Structural Biochemistry/Cell Signaling Pathways/inorganic compounds

Mobile zinc and the gaseous nitric oxide radical are two prominent examples of inorganic compounds that are found in many signaling pathways in living systems. To detect the presence of mobile zinc and nitric oxide, fluorescent probes is used. Fluorescent probes which are dyes that give off light when exposed to light, are excellent tools for detecting zinc and nitric oxide with high spatial and temporal resolution. To monitor biological processes in real time with high spatial resolution, using fluorescent imaging offers an excellent platform. it is known that fluorescent probes maintain good water solubility and membrane permeability.
1- Fluorescent Sensors For Mobile Zinc
The divalent zinc cation, Zn2+, influences a wide metabolic spectrum. Mobile zinc play many physiological roles in zinc-enriched tissues, such as hippocampus, pancreas and prostate. Mobile zinc bioimaging is currently dominated by fluorescent probes. That is due to the technical advances in microscopy instruments and fluorescent sensors have proved to be sensitive and versatile tools for zinc detection in live cells and tissues. In fluorescence microscopy experiments, zinc indicators depend on an increase or rarely a decrease in fluorescence emission intensity.

2- Fluorescent Sensors For Nitric Oxide
Nitric oxide is a free radical gas produced endogenously by a variety of mammalian cells. Nitric oxide play various roles as signal transmitter and it is involved in many physiological and pathological processes. Nitric oxide is synthesized from arginine by a complex reaction and catalyzed by nitric oxide synthase. Nitric oxide synthase is an enzyme that catalyzes the conversion of l-arginine, NADPH, and oxugen to citrulline, nitric oxide and NADP+. There are two strategies in developing the small-moleculed fluorescent probes for nitric oxide. This strtegies are conducted by Pluth M.D et al. in their paper entitled, "Biochemistry of Mobile Zinc and Nitric Oxide Revealed by Fuorescent Sensors". The first is based on organic probes and they often result in bright emission enhancement in the presence of nitric oxide under aerobic conditions. this strategy is widely used. the second strategy is using transition metals to mediate reactivity of an emission dye with nitric oxide. it was found that these probes can be less bright than purely organic probes.