John P. Toscano
Johns Hopkins University
New Chemistry Building
3400 North Charles St.
Baltimore, MD 21218
Ph.D. - Yale University
NIH Postdoctoral Fellow - Ohio State University
The Toscano group’s main interests have focused on the application of nanosecond time-resolved infrared (TRIR) spectroscopy to the study of organic reactive intermediates and the development of novel photochemical precursors to nitric oxide (NO). More recently, our research activities have turned to study of the fundamental chemistry and biochemistry of nitroxyl (HNO). This one-electron reduced and protonated congener of NO has recently received significant attention, especially as a potential alternative to current treatments of cardiac failure.
Although unique biological responses have been attributed to HNO, compared with its redox sibling NO, much less is known about the fundamental solution chemistry of this deceptively complicated system. The deprotonated form (NO anion) is isoelectronic with oxygen and, like oxygen, has a triplet ground state. Thus, simple protonation of NO anion is formally spin forbidden and uncertainties regarding the pKa of HNO have only recently been clarified; a value of approximately 11.4 has been obtained by several methods, confirming that HNO is the physiologically relevant protonation state. A major reaction pathway for HNO is dimerization (through hyponitrous acid HON=NOH) to provide ultimately nitrous oxide (N2O) and water. Thus, HNO cannot be stored and must be produced from an appropriate precursor. Unfortunately, only a very limited number of precursors suitable for biological studies currently exist.
In order to advance our understanding of HNO chemistry and biochemistry we are actively pursuing research in the following areas:
(1) Development of new thermal and photochemical precursors to HNO
(2) Development of new analytical tools for the detection and study of HNO
(3) Elucidation of fundamental HNO solution-phase chemistry
(4) Characterization of HNO-induced modifications of phospholamban, an important regulatory protein involved in the control of cardiac function