||Ashley E. Beck, Kristopher A. Hunt, and Ross P. Carlson, Measuring Cellular Biomass Composition for Computational Biology Applications, Processes 2018, 6(5), 38, doi:10.3390/pr6050038 p.14 table 3
||P.13 bottom paragraph: "Upon preparing for HPLC analysis, the lyophilized material was re-suspended in 100 µL 0.1 M HCl per mg biomass hydrolyzed. Different dilutions of the re-suspension were measured to ensure adequate detection of both more abundant and less abundant amino acids. Peak identity was confirmed for each amino acid by testing individual solutions of each amino acid. A representative chromatogram is shown in Figure 4. An internal standard, α-aminobutyric acid, was used in samples and standards alike for peak area normalization across injections. Standard curves were constructed, resulting in linear regressions with fits of 0.99 or greater. The experimental amino acid distribution and total protein quantification for the three bacterial species are shown in Table 3. Since cysteine and tryptophan were degraded during hydrolysis and methionine was present in low quantities with high variability (likely oxidized during hydrolysis), the distribution of these three amino acids was calculated according to the percentage found in the protein-coding genes of the genome. Reasonable correlations were observed between the experimentally measured and genome-predicted distributions (Figure A4, Appendix A). Interestingly, leucine content was observed to be consistently over-predicted in the genome and under-measured in the laboratory among the three species tested, although no explanation has been linked to this observation in the literature."