Phytochromes in photosynthetically competent plants. Final report.

摘要

Major improvements have been made in the purification of green-oat phytochrome. An effective protease inhibitor has been incorporated, the scale of preparations has been increased greatly, an immunodominant contaminant has been eliminated, and the extent of purification has been increased by at least a factor of ten. Five new MAbs and rabbit PAbs to green-oat phytochrome, as well as rabbit PAbs to a synthetic, putative green-oat phytochrome peptide, have been produced and characterized, together with two MAbs to green-oat phytochrome that had been identified previously. Our earlier hypothesis that green-oat phytochrome itself consists of two types was found to be true. One type of green-oat phytochrome has an apparent monomer size of 125 kDa while the other is 123 kDa. The latter undergoes a Zn(sup 2+)-induced mobility shift during SDS PAGE and the two phytochromes are immunochemically distinct from one another. Affinity columns prepared with MAbs to green-oat phytochrome have been used to purify 125-kDa green-oat phytochrome to near homogeneity. A proteolytically derived peptide has been isolated from immunopurified green-oat phytochrome and 19 residues have been determined by microsequencing. The results verify that in monocotyledons as well as dicotyledons green- and etiolated-oat phytochromes derive from different genes.