Amino acids are organic compounds that contain amino and carboxylic acid functional groups, along with a side chain specific to each amino acid. The elements present in every amino acid are carbon (C), hydrogen (H), oxygen (O), and nitrogen (N) (CHON); in addition sulfur (S) is present in the side chains of cysteine and methionine, and selenium (Se) in the less common amino acid selenocysteine. More than 500 naturally occurring amino acids are known to constitute monomer units of peptides, including proteins, as of 2020 although only 22 appear in the genetic code, 20 of which have their own designated codons and 2 of which have special coding mechanisms: Selenocysteine which is present in all eukaryotes and pyrrolysine which is present in some prokaryotes.
The genetic code is the set of rules used by living cells to translate information encoded within genetic material into proteins. Translation is accomplished by the ribosome, which links proteinogenic amino acids in an order specified by messenger RNA (mRNA), using transfer RNA (tRNA) molecules to carry amino acids and to read the mRNA three nucleotides at a time. The genetic code is highly similar among all organisms and can be expressed in a simple table with 64 entries.
Proteinoids, or thermal proteins, are protein-like, often cross-linked molecules formed abiotically from amino acids. Sidney W. Fox initially proposed that they may have been precursors to the first living cells (protocells). The term was also used in the 1960s to describe peptides that are shorter than twenty amino acids found in hydrolysed protein, but this term is no longer commonly used.
Alanine (symbol Ala or A), or α-alanine, is an α-amino acid that is used in the biosynthesis of proteins. It contains an amine group and a carboxylic acid group, both attached to the central carbon atom which also carries a methyl group side chain. Consequently, its IUPAC systematic name is 2-aminopropanoic acid, and it is classified as a nonpolar, aliphatic α-amino acid. Under biological conditions, it exists in its zwitterionic form with its amine group protonated (as −NH3+) and its carboxyl group deprotonated (as −CO2−). It is non-essential to humans as it can be synthesised metabolically and does not need to be present in the diet. It is encoded by all codons starting with GC (GCU, GCC, GCA, and GCG).
Biochemistry is the study of the chemical processes in living organisms. It deals with the structure and function of cellular components such as proteins, carbohydrates, lipids, nucleic acids and other biomolecules.
Proteinogenic amino acids are amino acids that are incorporated biosynthetically into proteins during translation. The word "proteinogenic" means "protein creating". Throughout known life, there are 22 genetically encoded (proteinogenic) amino acids, 20 in the standard genetic code and an additional 2 that can be incorporated by special translation mechanisms.
In molecular biology, elastase is an enzyme from the class of proteases (peptidases) that break down proteins. In particular, it is a serine protease.
Amino acid synthesis is the set of biochemical processes by which the amino acids are produced. The substrates for these processes are various compounds in the organism's diet or growth media. Not all organisms are able to synthesize all amino acids. For example, humans can only synthesize 11 of the 20 standard amino acids, and in time of accelerated growth, histidine can be considered an essential amino acid.
Toxic shock syndrome toxin (TSST) is a superantigen with a size of 22 kDa produced by 5 to 25% of Staphylococcus aureus isolates. It causes toxic shock syndrome (TSS) by stimulating the release of large amounts of interleukin-1, interleukin-2 and tumour necrosis factor. In general, the toxin is not produced by bacteria growing in the blood; rather, it is produced at the local site of an infection, and then it enters the blood stream.
In biochemistry, non-coded or non-proteinogenic amino acids are distinct from the 22 proteinogenic amino acids which are naturally encoded in the genome of organisms for the assembly of proteins. However, over 140 non-proteinogenic amino acids occur naturally in proteins and thousands more may occur in nature or be synthesized in the laboratory. Many non-proteinogenic amino acids are important:
The yeast mitochondrial code is a genetic code used by the mitochondrial genome of yeasts, notably Saccharomyces cerevisiae, Candida glabrata, Hansenula saturnus, and Kluyveromyces thermotolerans.
Elastin-like polypeptides (ELPs) are synthetic biopolymers with potential applications in the fields of cancer therapy, tissue scaffolding, and protein purification. For cancer therapy, the addition of functional groups to ELPs can enable them to conjugate with cytotoxic drugs. Also, ELPs may be able to function as polymeric scaffolds, which promote tissue regeneration. This capacity of ELPs has been studied particularly in the context of bone growth. ELPs can also be engineered to recognize specific proteins in solution. The ability of ELPs to undergo morphological changes at certain temperatures enables specific proteins that are bound to the ELPs to be separated out from the rest of the solution via experimental techniques such as centrifugation.
The GNC hypothesis or GNC-SNS primeval genetic code hypothesis refers to a hypothesis about the origin of genes. It suggests the universal genetic code originated not from a three-amino acid system, but from a four-amino acid system. It is this GNC code encoding [GADV]-proteins which is the most primitive genetic code. This hypothesis was first proposed by Kenji Ikehara at Nara Women's University.
The echinoderm and flatworm mitochondrial code is a genetic code used by the mitochondria of certain echinoderm and flatworm species.
The ascidian mitochondrial code is a genetic code found in the mitochondria of Ascidia.
The trematode mitochondrial code is a genetic code found in the mitochondria of Trematoda.
Low complexity regions (LCRs) in protein sequences, also defined in some contexts as compositionally biased regions (CBRs), are regions in protein sequences that differ from the composition and complexity of most proteins that is normally associated with globular structure. LCRs have different properties from normal regions regarding structure, function and evolution.
LOC101928193 is a protein which in humans is encoded by the LOC101928193 gene. There are no known aliases for this gene or protein. Similar copies of this gene, called orthologs, are known to exist in several different species across mammals, amphibians, fish, mollusks, cnidarians, fungi, and bacteria. The human LOC101928193 gene is located on the long (q) arm of chromosome 9 with a cytogenic location at 9q34.2. The molecular location of the gene is from base pair 133,189,767 to base pair 133,192,979 on chromosome 9 for an mRNA length of 3213 nucleotides. The gene and protein are not yet well understood by the scientific community, but there is data on its genetic makeup and expression. The LOC101928193 protein is targeted for the cytoplasm and has the highest level of expression in the thyroid, ovary, skin, and testes in humans.
The QTY Code is a design method to transform membrane proteins that are intrinsically insoluble in water into variants with water solubility, while retaining their structure and function.
Phoratoxins are a group of peptide toxins that belong to the family of thionins, a subdivision of small plant toxins. Phoratoxins are proteins present in the leaves and branches of the Phoradendron, commonly known as the American variant of the mistletoe, a plant commonly used as decoration during the festive season. The berries of the mistletoe do not contain phoratoxins, making them less toxic compared to other parts of the plant. The toxicity of the mistletoe is dependent on the host tree, since mistletoe is known to be a semi-parasite. The host tree provides fixed inorganic nitrogen compounds necessary for the mistletoe to synthesize phoratoxins.
