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In chemistry, residue is whatever remains or acts as a contaminant after a given class of events. Residue may be the material remaining after a process of preparation, separation, or purification, such as distillation, evaporation, or filtration. It may also denote the undesired by-products of a chemical reaction.
Residues as an undesired by-product are a concern in agricultural and food industries.
Toxic chemical residues, wastes or contamination from other processes, are a concern in food safety. The most common food residues originate from pesticides, veterinary drugs, and industrial chemicals. [1] For example, the U.S. Food and Drug Administration (FDA) and the Canadian Food Inspection Agency (CFIA) have guidelines for detecting chemical residues that are possibly dangerous to consume. [2] [3] In the U.S., the FDA is responsible for setting guidelines while other organizations enforce them.
Similar to the food industry, in environmental sciences residue also refers to chemical contaminants. Residues in the environment are often the result of industrial processes, such as escaped chemicals from mining processing, fuel leaks during industrial transportation, trace amounts of radioactive material, and excess pesticides that enter the soil. [4]
Residue may refer to an atom or a group of atoms that form part of a molecule, such as a methyl group.
In biochemistry and molecular biology, a residue refers to a specific monomer within the polymeric chain of a polysaccharide, protein or nucleic acid.
In proteins, the carboxyl group of one amino acid links with the amino group of another amino acid to form a peptide. This results in the removal of water and what remains is called the residue. Naming of residues is done by replacing "acid" with "residue". [5] A residue's properties will influence interactions with other residues and the overall chemical properties of the protein it resides in. One might say, "This protein consists of 118 amino acid residues" or "The histidine residue is considered to be basic because it contains an imidazole ring." Note that a residue is different from a moiety, which, in the above example would be constituted by the imidazole ring or the imidazole moiety.
Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although over 500 amino acids exist in nature, by far the most important are the 22 α-amino acids incorporated into proteins. Only these 22 appear in the genetic code of life.
Biochemistry or biological chemistry is the study of chemical processes within and relating to living organisms. A sub-discipline of both chemistry and biology, biochemistry may be divided into three fields: structural biology, enzymology, and metabolism. Over the last decades of the 20th century, biochemistry has become successful at explaining living processes through these three disciplines. Almost all areas of the life sciences are being uncovered and developed through biochemical methodology and research. Biochemistry focuses on understanding the chemical basis which allows biological molecules to give rise to the processes that occur within living cells and between cells, in turn relating greatly to the understanding of tissues and organs as well as organism structure and function. Biochemistry is closely related to molecular biology, the study of the molecular mechanisms of biological phenomena.
Chymotrypsin (EC 3.4.21.1, chymotrypsins A and B, alpha-chymar ophth, avazyme, chymar, chymotest, enzeon, quimar, quimotrase, alpha-chymar, alpha-chymotrypsin A, alpha-chymotrypsin) is a digestive enzyme component of pancreatic juice acting in the duodenum, where it performs proteolysis, the breakdown of proteins and polypeptides. Chymotrypsin preferentially cleaves peptide amide bonds where the side chain of the amino acid N-terminal to the scissile amide bond (the P1 position) is a large hydrophobic amino acid (tyrosine, tryptophan, and phenylalanine). These amino acids contain an aromatic ring in their side chain that fits into a hydrophobic pocket (the S1 position) of the enzyme. It is activated in the presence of trypsin. The hydrophobic and shape complementarity between the peptide substrate P1 side chain and the enzyme S1 binding cavity accounts for the substrate specificity of this enzyme. Chymotrypsin also hydrolyzes other amide bonds in peptides at slower rates, particularly those containing leucine at the P1 position.
In organic chemistry, a peptide bond is an amide type of covalent chemical bond linking two consecutive alpha-amino acids from C1 of one alpha-amino acid and N2 of another, along a peptide or protein chain.
Protein primary structure is the linear sequence of amino acids in a peptide or protein. By convention, the primary structure of a protein is reported starting from the amino-terminal (N) end to the carboxyl-terminal (C) end. Protein biosynthesis is most commonly performed by ribosomes in cells. Peptides can also be synthesized in the laboratory. Protein primary structures can be directly sequenced, or inferred from DNA sequences.
Flavins refers generally to the class of organic compounds containing the tricyclic heterocycle isoalloxazine or its isomer alloxazine, and derivatives thereof. The biochemical source of flavin is the yellow B vitamin riboflavin. The flavin moiety is often attached with an adenosine diphosphate to form flavin adenine dinucleotide (FAD), and, in other circumstances, is found as flavin mononucleotide, a phosphorylated form of riboflavin. It is in one or the other of these forms that flavin is present as a prosthetic group in flavoproteins. Despite the similar names, flavins are chemically and biologically distinct from the flavanoids, and the flavonols.
In molecular biology, post-translational modification (PTM) is the covalent process of changing proteins following protein biosynthesis. PTMs may involve enzymes or occur spontaneously. Proteins are created by ribosomes, which translate mRNA into polypeptide chains, which may then change to form the mature protein product. PTMs are important components in cell signalling, as for example when prohormones are converted to hormones.
Chelation is a type of bonding of ions and their molecules to metal ions. It involves the formation or presence of two or more separate coordinate bonds between a polydentate ligand and a single central metal atom. These ligands are called chelants, chelators, chelating agents, or sequestering agents. They are usually organic compounds, but this is not a necessity.
