Proline is one of the α-amino acids that are used by living organisms as the building blocks of proteins. Proline is unique among these in that the nitrogen atom is part of the ring structure, the cyclic array of carbon atoms, rather than outside the ring. That is, its amino group, through which it links to the other amino acids, is a secondary amine, rather than a primary amine group (−NH2), as in the other nineteen amino acids. The unique structure of proline, with the amino group part of the ring structure, is important for the shape of proteins. This configuration offers important properties to proteins since it is the carboxylic acid group (-COOH) that links one amino acid to the other. (A peptide bond is a chemical bond formed between two molecules when the carboxyl group of one molecule reacts with the amino group of the other molecule.) This unique aspect of proline is important in establishing the structure of the protein, contributing to various bends and kinks in the shape of the protein. For a protein to function, it must have a particular conformational shape [13, 14].
The benefits of Proline in the body is extensive, from being skin-deep, it penetrates deep into the bones. Its benefits pass through blood vessels, muscles and bones. It is responsible for the construction of human tissues such as skin, cartilage, ligaments, joints, tendons, bones and blood vessels, but even the veins, arteries and lymph vessels. With this nonessential amino acid, the muscles and joints are kept flexible. In addition, the collagen component is also important in maintaining strength of the heart muscle and helps repair damaged tissues and aids in any types of wound healing. In brewing, proteins rich in proline combine with polyphenols to produce haze (turbidity) [15].
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Figure 1.2: Structure of Proline 1.5 Properties of lysine
Lysine is an α-amino acid that is used in the biosynthesis of proteins. It contains an α- amino group (which is in the protonated −NH3+
form under biological conditions), an α- carboxylic acid group (which is in the deprotonated −COO− form under biological conditions), and a side chain (CH2)4NH2, classifying it as a charged (at physiological pH), aliphatic amino acid. It is essential in humans, meaning the body cannot synthesize it and thus it must be obtained from the diet. The amino group often participates in hydrogen bonding and as a general base in catalysis. The α-amino group (NH3+
) is attached to the fifth carbon from the α-carbon, which is attached to the carboxyl group. The side chain of lysine has three methylene groups, so that even though the terminal amino group will be charged under physiological conditions, the side chain does have significant hydrophobic character. Lysine is often found buried with only the amino group exposed to solvent [16].
It is the building blocks of protein. Lysine is important for proper growth, and it plays an essential role in the production of carnitine, a nutrient responsible for converting fatty acids into energy and helping lower cholesterol. Lysine appears to help the body absorb calcium, and it plays an important role in the formation of collagen, a substance important for bones and connective tissues including skin, tendons, and cartilage [17].
Deficiency of L-lysine may lead to anemia, blood shoot eyes, enzyme problems, hair loss, inability to concentrate, irritability, lack of energy, poor appetite, reproductive problems, retarded growth and weight loss. Lysine has been studied for the prevention and treatment of herpes infections and cold sores. It also increases the intestinal absorption of calcium and eliminates its excretion by the kidney, suggesting that it might be helpful in osteoporosis. Lysine has been investigated for its effects on increasing muscle mass, lowering glucose, and improving anxiety. Case reports suggest lysine may ameliorate
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angina. Lysine acetylsalicylate has been used to treat pain and to detoxify the body after heroin use. Lysine clonixinate has been used to treat migraine headaches and other painful conditions [18].
Figure 1.3: Structure of Lysine 1.6 Properties of nicotinamide
Nicotinamide is the amide form of vitamin B3 (niacin) and is obtained through synthesis in the body or as a dietary source and supplement [19]. It is water soluble vitamin. The molecular formula of nicotinamide is C6H6N2O. Chemical name is3-Pyridinecarboxamide.
Nicotinamide is subsequently generated through the conversion of nicotinic acid in the liver or through the hydrolysis of NAD+. Once nicotinamide is obtained in the body, it functions as the precursor for the coenzyme β-nicotinamide adenine dinucleotide (NAD+) [20,21] and also is essential for the synthesis of nicotinamide adenine dinucleotide phosphate (NADP+) [22]. These cellular pathways are essential for energy metabolism and may directly impact normal physiology, as well as disease progression [23,24]. It may play a role in preventing type-I diabetes and some cancers. Nicotinamide has an anti- inflammatory effect which is helpful in the treatment of acne. It is also used for leprosy, memory loss, arthritis, improving digestion and lowering blood pressure. The mode of interactions of aqueous solution of nicotinamide and amino acids are of vital importance in the field of solution chemistry and pharmaceutical industry as it can provide with important information regarding hydrophilic and hydrophobic interactions.
Figure 1.4: Structure of nicotinamide
7 1.7 Properties of water
Water has a very simple molecular structure. The nature of the molecular structure of water causes its molecules to have unique electrochemical properties. The hydrogen side of the water molecule has a slight positive charge. On the other side of the molecule a negative charge exists. This molecular polarity causes water to be a powerful solvent and is responsible for its strong surface tension.
When the water molecule makes a physical phase change its molecules arrange themselves in distinctly different patterns. The molecular arrangement taken by ice (the solid form of the water molecule) leads to an increase in volume and a decrease in density. Expansion of the water molecule at freezing allows ice to float on top of liquid water.