An accurate method for correcting unknown amino acid losses from protein hydrolyzates

Robel, Edward J.; Crane, Alan B.

doi:10.1016/0003-2697(72)90186-8

Cited by 36 publications

(44 citation statements)

References 6 publications

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“…Standard correction factors have been developed (for example, TNO, The Netherlands, 22 h HCl hydrolysis at 110°C: threonine, 1·05; serine, 1·10; valine, 1·07; isoleucine, 1·08), but the response to hydrolysis time is non-linear and varies among types of protein, foods and other biological materials. A more appropriate solution is to derive, using sequential hydrolysis times, curvilinear mathematical relationships describing the simultaneous amino acid release from a protein and amino acid destruction during hydrolysis (Robel & Crane, 1972). Taking into account the estimated rate of release of amino acids and their subsequent rate of destruction during hydrolysis and based on extrapolation, these mathematical models can be used to accurately predict the content of all amino acids from a single 24 h hydrolysis.…”

Section: Hydrolysis Intervalmentioning

confidence: 99%

Amino acid availability: aspects of chemical analysis and bioassay methodology

Moughan

2003

Nutr. Res. Rev.

109

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It is important to be able to characterise foods and feedstuffs according to their available amino acid contents. This involves being able to determine amino acids chemically and the conduct of bioassays to determine amino acid digestibility and availability. The chemical analysis of amino acids is not straightforward and meticulousness is required to achieve consistent results. In particular and for accuracy, the effect of hydrolysis time needs to be accounted for. Some amino acids (for example, lysine) can undergo chemical modification during the processing and storage of foods, which interferes with amino acid analysis. Furthermore, the modified amino acids may also interfere with the determination of digestibility. A new approach to the determination of available lysine using a modified in vivo digestibility assay is discussed. Research is required into other amino acids susceptible to structural damage. There is recent compelling scientific evidence that bacterial activity in the small intestine of animals and man leads to the synthesis and uptake of dietary essential amino acids. This has implications for the accuracy of the ilealbased amino acid digestibility assay and further research is required to determine the extent of this synthesis, the source of nitrogenous material used for the synthesis and the degree of synthesis net of amino acid catabolism. Although there may be potential shortcomings in digestibility assays based on the determination of amino acids remaining undigested at the terminal ileum, there is abundant evidence in simple-stomached animals and growing evidence in human subjects that faecal-based amino acid digestibility coefficients are misleading. Hindgut microbial metabolism significantly alters the undigested dietary amino acid profile. The ileal amino acid digestibility bioassay is expected to be more accurate than its faecal-based counterpart, but correction of the ileal amino acid flow for amino acids of endogenous origin is necessary. Approaches to correcting for the endogenous component are discussed.Protein: Amino acid availability: Lysine: Digestibility: Bioassays Abbreviation: FDNB, 1-fluoro-2, 4-dinitrobenzene.

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Section: Hydrolysis Intervalmentioning

confidence: 99%

Amino acid availability: aspects of chemical analysis and bioassay methodology

Moughan

2003

Nutr. Res. Rev.

109

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“…To measure PAAs (including peptides that can produce Gly during hydrolysis), we improved a previously reported nonlinear least-squares extrapolation method, [6] and adapted it to our approach using iSTDs (Supporting Information, Section 1). Briefly, biological samples were spiked with iSTDs, and the mixtures were hydrolyzed with 6 N hydrochloric acid (HCl) at 110 °C for t = 6, 12, 24, 48, and 96 h. Figure 2 illustrates the compartment model describing the simultaneous yield and decay processes of PAAs during hydrolysis.…”

mentioning

confidence: 99%

“…We improved the compartment model [6] using iSTDs and Monte Carlo fitting to measure proteome amino acids, since in principle at any given time point the MS measured levels of amino acids are not true hydrolysis yields (degradation occurs simultaneously). For PAA-Gly measurements, the reproducibility of h and l is relatively poor, which is similar to the results of previous studies.…”

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confidence: 99%

“…For PAA-Gly measurements, the reproducibility of h and l is relatively poor, which is similar to the results of previous studies. [6] To accurately measure h and l , multiple time points are required both before and after the levels of hydrolyzed amino acids reach their respective maxima. However, this is challenging because sample preparation includes a drying step and non-hydrolyzed proteins can interfere with LC-MS/MS detection.…”

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confidence: 99%

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Quantitative Method to Investigate the Balance between Metabolism and Proteome Biomass: Starting from Glycine

Carroll

et al. 2016

Angew Chem Int Ed

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The balance between metabolism and biomass is very important in biological systems; however, to date there has been no quantitative method to characterize the balance. In this methodological study, we propose to use the distribution of amino acids in different domains to investigate this balance. It is well known that endogenous or exogenous amino acids in a biological system are either metabolized or incorporated into free amino acids (FAAs) or proteome amino acids (PAAs). Using glycine (Gly) as an example, we demonstrate a novel method to accurately determine the amounts of amino acids in various domains using serum, urine, and cell samples. As expected, serum and urine had very different distributions of FAA- and PAA-Gly. Using Tet21N human neuroblastoma cells, we also found that Myc(oncogene)-induced metabolic reprogramming included a higher rate of metabolizing Gly, which provides additional evidence that the metabolism of proliferating cells is adapted to facilitate producing new cells. It is therefore anticipated that our method will be very valuable for further studies of the metabolism and biomass balance that will lead to a better understanding of human cancers.

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“…However, the latter strategy has limitations since the hydrolytic losses of tryptophan may differ across proteins. In the presently reported study, this impasse is overcome by using a least-squares nonlinear regression (Darragh, Garrick, Moughan, & Hendriks, 1996;Robel & Crane, 1972) to predict the loss rates of protein-bound tryptophan, synthetic tryptophan, 5-methyl-tryptophan and a-methyl-tryptophan directly. The least-squares nonlinear regression method models amino acid hydrolysis and degradation during hydrolysis and permits an accurate prediction of the amino acid content of a protein source (Darragh et al, 1996).…”

Section: Introductionmentioning

confidence: 98%