Abstract
Conjugates of αs1, κ-caseins and αs1-κ-casein complex were prepared with dimethyl-aminonaphthalenesulfonate and pyrenebutyrate. Their fluorescence lifetimes and the rotational relaxation times were measured by single photon counting technique and
fluorescence depolarization technique, respectively. Both dimethylaminonaphthalenesul-fonate and pyrenebutyrate conjugates had more than two lifetimes and the longer lifetime of pyrenebutyrate conjugates was near 140 nsec.
The rotational relaxation time of pyrenebutyrate αs1-κ-casein complex was smaller than that of pyrenebutyrate κ-casein polymer, which suggested that the complex formation of
αs1- and κ-casein polymers led to dissociation of the κ-casein polymer.
Changes of the rotational relaxation time as a function of weight ratio of αs1- and κ-casein polymers (αs1/κ) showed the specific variation and it was suggested that 4 moles of αs1-κ-casein complex were formed from one mole of κ-casein polymer.
