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Modifying and Optimizing 1H NMR for Amino Acid Analysis

Description

The parameters of microwave-assisted acid hydrolysis (MAAH) and 1H NMR highly affect the quantitative analysis of protein hydrolysates. Microwave-induction source, NMR spectral resolution, and data analysis are key parameters in the nuclear magnetic resonance – amino acid analysis (NMR-AAA) workflow

The parameters of microwave-assisted acid hydrolysis (MAAH) and 1H NMR highly affect the quantitative analysis of protein hydrolysates. Microwave-induction source, NMR spectral resolution, and data analysis are key parameters in the nuclear magnetic resonance – amino acid analysis (NMR-AAA) workflow where errors accrue due to lack of an optimized protocol. Hen egg white lysozyme was hydrolyzed using an 800W domestic microwave oven for varying time points between 10-25 minutes, showing minimal protein hydrolysis after extended time periods. Studies on paramagnetic doping with varying amounts of gadolinium chloride for increased NMR resolution resulted in little T1 reduction in a majority of amino acids and resulted in significant line broadening in concentrations above 1µM. The use of the BAYESIL analysis tool with HOD suppressed 1H-NMR spectra resulted in misplaced template peaks and errors greater than 1% for 10 of 13 profiled amino acids with the highest error being 7.6% (Thr). Comparatively, Chenomx NMR Suite (v7.1) analysis resulted in errors of less than 1% for 9 of 13 profiled amino acids with a highest error value of 3.6% (Lys). Using the optimized protocol, hen egg white lysozyme C was identified at rank 1 with a score of 64 in a Gallus gallus species wide AACompIdent search. This technique reduces error associated with sample handling relative to previously used amino acid analysis (AAA) protocols and requires no derivatization or additional processing of the sample prior to analysis.

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Created

Date Created
2017-05

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A Hydrogen (1H) Nuclear Magnetic Resonance (NMR) Method for Amino Acid Analysis

Description

Amino acid analysis (AAA) of egg white lysozyme and bovine Achilles tendon collagen was performed using 1H solution-state nuclear magnetic resonance (NMR) spectroscopy. The proteins were hydrolyzed in 6M HCL with and without 0.02% phenol at 110\u00B0C for 24, 48,

Amino acid analysis (AAA) of egg white lysozyme and bovine Achilles tendon collagen was performed using 1H solution-state nuclear magnetic resonance (NMR) spectroscopy. The proteins were hydrolyzed in 6M HCL with and without 0.02% phenol at 110\u00B0C for 24, 48, and 72 hours. For both proteins, 18 of 20 amino acids were characterized including hydroxyproline and hydroxylysine in collagen, using 1-dimensional (1D) and 2-dimensional (2D) NMR spectroscopy experiments. Errors ranging from <1% to 8% were seen in treatments with and without phenol. Both proteins could be correctly identified within their own species using the online database search AACompIdent. The proposed approach is a simple analytical technique that does not require the use of column separation or amino acid derivatization prior to compositional analysis.

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Created

Date Created
2014-05