CHNH2 CHNH2 @ @ @ COOH COOH COOH The transformation of cystein to cystin occurs in the air through oxygen, naturally with cooperation of constantly present traces of iron. This simplest form of sulphur-containing building stone is determining for the function of sulphur in the protein molecule, but, through further compounds, the complex gains some new properties. So cystin or cystein forms a dipeptid with glutaminic acid- CH (NH2) COOH = CH2 CH2 COOH namely the glutathion discovered by Hopkins in 1920. Probably this compound is present in most cells. The easy oxidation to cystin form and likewise the easy reduction to the cystein form also remains in this compound. In contrast to cystin, the cystein form of glutathion is soluble in the fluids of the body. This is a sign that the complex form is better adapted to the functional DOSE : Usually D 6 (trituration).
In group VI of the periodic system sulphur has such central position that we can designate the group according to it, particularly since the first element of the group, oxygen, provides no medicinal substance. The transition from the non- metallic sulphur to the metallic tellurium will come into evidence in the effect picture of this substance. Selenium and tellurium appear considerably less significant than sulphur and its compounds.
In the earth, sulphur, S, is the prevailing element of the chalkosphere. In this layer of the earth, which perhaps extends about 1200-2900 km: in depth, those metals are abundant which have a special affinity for sulphur. Here sulphur plays a role for the so-called metallogenous elements (earth builders) which has its group neighbor, oxygen, in the lithosphere for the petrogenous elements (stone builders). With the exception of the noble metals, all heavy metals occur in nature as sulphur compounds. In the earth crust the sulphur compounds of heavy metals are fairly strangers. However, we shall find the relation of sulphur to metallic foreign substance to be of some significance. Through volcanic eruptions sulphur comes from the great depths to the surface of the earth. The life- endangering forms of this volcanic source, hydrogen sulphide, H2S, and sulphur dioxide, SO2, reciprocal actions of which also lead to the deposition of free sulphur, are bound on the earth surface mostly as completely oxidized compounds, sulphates of alkalies, and particularly as earthy alkalies. In this form they are utilizable for the assimilative activity of of plants. The plants reduce sulphate and build organic sulphur compounds. In the reduction from sulphates, bacteria of the soil also participate. Other bacteria and certain algae (for example Beggiatoa) further oxidize H2S and deposit sulphur in their cells; they gain energy from this oxidation as other forms of the life from the oxidation of carbohydrates.
For the animal organism the building activity of plants is a necessary preliminary step for their sulphur metabolism; they convert plant protein compounds for their own function. More or less completely oxidized sulphur is excreted, or after death the animal organism undergoes decomposition into H2S. Then the circulation of sulphur can begin anew.
The chemical property of sulphur which occurs as an atom as the negative divalent (H2S) as well as the positive six valent (SO3=H2SO4 – H2O), remains decisive in the living organism. To lead the change between oxidation and reduction is the chief task of organically bound sulphur. So far the sulphur serves merely as an intermediator and its organic compound is not destroyed, so this function is a reversible catalysis. But the sulphur – containing building stone destroys itself in oxidative decomposition and indeed it seems to offer an especially good point of attack in the protein complex.
The diverse forms in which sulphur is able to appear according to its molecular structure, its modifications, gain considerable significance for the medicinal use of the pure substance. In homoeopathic uses these differences of modifications in general are exceeded through the extensive subdivision.
All proteins of cells and their higher split products (with the exception of peptones and protamines) contain sulphur. Even from this the great significance of sulphur for the organism can be measured. An important, perhaps the single, sulphur containing building stone is cystin. Cystin is dicystein, a product of the union of two cystein molecules with the liberation of H2. (Cystein is thio-amino-propionic acid). Between cystin and cystein we have a transformation relationship of the type: