 Alpha sheet

Alpha sheet (also known as alpha pleated sheet or polar pleated sheet) is an atypical secondary structure in proteins, first proposed by Linus Pauling and Robert Corey in 1951.The hydrogen bonding pattern in an alpha sheet is similar to that of a beta sheet, but the orientation of the carbonyl and amino groups in the peptide bond units is distinctive; in a single strand, all the carbonyl groups are oriented in the same direction on one side of the pleat, and all the amino groups are oriented in the same direction on the opposite side of the sheet.