Peptides having the following amino acid sequence as well as peptides or proteins which contain this amino acid sequence: R.sup.1-X01-X02-X03-X04-X05-X06-X07-X08-X09-X10-X11-X12-X13-R.sup.2. These peptides have a high affinity for immunoglobulins. Applications of the peptides according to the invention are also described.