In vitro activity: Novobiocin also interacts with Hsp90, altering the affinity of the chaperone for geldanamycin and radicicol and causing in vitro and in vivo depletion of key regulatory Hsp90-dependent kinases including v-Src, Raf-1, and p185(ErbB2). Novobiocin interferes with association of the co-chaperones Hsc70 and p23 with Hsp90. Novobiocin specifically inhibits the maturation of the heme-regulated eIF2alpha kinase (HRI) in a concentration-dependent manner. Novobiocin induces the dissociation of Hsp90 and Cdc37 from immature HRI, while the Hsp90 cochaperones p23, FKBP52, and protein phosphatase 5 remained associated with immature HRI. Novobiocin causes morphological and biochemical changes which lead to induction of cell death exhibiting characteristic features of metazoan apoptosis. Novobiocin, a HSP90 inhibitor, could decrease the expression of SMYD3 and dose dependently inhibit the proliferation and migration of MDA-MB-231 human breast cancer cells. Novobiocin can inhibit the migration of breast cancer cells and such event may involve the downregulation of SMYD3. Novobiocin, an aminocoumarin antibiotic, interferes with heat shock protein 90 and hypoxia inducible factor dependent gene expression and thus compromises cell survival. Novobiocin results in a significant increase of [Ca(2+)]i, decrease of forward scatter, increase of annexin-V-binding and enhances ceramide formation. Novobiocin stimulates eryptosis, an effect at least in part due to entry of extracellular Ca(2+) and formation of ceramide.

Cell Assay: Antibacterial Novobiocin, also known as albamycin or cathomycin, is an aminocoumarin antibiotic that is produced by the actinomycete Streptomyces niveus, which has recently been identified as a subjective synonym for S. spheroides a member of the order Actinobacteria . Other aminocoumarin antibiotics include clorobiocin and coumermycin A1. The molecular basis of action of novobiocin, and other related drugs clorobiocin and coumermycin A1 has been examined. Aminocoumarins are very potent inhibitors of bacterial DNA gyrase and work by targeting the GyrB subunit of the enzyme involved in energy transduction. Novobiocin as well as the other aminocoumarin antibiotics act as competitive inhibitors of the ATPase reaction catalysed by GyrB. The potency of novobiocin is considerably higher than that of the fluoroquinolones that also target DNA gyrase, but at a different site on the enzyme. The GyrA subunit is involved in the DNA nicking and ligation activity