Preparation and Properties of Trifluoroacetylated κ-Casein

Abstract

Blocking the free amino groups of κ-casein with trifluoroacetyl-groups resulted in markedly altered properties of the protein. Trifluoroacetylated κ-casein was not able to stabilize αs1-casein in the presence of calcium ions, but this ability was fully restored after removal of the blocking groups. Trifluoroacetylated-κ-casein was susceptible to rennin action, but the liberated para-κ-casein was completely soluble and did not yield the typical para-κ-casein clot. This loss of characteristic properties is attributed to structural alterations produced by the change in ionic character or by steric effects of the blocking trifluoroacetyl-groups.