Types of Compounds. Ionic compounds are compounds composed of ions, charged particles that form when an atom (or group of atoms, in the case of polyatomic ions) gains or loses electrons. 1  A cation is a positively charged ion. 2  An anion is a negatively charged ion.
Porins are members of an extended family of transmembrane proteins found in the outer membrane of gram negative bacteria such as E. coli, or in the outer membranes of mitochondria in eukaryotes. The general porins provide a simple diffusion pathway across the membrane for molecules less than 1 kDa with little substrate selectivity.
1 Folding can also result in covalent bonding between the R groups of cysteine amino acids. 2  This type of bonding forms what is called a disulfide bridge. 3  Interactions called van der Waals forces also assist in the stabilization of protein structure.roteins are biological polymers composed of amino acids. Amino acids, linked together by peptide bonds, form a polypeptide chain. One or more polypeptide chains twisted into a 3-D shape form a protein. Proteins have complex shapes that include various folds, loops, and curves.