Further purification of “Triton subchloroplast fraction I” (TSF-I particles). Isolation of a cytochrome-free High-P-700 particle and a complex containing cytochromes f and b6, plastocyanin and iron-sulfur protein(s)

Abstract

The “Triton Subchloroplast Fraction I” or “TSF-I particles” can be further fractionated into a cytochrome fraction and a P-700-containing fraction essentially free of cytochromes. The cytochrome complex contains cytochromes f and b₆ in approx. equimolar amounts, and, in addition, also plastocyanin and one iron-sulfur protein, all in the bound state. Bound plastocyanin was characterized by EPR spectroscopy. The EPR spectrum of the bound iron-sulfur protein resembles that previously detected in Phostosystem I particles under highly reducing conditions at lower than −560 mV.