Carbenes undergo both intermolecular and intramolecular insertion reactions. There are two classes of triplex DNA&colon; intermolecular and intramolecular formations. When an intramolecular insertion is possible, no intermolecular insertions are seen. This sequence contains six cysteine residues that form three intramolecular disulfide bonds. Subsequent transport is promoted through the reduction of intramolecular disulfide bonds by GLRX catalysis. Human EGF is 6-kDa and has 53 amino acid residues and three intramolecular disulfide bonds. Then, followed by intramolecular nucleophilic substitution, the second hydroxyl group attacks the electron deficient carbon. IGF-1 consists of 70 amino acids in a single chain with three intramolecular disulfide bridges. On the right-hand side we separated "intramolecular" (formula 259) and "intermolecular" (formula 260) terms. The polarizability of the nucleophile or involvement of intramolecular catalysis also plays a role. They are slightly soluble in ethanol and contain only intramolecular disulfide links. Last is the intramolecular azomethine ylide reaction with alkene. Formation of intramolecular hydrogen bonds provides another important contribution to protein stability. SU-8 is an example of an intramolecular photopolymerization forming a matrix of cross-linked material. In electroporation, excessive leakage of ions and intramolecular components results in cell death.