Measurement of Acylcarnitine Substrate to Product Ratios Specific to Biotin-Dependent Carboxylases Offers a Combination of Indicators of Biotin Status in Humans

Abstract

This work describes a novel liquid chromatography tandem MS (LC-MS/MS) method for the determination of ratios of acylcarnitines arising from acyl-CoA substrates and products that reflect metabolic disturbances caused by marginal biotin deficiency. The urinary ratios reflecting reduced activities of biotin-dependent enzymes include the following: 1) the ratio of 3-hydroxyisovalerylcarnitine : 3-methylglutarylcarnitine (3HIAc : MGc) for methylcrotonyl-CoA carboxylase; 2) the ratio of propionylcarnitine:methylmalonylcarnitine (Pc : MMc) for propionyl-CoA carboxylase (PCC); and 3) the ratio of acetylcarnitine : malonylcarnitine (Ac : Mc) for acetyl-CoA carboxylase. To demonstrate the suitability of the LC-MS/MS method for biomonitoring, we measured the 3 ratios for 7 healthy adults at various time points (d 0, 14, and 28) during the induction of marginal biotin through the consumption of egg white. The mean change in the Pc : MMc ratio relative to d 0 was 5.3-fold by d 14 (P = 0.0049) and 8.5-fold by d 28 (P = 0.0042). The mean change in the 3HIAc : MGc ratio was 2.8-fold by d 14 (P = 0.0022) and 3.8-fold by d 28 (P = 0.0001). The mean change in the Ac : Mc ratio was 2.9-fold by d 14 (P = 0.03) and 4.7-fold by d 28 (P = 0.02). The results suggest that simultaneous assessment of ratios of multiple biotin-dependent pathways offers insight into the complex metabolic disturbances caused by marginal biotin deficiency. We hypothesize that one or a combination of the ratios might be more sensitive or robust with respect to other nutrient deficiencies or confounding metabolic processes.

Temporal development of genetic and metabolic effects of biotin deprivation. A search for the optimum time to study a vitamin deficiency

“…These compounds are derived from the accumulation of the substrates of 3-methylcrotonyl CoA carboxylase (MCC) [25] and of propionyl CoA carboxylase (PCC) [23] revealing metabolic blocks at these steps. These observations confirm our previous work [13,18], and are similar to the urine acylcarnitine levels and related substrate to product ratios recently reported by Bogusiewicz, et al [26], which likely increase human relevance of our observations. Furthermore, the urinary excretion of 3-HIV is consistent with a decrease in the lymphocytes PCC activity [27].…”

Scientific Opinion on Dietary Reference Values for biotin

“…Urinary excretion of 3HIA and 3HIA-carnitine was also shown to significantly increase in response to an oral challenge of leucine, an amino acid whose degradation requires MCC (Mock et al, 2002a;Mock et al, 2011). A decrease in PCC activity in lymphocytes and, more recently, an increase in the ratios of acylcarnitines in urine, arising from acyl-CoA substrates and their products, which reflect disturbances in biotin-dependent carboxylase activities, were also observed in response to induced biotin insufficiency (Stratton et al, 2006;Bogusiewicz et al, 2012).…”

Dietary Docosahexaenoic Acid and trans‐10, cis‐12‐Conjugated Linoleic Acid Differentially Alter Oxylipin Profiles in Mouse Periuterine Adipose Tissue

“…The ratio of enzymatic products to substrates in biological samples can be used as an index of enzymatic activity in the host organism and/or tissue [26,38,39]. To assess shifts in biochemical activity, ratios of products to substrates across known and theoretical enzymatic steps were calculated.…”