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Biomolecules and Complex Biological Entities
Published in Simona Badilescu, Muthukumaran Packirisamy, BioMEMS, 2016
Simona Badilescu, Muthukumaran Packirisamy
Proteins are important, not only because they catalyze all of the reactions in living cells, but also due to their role in controlling virtually all the cellular processes. Proteins act as catalysts, regulate transport across cell membranes, and control expression of genes and replication of genetic material. In addition, proteins contain the information regarding the folding of protein into a three-dimensional structure, as well as the stability of this structure within their amino acid sequences. The protein’s specific function in the body is determined by its three-dimensional shape, which results from the sequence of amino acids. In addition to their function in the formation of proteins, amino acids have many other biologically important roles. For example, amino acids such as glycine and glutamate, which are found in most proteins, also function as neurotransmitters that inhibit and amplify, respectively, the transmission of nerve impulses in cells. A nonstandard amino acid called carnitine transports fatty acids into muscle cells for energy production. Many amino acids are used to synthesize molecules other than proteins. For example, tryptophan, an essential amino acid found in proteins such as casein and fibrin, is a precursor of serotonin, which is a neurotransmitter important for the regulation of mood. On the other hand, glycine takes part in the biosynthesis of porphyrins such as heme, a component of the hemoglobin molecules found in red blood cells.
Amino Acids and Vitamin Production
Published in Debabrata Das, Soumya Pandit, Industrial Biotechnology, 2021
L-lysine is required for calcium absorption and collagen formation (to improve bone and muscle health). L-lysine is a precursor to the formation of L-carnitine. Carnitine is required for the conversion of fatty acids to energy. It is required for the synthesis of enzymes, antibodies, and some hormones. It is also needed for defence against chronic viral diseases. Deficiency of L-lysine can cause symptoms such as anaemia, hypothyroidism, weakened immune system, weak bones, and muscles etc. L-lysine is available as capsules, powders, tablets and other forms which are used as supplements by athletes and weightlifters.
Substrate metabolism during exercise: Sexual dimorphism and women’s specificities
Published in European Journal of Sport Science, 2022
Nathalie Boisseau, Laurie Isacco
Data obtained in rodents and humans suggest that oestrogen significantly contributes to the regulation of substrate metabolism at rest and during endurance exercise (Gavin, Kohrt, Klemm, & Melanson, 2018; Tarnopolsky, 2008; Vieira-Potter, Zidon, & Padilla, 2015). As summarized in a book chapter, the activity of lipoprotein lipase (LPL), carnitine palmitoyltransferase I (CPT-I), and short-chain β-hydroxy acyl-CoA dehydrogenase (β-HAD) in skeletal muscle is higher, while hepatic glycogen utilization is lower in animals treated with 17β-oestradiol (E2) compared with untreated controls (Isacco & Boisseau, 2016). On the other hand, the activity of β-HAD, CPT-I and LPL is not different in men supplemented with E2 and in women (Isacco & Boisseau, 2016). E2 administration to men and to amenorrhoeic women reduces RER, CHO kinetics and oxidation rates, and increases plasma FFA concentrations and fat oxidation rates during moderate-intensity prolonged exercise. Conversely, it does not seem to have any effect on whole-body lipolysis (Carter, McKenzie, et al., 2001) and on muscle glycogen utilization (Devries, Hamadeh, Graham, & Tarnopolsky, 2005). A study in which healthy women underwent pharmacological suppression of gonadotropin-releasing hormone followed by replacement of ovarian hormones found that E2 reduces CHO oxidation rates by decreasing muscle glycogen utilization and Rd (muscle glucose uptake) (D’Eon et al., 2002). E2 supplementation in men also upregulates the messenger ribonucleic acid (mRNA) level of peroxisome proliferator-activated receptor α and β (PPAR-α, PPAR-β), sterol regulatory element-binding protein-1c, CPT-I, hormone sensitive lipase, glucose transporter type 4, and glycogen synthase (Tarnopolsky, 2008). E2 supplementation in men leads to upregulation of peroxisome proliferator-activated receptor-γ coactivator 1 α (PGC-1α) and of the microRNA miR-29b (predicted to regulate PGC-1α), and to higher mitochondrial gene expression of medium-chain acylCoA dehydrogenase, which is involved in fat utilization (Maher, Akhtar, Vockley, & Tarnopolsky, 2010) (Figure 1).