A good critical mass in photosynthesis research

Interviewer: What led you to return to Australia, to CSIRO Plant Industry?

I had resigned from CSIRO Wool Research after I was awarded the ICI fellowship; I didn’t want to come back at that stage. But during my post-doc the lab had played some cricket matches with University College, London. One member of their team being John Falk, who had worked there for several years on porphyrins. He had been appointed to head the biochemistry section of the Division of Plant Industry. Subsequently he came to Cambridge and said he would like to offer me a job in Canberra to set up their chromatography facilities but he had to consult the Chief, Otto Frankel, to see if a position was available. (The Executive of the day still had a pool of positions which they handed out at their discretion.) Knowing the persuasive power of Otto, I believe he didn’t have a great deal of trouble in getting the position.

So this was an opportunity to get you into chlorophyll protein complexes?

Yes, that’s right. I came back and set up chromatography facilities fairly quickly, and then, with the experience in the haemoglobins – and with John Falk's interest in porphyrins, and also with Rudi Lemberg, in Sydney, having developed quite a school in haem pigments – I decided to investigate chlorophyll complexes.

Soon after I arrived, a paper from the Carnegie Institute in Stanford, California, reported the isolation of a soluble protochlorophyll complex from dark-grown bean leaves. I thought, ‘If that’s soluble, I’ll see whether I can purify it.’ So I developed the purification procedure, including density electrophoresis – but in order to be able to assay this protein you had to prepare it in weak green light. Protochlorophyll is converted to chlorophyll in red light; it is a porphyrin going to a chlorin. So I had to set up a whole lab, black it out, put in weak green lights, do the whole purification, and then illuminate the protochlorophyll protein complex in a spectrophotometer and follow the kinetics of the conversion. The kinetics were a little complicated too. They were interpreted in terms of the structure of the hydrogen donor in relation to the protochlorophyll, which needs two hydrogens to go to chlorophyll. I was not able at that time to identify the donor.

That work extended over quite a few years, Keith. Who were your colleagues?

The colleague for the work on the protochlorophyll was myself. But after that I went back to the chlorophyll-protein complexes, where the real rewards were. I was then treasurer of the newly formed Australian Biochemical Society and the secretary was Fred Collins, a lipid biochemist at the John Curtin School. I told him, ‘I’m trying to separate these chlorophyll complexes but you’ve got to use detergents. When I use the normal anionic or cationic detergents I don’t get the properties of the chlorophyll as it is in the leaf.’ He suggested that I try a natural detergent called digitonin, which had been used very successfully to separate the rods containing the retinin from the eye, with the pigment in a natural state. Sure enough, digitonin didn’t wreck the chlorophyll system, and on doing a differential centrifugation I found fractions with different chlorophyll a:b ratios.

An enormous contribution to that advance and to working out what was happening came from the fact that I was working in a biochemistry department with a good critical mass, with colleagues working on projects which were different but had related techniques. For instance, Don Spencer and John Possingham were working on nutrition of plants – they wanted to work out the role of manganese and how it was related to photosynthesis. So they had set up the methods for looking at the electron transport in different parts of the photosynthetic chain. Cyril Appleby had worked on his PhD in Melbourne with Bob Morton, who worked on cytochromes. He persuaded the Division to buy a Cary spectrophotometer to look at cytochromes, so it was ready to go when I had the fractions with different chlorophyll a:b ratios, first of all to look at the photochemical reactions but then to look at their composition. And John David had the analytical methods set up for all the trace elements, so he was able to analyse the fractions for relevant trace elements.

The Cary spectrophotometer had to be adapted. We had highly scattering samples. No-one else could determine the cytochromes in green material: the scattering was too great, the chlorophyll absorbed much of the light. But with the help of our good workshop and Cyril Appleby’s contribution, we made an attachment for the Cary which let us do the spectra of scattering materials. Also, we developed a liquid nitrogen attachment for determining spectra at liquid nitrogen temperature. This led to discoveries about the cytochromes which people said we couldn’t do with all that chlorophyll there. (Others were extracting the chlorophyll with acetone and other solvents and destroying the native chlorophyll-protein complexes.)

Then Jan Anderson came on board, soon after I had done the first experiments. She was a tremendous colleague. We characterised the chlorophyll-containing fractions to convince the world that there was a separation of the photosystems.

Focus questions

• Boardman mentions that when he returned to Australia in the mid-1950s, the Executive of CSIRO had a pool of positions, which they handed out at their discretion. Do you think that job appointments at CSIRO are made like that today? What are the advantages and disadvantages of appointing scientists as CSIRO did in the 1950s?

• The success of a research project is often dependent on the cooperation of researchers who have different areas of expertise. Does this statement apply to Boardman's research? Point out some examples in this extract.