The process has evolved to applying solid lubricants such as molybdenum disulphide to surfaces. However, MPO is unique in existing as a catalytic dimer bridged by a disulphide bond. He formed a cartel to control global business with carbon disulphide. Invertebrate connective tissue proteins based on disulphide links appear to be radically different. All have four conserved cysteines that probably form two disulphide bonds. The toxin with four disulphide bonds is from TsTX-IV. Proteins with disulphide bonds and glycosylation can be efficiently produced in yeast. This domain contains ten conserved cysteines that form five disulphide bridges. The monomers are held together by 2 interchain disulphide bonds. IL-4 has a compact, globular fold (similar to other cytokines), stabilised by 3 disulphide bonds. The monomers are held with disulphide bridges and 3 pairs of cysteine amino acids. Colipase is a small protein (12K) with five conserved disulphide bonds. Disulphide bonds exist between Cys and Cys, as well as Cys and Cys.