Abstract
Sulfur is present in human and animal tissues, in organic compounds (such as sulfur amino acids), and inorganic compounds (such as hydrogen sulfide). Hydrogen sulfide can be sourced from a pool of compounds containing sulfane sulfur. The presence of sulfane sulfur has been observed, over the years in human and animal tissues, as well as cell cultures. The cold cyanolysis method (Wood's method), determined sulfane sulfur contents ranged from 60 to 400 nmol per mg of protein. In amphibians, the level of sulfane sulfur changes seasonally. No gender differences relating to sulfane sulfur levels were found in mice. External factors such as cyanide, menadione (induces oxidative stress), heavy metal ions, or changes in the level of L-cysteine and other sulfur compounds which result from mutations of genes for enzymes involved in the transformation of these compounds, temporarily affect the level of sulfane sulfur, which, however, returns to the control level, which illustrates the adaptation to changed conditions and the tendency to maintain the level of sulfane sulfur. This points to the essential importance of sulfane sulfur for living organisms.