CHEMISTRY GLOSSARY

isoleucine    →   izoleucin

Isoleucine is hydrophobic amino acids with aliphatic side chain. It is one of the three amino acids having branched hydrocarbon side chains. The side chains of these amino acids are not reactive but, these residues are critically important for ligand binding to proteins, and play central roles in protein stability. Isoleucine is an essential amino acid, which means that humans cannot synthesize it, so it must be ingested.

• Abbreviations: Ile, I
• IUPAC name: 2-amino-3-methylpentanoic acid
• Molecular formula: C₆H₁₃NO₂
• Molecular weight: 131.12 g/mol

leucine    →   leucin

Leucine is hydrophobic amino acids with aliphatic side chain. It has one additional methylene group in its side chain compared with valine. The nonpolar hydrophobic amino acids tend to cluster together within proteins, stabilizing protein structure by means of hydrophobic interactions. Leucine is an essential amino acid, which means that humans cannot synthesize it, so it must be ingested.

• Abbreviations: Leu, L
• IUPAC name: 2-amino-4-methylpentanoic acid
• Molecular formula: C₆H₁₃NO₂
• Molecular weight: 131.17 g/mol

methionine    →   metionin

Methionine is neutral amino acids with polar side chains. It is one of the two sulfur-containing amino acids. Methionine is a fairly hydrophobic amino acid and typically found buried within the interior of a protein. It can form stacking interactions with the aromatic moieties of tryptophan, phenylalanine, and tyrosine. It is an essential amino acid, which means that humans cannot synthesize it, so it must be ingested.

• Abbreviations: Met, M
• IUPAC name: 2-amino-4-methylsulfanylbutanoic acid
• Molecular formula: C₅H₁₁NO₂S
• Molecular weight: 149.21 g/mol

nerve poison    →   živčani bojni otrov

Nerve poison (nerve gas, agents) have had an entirely dominant role since the Second World War. Nerve poisons acquired their name because they affect the transmission of nerve impulses in the nervous system. All nerve poisons belong chemically to the group of organo-phosphorus compounds. They are stable and easily dispersed, highly toxic and have rapid effects both when absorbed through the skin and via respiration. Nerve poisons can be manufactured by means of fairly simple chemical techniques. The raw materials are inexpensive and generally readily available.

The most important nerve agents included in modern chemical weapons arsenals are:

Nerve poisons are colorless, odorless, tasteless liquids of low volatility. Antidotes are atropine sulfate and pralidoxime iodide.

omega-3 fatty acids    →   omega-3 masne kiseline

Omega-3 fatty acids are polyunsaturated fatty acids, meaning they contain more than one double bond. The name omega-3 indicates that the first double bond occurs on the third carbon atom (n-3) from the methyl (-CH₃) end of the molecule (omega position). The three main omega-3 fatty acids are alpha-linolenic acid (ALA, 18:3n-3), eicosapentaenoic acid (EPA, 20:5n-3), and docosahexaenoic acid (DHA, 22:6n-3). ALA comes from plants. EPA and DHA come from fish.

Similarly, the first double bond in omega-6 fatty acids is located between the sixth and seventh carbon atom (n-6) from the methyl end of the fatty acid (omega end).

ribonucleic acid    →   ribonukleinska kiselina

Ribonucleic acid is a complex organic compound in living cells that is concerned with protein synthesis. Plays an intermediary role in converting the information contained in DNA into proteins. RNA carries the genetic information from DNA to those parts of the cell where proteins are made. Some viruses store their genetic information as RNA not as DNA.

Ribonucleic acid is a similar molecule to DNA but with a slightly different structure.

The structural difference with DNA is that RNA contains a -OH group both at the 2' and 3' position of the ribose ring, whereas DNA (which stands, in fact, for deoxy-RNA) lacks such a hydroxy group at the 2' position of the ribose. The same bases can be attached to the ribose group in RNA as occur in DNA, with the exception that in RNA thymine does not occur, and is replaced by uracil, which has an H-group instead of a methyl group at the C-5 position of the pyrimidine. Unlike the double-stranded DNA molecule, RNA is a single-stranded molecule.

The three main functionally distinct varieties of RNA molecules are: (1) messenger RNA (mRNA) which is involved in the transmission of DNA information, (2) ribosomal RNa (rRNA) which makes up the physical machinery of the synthetic process, and (3) transfer RNA (tRNA) which also constitutes another functional part of the machinery of protein synthesis.

threonine    →   treonin

Threonine is neutral amino acids with polar side chains. It differs from serine by having a methyl substituent in place of one of the hydrogens on the β carbon. Threonine is a site of phosphorylation and glycosylation which is important for enzyme regulation and cell signaling. It is an essential amino acid, which means that humans cannot synthesize it, so it must be ingested.

• Abbreviations: Thr, T
• IUPAC name: 2-amino-3-hydroxybutanoic acid
• Molecular formula: C₄H₉NO₃
• Molecular weight: 119.12 g/mol

valine    →   valin

Valine is hydrophobic amino acids with aliphatic side chain. It is a member of the branched-chain amino acid family, along with leucine and isoleucine. Valine differs from threonine by replacement of the hydroxyl group with a methyl substituent, but they are of roughly the same shape and volume. The nonpolar hydrophobic amino acids tend to cluster together within proteins, stabilizing protein structure by means of hydrophobic interactions. Valine is an essential amino acid, which means that it cannot be synthesized in the body and must be obtained through dietary sources.

• Abbreviations: Val, V
• IUPAC name: 2-amino-3-methylbutanoic acid
• Molecular formula: C₅H₁₁NO₂
• Molecular weight: 117.15 g/mol