resolution mass spectrometry. The method employs neutron encoded (NeuCode) methylamine labels ((13)C or (15)N enriched) that are affixed to carboxylic acid functional groups to enable duplex quantitation via mass defect measurement. This work presents the first application of NeuCode quantitation to small molecules. We have applied this technique to detect adulteration of olive oil by quantitative analysis of fatty acid methyl amide derivatives, and the quantitative accuracy of the NeuCode analysis was validated by GC/MS. Currently, the method enables duplex quantitation and is expandable to at least 6-plex analysis.