Biomolecules

Nucleic acids are biological molecules essential for life and include DNA (deoxyribonucleic acid) and RNA (ribonucleic acid). Together with proteins, nucleic acids make up the most important macromolecules; each is found in abundance in all living things. Nucleic acids were first discovered by Friedrich Miescher in 1871.

Nucleic acids are linear polymers (chains) of nucleotides. Each nucleotide consists of three components: a purine or pyrimidine nucleobase (sometimes termed nitrogenous base or simply base), a pentose sugar; and a phosphate group. The sugars and phosphates in nucleic acids are connected to each other in an alternating chain (sugar-phosphate backbone) through phosphodiester linkages.

Sphingolipids are a class of lipids derived from the aliphatic amino alcohol sphingosine. These compounds play important roles in signal transmission and cell recognition. Sphingolipidoses, or disorders of sphingolipid metabolism, have particular impact on neural tissue.

Monosaccharides are the most basic units of biologically important carbohydrates. These are the simplest form of sugar and are usually colourless, water-soluble, crystalline solids. Some monosaccharides have a sweet taste. Examples of monosaccharides include glucose (dextrose), fructose (levulose), galactose, xylose and ribose.

Fructose, or fruit sugar, is a simple monosaccharide found in many foods. It is one of the three important dietary monosaccharides along with glucose and galactose.

Glycosylation is the enzymatic process that attaches glycans to proteins, lipids, or other organic molecules. This enzymatic process produces one of the fundamental biopolymers found in cells (along with DNA, RNA, and proteins). Glycosylation is a form of co-translational and post-translational modification.

Saccharolipids describe compounds in which fatty acids are linked directly to a sugar backbone, forming structures that are compatible with membrane bilayers. In the saccharolipids, a monosaccharide substitutes for the glycerol backbone present in glycerolipids and glycerophospholipids.

Lipids are fats, including oils. Their structures include a membrane around the cells, which prevents them from mixing with water. Lipids include fatty acids; triglycerides, which is what most people think of as dietary fat; phospholipids, which are fats attached to a phosphate; and cholesterol, which produces steroids. Lipids are capable of expanding in shape or size.

Galactose is a monosaccharide. When combined with glucose, through a dehydration reaction, the result is the disaccharide lactose. The hydrolysis of lactose to glucose and galactose is catalyzed by the enzyme lactase and β-galactosidase. This enzyme is produced by the lac operon in Escherichia coli.

In proteins, the secondary structure is defined by the patterns of hydrogen bonds between backbone amide and carboxyl groups. The hydrogen bonding patterns may be significantly distorted, which makes an automatic determination of secondary structure difficult.

Monosaccharides are the building blocks of disaccharides such as sucrose and polysaccharides (such as cellulose and starch). Further, each carbon atom that supports a hydroxyl group (except for the first and last) is chiral, giving rise to a number of isomeric forms all with the same chemical formula. For instance, galactose and glucose are both aldohexoses, but have different chemical and physical properties.

Vitamin B6 also plays a role in gluconeogenesis. Pyridoxal phosphate can catalyze transamination reactions that are essential for the providing amino acids as a substrate for gluconeogenesis.

Benfotiamine is a synthetic S-acyl derivative of thiamine (vitamin B1). After absorption, benfotiamine can be dephosphorylated by cells bearing an ecto-alkaline phosphatase to the lipid-soluble S-benzoylthiamine.

An all-β proteins is a class of structural domains in which the secondary structure is composed entirely of β-sheets, with the possible exception of a few isolated α-helices on the periphery. Common examples include the SH3 domain, the beta-propeller domain, the immunoglobulin fold and B3 DNA binding domain.

Fursultiamine is a disulfide derivative of thiamine, or an allithiamine . It has also been investigated in improving energy metabolism during exercise and reducing exercise-induced fatigue with conflicting results.

Propionyl-CoA carboxylase catalyses the carboxylation reaction of propionyl CoA in the mitochondrial matrix. The enzyme is biotin dependent. The product of the reaction is (S)-methylmalonyl CoA. Propionyl CoA is the end product of metabolism of odd-chain fatty acids and is also a metabolite of most methyl-branched fatty acids.

Folic acid is a form of the water-soluble vitamin B9. Folic acid is itself not biologically active, but its biological importance is due to tetrahydrofolate and other derivatives after its conversion to dihydrofolic acid in the liver.

Panthenol is the alcohol analog of pantothenic acid (vitamin B₅), and is thus a provitamin of B₅. Panthenol is a highly viscous transparent liquid at room temperature. It is soluble in water, alcohol and propylene glycol, soluble in ether and chloroform, and slightly soluble in glycerin.

Pyridoxine assists in the balancing of sodium and potassium as well as promoting red blood cell production. It is linked to cardiovascular health by decreasing the formation of homocysteine. Pyridoxine may help balance hormonal changes in women and aid the immune system. Lack of pyridoxine may cause anemia, nerve damage, seizures, skin problems and sores in the mouth.

Riboflavin, also known as vitamin B₂ or additive E101, is an easily absorbed micronutrient with a key role in maintaining health in humans and animals. It is the central component of the cofactors FAD and FMN, and is, therefore, required by all flavoproteins. As such, vitamin B₂ is required for a wide variety of cellular processes. It plays a key role in energy metabolism, and for the metabolism of fats, ketone bodies, carbohydrates and proteins.

Ascorbic acid is a naturally occurring organic compound with antioxidant properties. It is a white solid but impure samples can appear yellowish. It dissolves well in water to give mildly acidic solutions. Ascorbic acid is one form (vitamer) of vitamin C.

7-Dehydrocholesterol is a zoosterol that functions in the serum as a cholesterol precursor, and is converted to vitamin D₃ in the skin.The presence of this compound in human skin enables humans to manufacture vitamin D₃ from ultra-violet rays in the sun light, via an intermediate isomer pre-vitamin D₃. It is also found in the milk of several mammalian species.

Calcitroic acid (1α-hydroxy-23-carboxy-24,25,26,27-tetranorvitamin D3) is a metabolite of 1α,25-dihydroxyvitamin D3 (calcitriol). Its formation is catalyzed by the enzyme calcitriol 24-hydroxylase. Calcitroic acid is soluble in water and excreted in urine.

Vitamin C is an essential nutrient for humans and certain other animal species. In living organisms ascorbate acts as an antioxidant by protecting the body against oxidative stress.It is also a cofactor in at least eight enzymatic reactions including several collagen synthesis reactions that cause the most severe symptoms of scurvy when these are dysfunctional.

Also referred to as ascorbic acid. Functioning as an excellent antioxidant, it has the ability to prevent the harmful oxidation of cells.