Gaussian and linear deconvolution of LC-MS/MS chromatograms of the eight aminobutyric acid isomers

Abstract

Isomeric molecules present a challenge for analytical resolution and quantification, even with MS-based detection. The eight-aminobutyric acid (ABA) isomers are of interest for their various biological activities, particularly γ-aminobutyric acid (GABA) and the d- and l-isomers of β-aminoisobutyric acid (β-AIBA; BAIBA). This study aimed to investigate LC-MS/MS-based resolution of these ABA isomers as their Marfey's (Mar) reagent derivatives. HPLC was able to separate three Mar-ABA isomers l-β-ABA (l-BABA), and l- and d-α-ABA (AABA) completely, with three isomers (GABA, and d/l-BAIBA) in one chromatographic cluster, and two isomers (α-AIBA (AAIBA) and d-BABA) in a second cluster. Partially separated cluster components were deconvoluted using Gaussian peak fitting except for GABA and d-BAIBA. MS/MS detection of Marfey's derivatized ABA isomers provided six MS/MS fragments, with substantially different intensity profiles between structural isomers. This allowed linear deconvolution of ABA isomer peaks. Combining HPLC separation with linear and Gaussian deconvolution allowed resolution of all eight ABA isomers. Application to human serum found a substantial level of l-AABA (13 μM), an intermediate level of l-BAIBA (0.8 μM), and low but detectable levels (<0.2 μM) of GABA, l-BABA, AAIBA, d-BAIBA, and d-AABA. This approach should be useful for LC-MS/MS deconvolution of other challenging groups of isomeric molecules.

β-aminoisobutyric Acid, l-BAIBA, Is a Muscle-Derived Osteocyte Survival Factor

“…Muscle CM were freeze-dried, derivatized using Marfey’s reagent, and then quantitated by liquid chromatography-mass spectrometry (LC-MS) as described previously (Vemula et al, 2017). Contraction stimulated L-BAIBA production in all muscle, EDL and soleus, male and female, but to a greater extent in aged muscle compared with young muscle (Figure 5A).…”

Quantification of aminobutyric acids and their clinical applications as biomarkers for osteoporosis

“…But the current quantification methods for aminobutyric acid isomers/enantiomers using LC-MS are typically compromised with unresolved peak separations, large sample volumes, time-consuming derivatization, and long analysis times 19,20 . An LC-MS/MS method, reported by Vemula et al (2017), is the only published method to separate eight isomeric aminobutyric acids simultaneously 21 . However, their derivatization process and LC-MS analysis was time and labor intensive and, more importantly, five out of the eight aminobutyric acid isomers/enantiomers could not be chromatographically separated.…”

Sphaerostilbellins, New Antimicrobial Aminolipopeptide Peptaibiotics from Sphaerostilbella toxica

“…L-Arg and Gly, present in the SCH peptaibols, were included among the derivatized standards for comparison but were absent from the samples, further confirming the differences among these compounds. It should be noted that relatively low absorbance for Aib and putrescine derivatives evident in chromatograms ( Figure S18 ) are likely due to slower derivatization reaction rates required for complete reaction with Marfey’s reagent [ 30 , 31 ].…”