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Lysinuric protein intolerance
Published in William L. Nyhan, Georg F. Hoffmann, Aida I. Al-Aqeel, Bruce A. Barshop, Atlas of Inherited Metabolic Diseases, 2020
William L. Nyhan, Georg F. Hoffmann, Aida I. Al-Aqeel, Bruce A. Barshop
The defective transport in LPI is expressed in cultured fibroblasts [9]. Labeled lysine and the nonmetabolizable analog, homoarginine [44], were found not to display the trans-stimulated efflux that occurs in the presence of a cationic amino acid on the other side of the membrane [9, 45, 46]. Heterozygotes were found to display approximately 50 percent of control activity [9].
The Modification of Lysine
Published in Roger L. Lundblad, Chemical Reagents for Protein Modification, 2020
Guanidation of proteins is a reaction which is fairly specific for ∊-amino groups.139 This modification involves the reaction of O-methylisourea with lysyl residues at basic pH (pH >9) to yield homoarginine (Figure 50). This reaction is fairly slow and generally takes several days to go to completion. Bregman and co-workers140 examined the modification of the single lysyl residue in glucagon. In this study 3.4 g O-methylisourea (O-methylisourea hydrogen sulfate) was dissolved in 20 ml H2O and 6.0 g Ba(OH)2 added followed by filtration or centrifugation to remove the resulting BaSO4. The pH of the solution was adjusted to 11.0 and 200 mg glucagon added. The reaction was allowed to proceed for 8 h at 4°C and was terminated by the addition of glacial acetic acid. The products of the reaction were purified on Sulfopropyl-Sephadex. Guanidation of human recombinant erythropoietin has been accomplished with either O-methylisourea (Figure 50) or l-guanyl-3,5-dimethylpyrazole (Figure 51).141 Seven of the eight lysine residues were modified with O-methylisourea while all eight lysine residues were modified with l-guanyl-3,5-dimethylpyrazole. Both derivatives demonstrated increased biological activity.
Quantification of serum homoarginine, methylated arginine and inhibin-A levels in a high-risk pregnancy
Published in Journal of Obstetrics and Gynaecology, 2022
Hatice Banu Keskinkaya, Sedat Abuşoğlu, Ali Ünlü, Mehmet Nuri Atalar, Setenay Arzu Yilmaz
Methylarginines [ADMA (Asymmetric dimethylarginine) SDMA (Symmetric dimethyl-arginine), L-NMMA (NG-monomethyl-L-arginine)] are arginine derivatives formed as a result of methylation of post-translational modification of arginine residues in nucleoproteins (Vogl et al. 2015; Lüneburg et al. 2017). ADMA (C8H18N4O2-known as guanido analog of L-arginine, a derivative amino acid and is an endogenous inhibitors of nitric oxide synthase (NOS), it has a critical role in managing nitric oxide (NO) synthesis (Staab et al. 2015; Xuan et al. 2017). L-Homoarginine (C7H16N4O2) is a basic, impure cationic amino acid longer than L-arginine containing a longer carbon chain with an additional CH2 group, it is homologous of L-arginine. It is produced by kidneys from L-lysine through transmission of L-arginine glycine aminotransferase (AGAT, EC 2.1.4.1) enzyme (Rodionov et al. 2014; Fulton et al. 2019). It is believed that h-Arg level does not change due to a series of physiological and pathological conditions (Lüneburg et al. 2014; Liu et al. 2019). While h-Arg is an alternative but less effective substrate for NOS, ADMA directly serves as an inhibitor.
Prolonged consumption of grass pea (64 g/Cu/day) along with millets and other cereals causes no neurolathyrism
Published in Nutritional Neuroscience, 2021
R. Hari Kumar, Arjun Khandare, A. Laxmaiah, I. Meshram, N. Arlappa, Vakdevi Validandi, K. Venkaiah, P. Amrutha Rao, P. V. Sunu, V. Bhaskar, G. S. Toteja
Homoarginine (1.5% homoarginine) was one of the non-protein amino acid that has been characterized from grass pea seeds [17,18]. However, its importance in human nutrition and health never discussed much. Homoarginine is now established as a normal metabolite in humans [19]. In recent years nitric oxide has emerged as the most important signaling molecule both in the cardiovascular system and cerebral metabolism [20]. The health benefits of NO are now universally recognized by the scientific community [37,38]. Arginine is the natural substrate for nitric oxide synthase (NOS), whereas homoarginine is a poor substrate. And grass pea can make a valuable natural dietary source of homoarginine. If we compare both arginine and homoarginine for the endogenous production of NO as a substrate homoarginine could have certain advantages over arginine because of homoarginine is a poor substrate for hepatic arginase. As well as it acts as a weak inhibitor of arginase activity from several sources. Moreover, homoarginine following a grass pea meal in volunteers homoarginine has been detected in the blood even 24 h after grass pea consumption [39]. Homoarginine in grass pea seeds would thus have a dual role in raising endogenous NO levels by being a readily available substrate for NOS and also by indirectly raising arginine levels due to its weak inhibition of arginase activity.
Relationship between exercise intervention and NO pathway in patients with heart failure with preserved ejection fraction
Published in Biomarkers, 2018
Flavia Baldassarri, Edzard Schwedhelm, Dorothee Atzler, Rainer H. Böger, Kathrin Cordts, Bernhard Haller, Axel Pressler, Stephan Müller, Christiane Suchy, Rolf Wachter, Hans-Dirk Düngen, Gerd Hasenfuss, Burkert Pieske, Martin Halle, Frank Edelmann, André Duvinage
As exercise is also closely linked to the nitric oxide (NO) system (Schuster et al.2012), exercise training seems to be a promising way to improve vascular function and NO pathway biomarkers. Endothelial NO release has a vasodilatory effect (Tousoulis et al.2012), whereas oxidative stress or pathophysiological conditions, such as vascular injury, stimulate the production of methylated arginine derivatives, such as asymmetric dimethylarginine (ADMA) (Alter et al.2016). Therefore, methylarginine-mediated NO synthase inhibition leads to secondary endothelial dysfunction (Cardounel et al.2007). In contrast to these methylated arginine derivatives, low circulating L-homoarginine (L-hArg) concentrations are independently associated with mortality (Atzler et al.2013).