Human beta-defensin 104A (DEFB104A) is an antimicrobial peptide that contributes to both the innate and the adaptive immune systems and is active against gram-negative and gram-positive bacteria, fungi, and viruses. Like the other β-defensins, DEFB104A is a small protein that contains a motif consisting of six cysteine residues which form three intramolecular disulfide bridges. It is expressed at highest levels in the testis and stomach, and at lower levels in the uterus, neutrophils, thyroid, lung, and kidney. Expression of DEFB104A is upregulated by phorbol 12-myristate 13-acetate (PMA), as well as in response to infection with gram-positive and gram-negative bacteria. DEFB104A is a cationic peptide and interacts with the membranes of invading microbes, which are negatively charged due to the presence of lipopolysaccharides (LPS) or lipoteichoic acid (LTA). LTA and LPS have higher affinity for DEFB103A than for Ca+2 and Mg+2 ions. The larger defensin molecule displaces the smaller ion, changing the membrane structure and affecting the stability of the membrane; this can lead to the formation of pores and subsequent depolarization or lysis. DEFB104A has been shown to be more active against Pseudomonas aeruginosa than DEFB1, DEFB4A, or DEFB103A. Inhibition of DEFB104A by high salt concentration may play a role in the pathogenesis of cystic fibrosis.

Murine beta-defensin 2 (DEFB2) is an antimicrobial peptide that contributes to the innate immune system and is active against gram-negative bacteria, fungi, and viruses. It also contributes to the adaptive immune system through recruitment of leukocytes to sites of infection through chemotaxis. Like the other β-defensins, DEFB2 is a small protein that contains a motif consisting of six cysteine residues which form three intramolecular disulfide bridges. It is expressed in the epithelia of skin and organs in the genitourinary tract, as well as in monocytes and macrophages. Expression is induced by 1,25-dihydroxyvitamin D3, LPS, and proinflammatory cytokines, such as IL1B and IFNG, and downregulated by the anti-inflammatory steroid dexamethasone. DEFB2 expression is also induced by exposure to low M.W. hyaluronic acid fragments, which is common following inflammation or tissue injury. DEFB2 is a cationic peptide that disrupts the membranes of invading microbes, which are negatively charged due to the presence of lipopolysaccharides (LPS) or lipoteichoic acid (LTA). In mice that have had the Defb2 gene silenced, inducible NO synthase expression was elevated. DEFB2 works in combination with DEFB3 to contribute to resistance against corneal infection. Inhibition of DEFB2 by high salt concentration may play a role in the pathogenesis of cystic fibrosis.

Murine beta-defensin 3 (DEFB3) is an antimicrobial peptide that contributes to the innate and adaptive immune systems and is active against gram-negative and gram-positive bacteria, fungi, and viruses. Like the other β-defensins, DEFB3 is a small protein that contains a motif consisting of six cysteine residues which form three intramolecular disulfide bridges. It is expressed in epithelial tissue of many organs, including the skin and lungs, and in leukocytes. Expression of DEFB3 is induced by proinflammatory cytokines such as IL1B and IFNG. Expression of murine DEFB3 was found to be downregulated in the epidermis by psychological stress due to decreased glucocorticoid production and subsequent decreased defensin-encapsulating lamellar body secretion. DEFB3 is a cationic peptide and interacts with the membranes of invading microbes, which are negatively charged due to the presence of lipopolysaccharides (LPS) or lipoteichoic acid (LTA). LTA and LPS have higher affinity for DEFB3 than for Ca+2 and Mg+2 ions. The larger defensin molecule displaces the smaller ion, changing the membrane structure and affecting the stability of the membrane; this can lead to the formation of pores and subsequent depolarization or lysis. Inhibition of DEFB3 by high salt concentration may play a role in the pathogenesis of cystic fibrosis.

