Amino Acid Quantitative Analysis

Amino Acid Quantitative Analysis N.Koen Introduction Amino acids give the basic building blocks of forming a protein and play an essential role in the energy metabolism, neurotransmission, and lipid transport. Their quantitative analysis is important for various uses, including disease diagnostics and in elucidating nutritional influences on physiology (Fromm & Hargrove, 2012). Amino acid levels in the body fluids are used to diagnose metabolic deficiencies. Deprived or excessive levels of amino acids can show different defects of deficiencies (Lanpher, 2006). Preparation requirements and sample clean-up make the procedure a slow procedure. While some protocols may provide adequate chromatographic methods and derivatization procedures, that makes it more sufficient and quicker. Leucine is an essential amino acid, which means that it cannot be manufactured in the body. It is also well represented in all the proteins in the body. In vivo leucine kinetics presents a theoretically valid index of protein turnover. C onsequently, isotopically labelled (2H, 3H, 13C, 14C or 15N) leucine is most commonly used for the study of protein metabolism in humans and animals (Fromm & Hargrove, 2012). Literature review Amino acid involvement 1. Amino acid analysis Leucine is an amino acid which is usually obtained by hydrolysis of most common proteins. It was among the first of amino acids to be discovered in 1819 in muscle fibre and wool (Bauman, et al., 1992). Leucine is present in large proportions in haemoglobin. This amino acid is also known for preventing the breakdown of muscle proteins caused by injury or stress (Lanpher, 2006). In addition, Leucine may be beneficial for people suffering from phenylketonuria. Leucine is an essential amino acid, so your body cannot produce it naturally but can only obtain it from food, including protein-rich animal food like fish, chicken, beef, also dairy and eggs. Leucine is classified as a hydrophobic amino acid due to its aliphatic isobutyl side chain. It is encod ed by six codons (UUA, UUG, CUU, CUC, CUA, and CUG) and is a major component of the subunits in ferritin, astacin and other ‘buffer’ proteins. 2. Inborn errors of the metabolism Branched-chain organic acidurias are inborn errors of the metabolism involving the branched-chain amino acids (BCAAs) leucine, isoleucine and valine. These diseases usually involve neurological symptoms. They are treatable with strictly controlled diets and enhancement of detoxification of toxic intermediate metabolites. Detoxification is enhanced through supplementation of glycine, carnitine, biotin and other vitamins where applicable. The most common branched-chain organic acidurias are maple syrup urine disease (MSUD), 3-methylcrotonyl-CoA carboxylase (MCC), propionic aciduria (PCC), methylmalonic aciduria (MMA) and isovaleric aciduria (IVA) deficiency (Heidelberg, 2012). Leucine is involved in a few inborn errors of the metabolism, from which maple syrup urine disease (MSUD) is one of the ma in mentioned. MSUD is caused by a deficiency in the branched-chain alpha-keto acid dehydrogenase complex. (Lanpher, 2006) Ketoacidosis, neurological disorders, and developmental disturbance can all be induced by the accumulations of branched-chain amino acids (BCAAs) and branched-chain alpha-keto-acids (BCKAs) in patients with MSUD. According to clinical investigations on MSUD patients, leucine levels over 400ÃŽ ¼mol/L apparently can cause any clinical problem derived from impaired function of the central nervous system. Damage to neuronal cells found in MSUD patients are presumably because of higher concentrations of both blood BCAAs or BCKAs, especially alpha-keto-isocapronic acids. These clinical data from MSUD patients provide a valuable basis on understanding leucine toxicity in the normal subject. (Fromm & Hargrove, 2012)