Melamine is an organic compound with the formula C3H6N6. This white solid is a trimer of cyanamide, with a 1,3,5-triazine skeleton. Like cyanamide, it contains 66% nitrogen by mass, and its derivatives have fire-retardant properties due to its release of nitrogen gas when burned or charred. Melamine can be combined with formaldehyde and other agents to produce melamine resins. Such resins are characteristically durable thermosetting plastic used in high pressure decorative laminates such as Formica, melamine dinnerware including cooking utensils, plates, plastic products, laminate flooring, and dry erase boards. Melamine foam is used as insulation, soundproofing material and in polymeric cleaning products, such as Magic Eraser.
In organic chemistry, a carbamate is a category of organic compounds with the general formula R2NC(O)OR and structure >N−C(=O)−O−, which are formally derived from carbamic acid. The term includes organic compounds, formally obtained by replacing one or more of the hydrogen atoms by other organic functional groups; as well as salts with the carbamate anion H2NCOO−.
In organic chemistry, peptide synthesis is the production of peptides, compounds where multiple amino acids are linked via amide bonds, also known as peptide bonds. Peptides are chemically synthesized by the condensation reaction of the carboxyl group of one amino acid to the amino group of another. Protecting group strategies are usually necessary to prevent undesirable side reactions with the various amino acid side chains. Chemical peptide synthesis most commonly starts at the carboxyl end of the peptide (C-terminus), and proceeds toward the amino-terminus (N-terminus). Protein biosynthesis in living organisms occurs in the opposite direction.
Pesticide residue refers to the pesticides that may remain on or in food, after they are applied to food crops. The maximum allowable levels of these residues in foods are stipulated by regulatory bodies in many countries. Regulations such as pre-harvest intervals also prevent harvest of crop or livestock products if recently treated in order to allow residue concentrations to decrease over time to safe levels before harvest.
The Principles of Good Laboratory Practice (GLP) establish rules and criteria for a quality system that oversees the organizational processes and conditions in which non-clinical health and environmental safety studies are planned, conducted, monitored, recorded, reported, and archived. These principles apply to the non-clinical safety testing of substances found in various products to ensure the quality and integrity of the safety data submitted to regulatory authorities globally.
In chemistry, fine chemicals are complex, single, pure chemical substances, produced in limited quantities in multipurpose plants by multistep batch chemical or biotechnological processes. They are described by exacting specifications, used for further processing within the chemical industry and sold for more than $10/kg. The class of fine chemicals is subdivided either on the basis of the added value, or the type of business transaction, namely standard or exclusive products.
Heterocyclic amines, also sometimes referred to as HCAs, are chemical compounds containing at least one heterocyclic ring, which by definition has atoms of at least two different elements, as well as at least one amine (nitrogen-containing) group. Typically it is a nitrogen atom of an amine group that also makes the ring heterocyclic, though compounds exist in which this is not the case. The biological functions of heterocyclic amines vary, including vitamins and carcinogens. Carcinogenic heterocyclic amines are created by high temperature cooking of meat and smoking of plant matter like tobacco. Some well known heterocyclic amines are niacin, nicotine, and the nucleobases that encode genetic information in DNA.
Neurokinin 1 (NK1) antagonists (-pitants) are a novel class of medications that possesses unique antidepressant, anxiolytic, and antiemetic properties. NK-1 antagonists boost the efficacy of 5-HT3 antagonists to prevent nausea and vomiting. The discovery of neurokinin 1 (NK1) receptor antagonists was a turning point in the prevention of nausea and vomiting associated with cancer chemotherapy.
Ovotransferrin (conalbumin) is a glycoprotein of egg white albumen. Egg white albumen is composed of multiple proteins, of which ovotransferrin is the most heat reliable. It has a molecular weight of 76,000 daltons and contains about 700 amino acids. Ovotransferrin makes up approximately 13% of egg albumen. As a member of the transferrin and metalloproteinase family, ovotransferrin has been found to possess antibacterial and antioxydant and immunomodulatory properties, arising primarily through its iron (Fe3+) binding capacity by locking away a key biochemical component necessary for micro-organismal survival. Bacteria starved of iron are rendered incapable of moving, making ovotransferrin a potent bacteriostatic.
In China, the adulteration and contamination of several food and feed ingredients with inexpensive melamine and other compounds, such as cyanuric acid, ammeline and ammelide, are common practice. These adulterants can be used to inflate the apparent protein content of products, so that inexpensive ingredients can pass for more expensive, concentrated proteins. Melamine by itself has not been thought to be very toxic to animals or humans except possibly in very high concentrations, but the combination of melamine and cyanuric acid has been implicated in kidney failure. Reports that cyanuric acid may be an independently and potentially widely used adulterant in China have heightened concerns for both animal and human health.
The angiotensin receptor blockers (ARBs), also called angiotensin (AT1) receptor antagonists or sartans, are a group of antihypertensive drugs that act by blocking the effects of the hormone angiotensin II in the body, thereby lowering blood pressure. Their structure is similar to Ang II and they bind to Ang II receptors as inhibitors, e.g., [T24 from Rhys Healthcare].
Dietary exposure assessments in the United States involve the evaluation of dietary consumption and chemical residue data while taking into consideration additional factors that may affect a specified population of interest or sensitive population. The process of conducting a dietary exposure assessment involves the determination of the chemical residues on a particular food or foods and the calculation of the dietary exposure to these chemicals based on consumption data for the specified food or foods. A dietary exposure assessment allows a comparison to a relevant health standard such as the acceptable daily intake (ADI), the acute reference dose.
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