Category: S

  • Superantigens

    Certain types of antigens that activate a large proportion of an organism’s immune system T cells. These superantigens, which thus over-activate the organism’s immune system, are thought to be responsible for some autoimmune diseases (in which T cells attack and destroy the organism’s own, healthy tissues). An antigen that binds with class 1 major histocompatibility…

  • Sudden death syndrome

    A disease that sometimes afflicts soybean plants.  

  • Substrate (structural)

    The substance (support) to which the agent of interest (a molecule) is attached. For example, some catalyst molecules are chemically attached to nonreactive solids to preserve the catalyst from being flushed away when the chemical substrate (the molecule to be converted by the catalyst) is washed by the catalyst immobilized on the structural substrate. Any…

  • Substrate (in chromatography)

    The (usually solid or gel) substance that attracts and noncovalently binds (interacts) with one or more of the molecules in a solution that is passed over that substrate (e.g., in a chromatography column). This preferential binding (interaction with the substrate) enables one or more of the solution’s molecular ingredients to be separated from the other(s).…

  • Substrate (chemical)

    The substance acted upon, for example, by an enzyme. For example, the enzyme amylase breaks starch down into glucose molecules; starch is the substrate (of the enzyme amylase).  

  • Substance P

    A neuropeptide (i.e., peptide produced by cells of the nervous system) which is involved in activation of the immune system, pain sensation, and (when in excess) some psychiatric disorders. In the case of chronic, intractable pain (hypersensitivity), approximately one percent of the nerve cells in the human spine process substance P (thereby “transmitting” its pain…

  • Sulfonylurea (herbicide)-tolerant soybeans

    These are soybeans that have been bred (via insertion of ALS gene) to resist the (weed killing) effects of sulfonylurea-based herbicides. The ALS gene was discovered by Scott Sebastian in 1986.  

  • Structural genomics

    Study of, or discovery of where (gene) sequences are located within the genome, and what (DNA) subunits comprise those sequences.  

  • Structural gene

    A gene that codes for any RNA (ribonucleic acid) or protein product other than a regulator molecule. It determines the primary sequences (i.e., the amino acid sequences) of a polypeptide (protein). A gene in operon directing polypeptide synthesis. A gene that determines the structure of polypeptide chains by controlling the sequence of amino acids.  

  • Stromelysin (MMP-3)

    A collagenase (enzyme) that “clears a path” through living tissue, ahead of tumor cells, thereby enabling a cancer to spread within the body. Member of the matrix metalloproteinase family of enzymes that plays a major role in the degradation of proteoglycans, gelatin, and other constituents of the extracellular matrix. Two forms of stromelysin have been…