The key role of nitric oxide (NO) in numerous vital biological processes, including the human body in normal and pathological conditions, poses an urgent problem of dosed and regulated flow of objects of interest. S-Nitrosothiols have received much attention in the chemistry of NO-based signaling in living systems, because they serve as donors of both the nitrosonium ion NO+ and of NO. S-Nitrosoglutathione (GSNO) mimics the beneficial activity of endothelial Nitric Oxide Synthase-derived nitric oxide in organisms. For example, administration of exogenous of GSNO or enhancing the level of endogenous GSNO protects against neurovascular injury (endothelial dysfunction) of mouse models, reduces brain infarctions and edema, improves neurobehavioral functions, attenuates cerebral ischemia-reperfusion (IR) injury in a mice, exhibits anti-ischemic and anti-inflammatory functions, and stimulates neurorepair and functional recovery following experimental stroke in rats. Due to the possibility of synthesizing almost unlimited number of the iron–sulfur–nitrosyl complexes (ISNC) of various structures, stability, and bioavailability, they can be used for predictable regulation of synthesis of nitric oxide in biological systems. The complexes showed encouraging results and their therapeutic potential are subject of discussion. Principles and recent developments of catalysis by abzyme, a monoclonal antibody with catalytic activity of a corresponding enzyme and their potential applications of catalytic antibodies in reactive immunization, therapy, biochemical analysis, and biotechnology were described. Data on artificial enzymes of common interest not included in previous chapter are discussed in a separate section.