Abstract
Cytochrome f has been purified from spinach chloroplasts and from the photosynthetic membranes of the cyanobacterium Spirulina maxima. The spinach protein has an isoelectric point of 5.2 and gives a single band on isoelectric focusing gels. The S. maxima cytochrome shows a major band with a pI of 4.01 and a minor band with a pI of 3.97. S. maxima cytochrome f has a molecular weight approximately 38,000 and is monomeric, while the spinach protein is slightly smaller, approximately 36,000 daltons, and aggregates to form an octamer. S. maxima cytochrome f has an E'0 of +339 mV which is close to that of cytochromes f from higher plants. The NH2-terminal amino acid sequences of the cytochromes show striking similarities. Spinach cytochrome f shows a clear preference for oxidation by spinach plastocyanin and S. maxima cytochrome f is more readily oxidized by its in vivo reaction partner, cytochrome c553.
Highlights
Cytochrome f has been puriqed from spinach chlo- Aphanizomenon flos-aquae was collected from Lake Okoboji, Iowa
There are several problems that make the preparation of homogeneous cytochrome f from S. maxima extremely difficult
With a higher plant such as spinach, one could start with several kilograms of leaves and isolate from them concentrated photosynthetic membranes in a small volume
Summary
S. maxima cytochromef has a molecular weight approximately 38,000 and is Spinach plastocyanin was prepared by the procedure of Anderson and McCarty [2]. All spectra were measured at room temperature in a 50 mM sodium phosphate buffer (pH 7.5). Sodium ascorbate and potassium ferricyanide were used to prepare the oxidized and the monomericw, hilethespinachprotein is slightly reduced cytochromes. To form an octamer.S. maxima cytochromefhas an E’, Molecular weight determinations were carried out on a column (1.5 of +339 mV which is close to that of cytochromesf from X 90cm) packed either with Sephadex G-75 or G-200and equilibrated higher plants.The NH2-terminalamino acid sequences of the cytochromes show striking similarities. Spinach cytochromef shows a clear preference for oxidatbioyn spinach plastocyanin and S. maxima cytochrome f is with 50 mM ammonium bicarbonate solution (pH 8.0).
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
