. . . . . "CSP: strong covalent bond between two sulfur atoms; this bond is very important to the folding, structure, and function of proteins; also called a disulfide bridge.,NCI: A disulfide linkage is a covalent bond between 2 sulfide atoms from the thiol group of 2 cysteine residues (S-S). They occur both interstrand and intrastrand." . . . . . .