Table 2

Binding of BV, PCB, and PEB to Agp1 in the native state (“without SDS”) and after SDS-denaturation

ChromophoreWithout SDSWith SDSAfter DTNB with SDSMutant C20A with SDS
BV99  ± 1%98  ± 1%0  ± 2%*1  ± 3%*
PCB95  ± 3%5  ± 2%*n.d.n.d.
PEB36  ± 2%8  ± 2%*n.d.n.d.
  • After mixing bilin and apo-Agp1, free bilins were separated from the protein using pre-packed desalting columns, and the fraction that remained attached to the protein was determined by UV-VIS spectroscopy. Mean values of three separate chromophore/protein mixes from one apoprotein sample ± S.E.; n.d., not determined. When the value of an SDS-treated sample was low (*), the background value of the free chromophore without protein was subtracted (see Materials and Methods).