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Single Amino Acids
Published in Luke R. Bucci, Nutrition Applied to Injury Rehabilitation and Sports Medicine, 2020
Ornithine is a dibasic amino acid derived from arginine that is not incorporated into proteins. Ornithine serves as a metabolic intermediate for production of urea, polyamines, and other amino acids (directly forms citrulline via the urea cycle, and glutamate or proline via A-pyiroline-5-carboxylate).330 Ornithine-α-ketoglutarate (OKG) is a manufactured ionic salt consisting of one molecule of α-ketoglutarate with each carboxy group bound to the end amino group of an ornithine molecule.330 OKG consists of one α-ketoglutarate per two ornithine molecules. α-ketoglutarate is the oxo acid corresponding to deaminated glutamine. Since α-ketoglutarate is rapidly absorbed and metabolized and is an efficient precursor for glutamine, and since ornithine levels are elevated whenever arginine levels are elevated, and arginine has shown beneficial properties for the healing process (see previous section in this chapter), the combination of ornithine and α-ketoglutarate was thought to possibly influence protein metabolism in a positive manner. These effects have indeed been observed numerous times for OKG in experimental and clinical studies, and these effects have not been seen when either ornithine or α-ketoglutarate alone has been examined.330
The Sparse-Fur (Otcspf) and Abnormal Skin and Hair (Otcash) Mutations, Chromosome X
Published in John P. Sundberg, Handbook of Mouse Mutations with Skin and Hair Abnormalities, 2020
John P. Sundberg, Donald P. Doolittle
Ornithine transcarbamylase is a mitochondrial enzyme in the urea cycle that catalyzes the formation of citrulline from carbamoyl phosphate and ornithine.6 Mutant forms of this enzyme have been described in sparse-fur and in abnormal skin and hair mice.2,7 The enzymatic abnormality can be detected in the liver, duodenum, jejunum, and ileum.8 Mouse ornithine transcarbamylase is a trimer, similar to that in other species. The sparse-fur mutation does not affect the molecular weight of this enzyme. The affinity for ornithine and norvaline is decreased in mutant mice.9 Livers of hemizygous abnormal skin and hair mice synthesize two distinct ornithine transcarbamylase precursor polypeptides; one is normal in size, and the second is elongated. Both enzymes are processed by mitochondria, but only the one of normal size is assembled into the active trimer.10 The molecular lesion is a C to A transversion of the ornithine transcarbamylase gene in the sparse-fur mouse mutation that alters a histidine residue to an asparagine residue at amino acid 117.11 Correction of this enzymatic deficiency has been successful using transgenic approaches.12–16
Micronutrient Supplementation and Ergogenesis — Amino Acids
Published in Luke Bucci, Nutrients as Ergogenic Aids for Sports and Exercise, 2020
Thus, oral ornithine supplementation has been demonstrated to affect physiological parameters that are of interest to athletes, especially weightlifters and bodybuilders. Whether a practical benefit from ornithine supplementation can be sustained in athletes remains to be determined.
Fumarate exerted an antihypertensive effect and reduced kidney injury molecule (KIM)-1 expression in deoxycorticosterone acetate-salt hypertension
Published in Clinical and Experimental Hypertension, 2021
Osaze Edosuyi, Myung Choi, Ighodaro Igbe, Adebayo Oyekan
The previously described method (19) was modified and applied. Briefly, 40 µg of renal cortex/medulla was incubated with 1 M of magnesium chloride (MgCL2) at 37°C for 30 minutes. This was followed by the addition of 0.5 mL of L-arginine buffered solution with further incubation for 1 hour at 37°C. Lastly, 0.05 mL of Ninhydrin dissolved in 0.45 mL of acetic acid and 0.05 mL of phosphoric acid solution (developer solution) was added and samples were incubated for 1 hour at 95°C. Samples were kept at 37°C for 15 minutes and read spectrophotometrically at 530 nm. The same procedure was repeated for standard concentrations of ornithine (1, 5, 10, 25, 50 and 100 µM). Blank solution contained 0.01 mL of 1 M (95 mg/ml) magnesium chloride + 0.49 mL of L-arginine buffer + 0.5 mL of Developer solution.
Drug discovery through the isolation of natural products from Burkholderia
Published in Expert Opinion on Drug Discovery, 2021
Adam Foxfire, Andrew Riley Buhrow, Ravi S. Orugunty, Leif Smith
The biosynthetic gene cluster for production of Orn is well characterized [15]. Orn production is regulated by environmental iron concentration (Fur regulon) with optimal production reached at 4 µM environmental ferric iron, and production is generally negligible at concentrations above 15 µM. Additionally, growing Orn-producing strains in iron-rich media prevented later uptake of Orn by the strain [25]. Ornithine seems to be the limiting factor of Orn synthesis, and as such supplementation of media with 20 mM ornithine increases Orn synthesis by 2.5-fold. Although a putrescine (decarboxylated ornithine) residue is present in the final structure of Orn, supplementation of media with putrescine did not increase Orn synthesis. Whereas, supplementation of media with ornithine, arginine, and proline did increase the synthesis of Orn [25]. Interestingly, malleobactin (Figure 1(e)) biosynthesis is related to the biosynthetic pathway of Orn. Franke et al. [45] were able to reconstruct the biosynthesis of Orn from the malleobactin biosynthetic gene cluster by substitution of an adenylation domain of the Orn nonribosomal peptide synthetase (NRPS) into the related malleobactin NRPS.
Metabolomics reveals the renoprotective effect of n-butanol extract and amygdalin extract from Amygdalus mongolica in rats with renal fibrosis
Published in Artificial Cells, Nanomedicine, and Biotechnology, 2021
Wanfu Bai, Qing Liu, Hong Chang, Quanli Liu, Chen Gao, Yingchun Bai, Hongbing Zhou, Songli Shi
Ornithine can improve athletic performance through anabolic and wound-healing effects, and it can enhance immune function in cells. L-Ornithine is located in the mitochondria and cytoplasm [28]. Moreover, ornithine is associated with cystinuria, hyperdibasic aminoaciduria, and lysinuric protein intolerance, which are genetic metabolic defects. Ornithine is produced in the urea cycle through the cleavage of urea from arginine [26]. L-Ornithine is also a precursor of proline, citrulline, and arginine. Proline is the elementary element of collagen tissue and can promote collagen synthesis and deposition at the lesion site. Ornithine metabolism is involved in the arginine biosynthesis pathway. Arginine biosynthesis may reduce renal tubular interstitial fibrosis and ameliorate renal function [29].