Rat beta-defensin 3 (DEFB3) is an antimicrobial peptide that contributes to the innate and adaptive immune systems and is active against gram-negative and gram-positive bacteria, fungi, and viruses. Like the other β-defensins, DEFB3 is a small protein that contains a motif consisting of six cysteine residues which form three intramolecular disulfide bridges. It is expressed in epithelial tissue of many organs, including the skin and lungs, and in leukocytes. Expression of DEFB3 is induced by proinflammatory cytokines such as IL1B and IFNG. Expression of rat DEFB3 was also found to be induced in bronchoalveolar lavage fluid by inflammatory diesel exhaust particles. DEFB3 is a cationic peptide that disrupts the membranes of invading microbes, which are negatively charged due to the presence of lipopolysaccharides (LPS) or lipoteichoic acid (LTA). Inhibition of DEFB3 by high salt concentration may play a role in the pathogenesis of cystic fibrosis.

Rat beta-defensin 4 (DEFB4) is an antimicrobial peptide that contributes to the innate immune system and is active against gram-negative bacteria, fungi, and viruses. It also contributes to the adaptive immune system through recruitment of leukocytes to sites of infection through chemotaxis. Like the other β-defensins, DEFB4 is a small protein that contains a motif consisting of six cysteine residues which form three intramolecular disulfide bridges. It is expressed in epithelia of many organs, including the lung and skin, as well as in monocytes and macrophages. Expression is induced by proinflammatory cytokines, such as IL1B and IFNG. DEFB4 is a cationic peptide that disrupts the membranes of invading microbes, which are negatively charged due to the presence of lipopolysaccharides (LPS) or lipoteichoic acid (LTA). DEFB4 stimulates mast cells to induce Ca2+ mobilization, histamine release, and COX-1 mediated prostaglandin D2 release in a G-protein-dependent and phospholipase C-dependent manner. DEFB4 also stimulates cholinergic Ca2+-dependent epithelial Cl- secretion. Inhibition of DEFB4 by high salt concentration may play a role in the pathogenesis of cystic fibrosis.

Human beta-defensin 4A (DEFB4A) is an antimicrobial peptide that contributes to the innate immune system and is active against gram-negative bacteria, fungi, and viruses. It also contributes to the adaptive immune system through recruitment of leukocytes to sites of infection through chemotaxis. Like the other β-defensins, DEFB4A is a small protein that contains a motif consisting of six cysteine residues which form three intramolecular disulfide bridges. It is expressed in epithelia of many organs, including the lungs and skin, as well as in monocytes and macrophages. Expression is induced by 1,25-dihydroxyvitamin D3 and proinflammatory cytokines, such as IL1B and IFNG, and downregulated by the anti-inflammatory steroid dexamethasone. DEFB4A is a cationic peptide that disrupts the membranes of invading microbes, which are negatively charged due to the presence of lipopolysaccharides (LPS) or lipoteichoic acid (LTA). DEFB4A stimulates mast cells to induce Ca2+ mobilization, histamine release, and COX-1 mediated prostaglandin D2 release in a G-protein-dependent and phospholipase C-dependent manner. Inhibition of DEFB4A by high salt concentration may play a role in the pathogenesis of cystic fibrosis.

Dehydroascorbic acid or oxidized vitamin C has dietary and cosmetic applications. It is actively brought into the endoplasmic reticulum of cells through glucose transport and generates oxidative potential. Dehydroascorbic acid is the oxidized form of vitamin C.

Deoxycholic acid (typically abbreviated DOC) is a bile acid typically found in the intestine. Bile acids typically cause DNA damage and can lead to an increase in mutations. Deoxycholic acid can be covalently attached to glycol chitosan as a delivery system in nanotechnological applications. Many other applications, such as those to perform 1,4-addition of diethylzinc to acyclic enones, requires the binding of Deoxycholic acid to other molecules to create ligands that are conducive to addition of metals to certain enones.

In more general applications, Deoxycholic acid is used to increase the solubilization of cells. Deoxycholic acid is typically used as an ingredient in the creation of RIPA buffers, added in concentrations between 0.5% and 2.5%. These buffers are typically used to extract proteins from membranes and cytoplasm. This method of extraction contains the ionic detergent SDS and is useful for the disruption of nuclear membranes and their associated proteins. Proteins extracted via this initial procedure can be used in other analytical procedures like western blot or a BCA protein assay.

Deoxyribonucleic acid, sodium salt from Salmon Sperm is a nonspecific DNA blocking agent used to reduce background in nucleic acid hybridization. Additionally, it has been used to develop a method used to extract DNA from Cryptosporidium oocysts. It may be used as a substrate for the development of DNA detection methods.