Elementary plant Biochemistry and Biotechnology (2+1)

The ß-pleated sheet structure

• Pauling and Corey also proposed a second ordered structure, the ß-pleated sheet for polypeptide.
• This structure is a result of intermolecular hydrogen bonding between the polypeptide chains to form a sheet like arrangement.
• There are two ways in which proteins chains can form the pleated sheet structure. One is with the chains running in the same direction. i.e. the -COOH or NH2 ends of the polypeptide chains lying all at the top or all at the bottom of the sheet. This is called parallel pleated-sheet structure.
• In another type, known as antiparallel ß-pleated sheet structure, the polypeptide chains alternate in such a way that the -COOH end of the one polypeptide is next to the -NH2 end of the other i.e. polypeptide chains run in opposite directions.