Partial Characterization of Oat and Rye Phytochrome

Molecular Properties of Phytochrome

“…These data are consistent with a nonglobular protein which has a size of about 240,000 daltons leading to the assumption that the native molecule is probably a dimer (Briggs and Rice, 1972). Rice and Briggs, 1973b) and Cundiff (1973) have both reported preliminary equilibrium centrifugation data consistent with this interpretation, a rigorous shape independent determination of the molecular weight of phytochrome remains to be performed. The partial specific volume of undegraded rye phytochrome has been calculated to be 0.728 cm3/g (Rice and Briggs, 1973b).…”

“…This protocol, which is derived from earlier procedures (Siegelman and Firer, 1964;Hopkins and Butler, 1970) with modifications to minimize proteolysis and accommodate differences in properties between the degraded and undegraded forms of phytochrome, utilizes sequential column chromatography with brushite, diethylaminoethyl-cellulose, hydroxylapatite, Bio-Gel Al.5 M and Sephadex G-200. The product has an apparent molecular weight of about 400,000 daltons based upon calibrated gel exclusion chromatography and is homogeneous by gel electrophoresis (Rice and Briggs, 1973b). The purity of such a homogeneous preparation, expressed as the specific absorbance ratio ( & 6 7 / A 2 8 0 after far red irradiation) is about 0.7 (Table 1).…”

“…(1968~) which has unfortunately been acccptcd by standard reference works (Darnall and Klotz, 1972;Sober, 1970). The undegraded molecule elutes from molecular sievc columns with an apparent molecular weight of about 400,000 daltons Rice and Briggs, 1973b) and has a sedimentation value of about 9 S indicative of a much smaller molecule of about 180,000 daltons (Gardner et a/.. 1971;Smith and Correll, 1975). These data are consistent with a nonglobular protein which has a size of about 240,000 daltons leading to the assumption that the native molecule is probably a dimer (Briggs and Rice, 1972).…”

“…Native phytochrome is a multimer of 120,000 dalton subunits as determined by sodium dodecyl sulfate gel electrophoresis (Cundiff, 1973: Rice andBriggs, 1973b;Roux ef al., 1975;Smith and Correll, 1975;cf. Figs.…”

Biliproteins

“…Monomeric phytochrome from oats and rye has a molecu lar weight of about 120000* 200,2011 and it probably has a dumbbell shape* 203,2041 (for reviews see * L ,4 -18 -211 ). The hither to best characterized pigment from oats is readily cleaved by endogenous proteases (at the incision?…”