Letters: August 2024

Flixborough memories

I was interested to read the article on the Flixborough explosion.

At the time, I was a senior lecturer in chemistry at the North Lindsey College of Technology and I had the privilege of teaching staff from the Flixborough site. The following week we were having the GRSC (Part 1) examinations and so several of my students had taken the opportunity to work on the Saturday afternoon to be clear for revision for their paper during the following week.

One of the students was among those who died. His funeral was a very moving experience. Another survived because the explosion caused a sheet of corrugated metal to cover most of his body, even though he was close to the scene of the explosion. I believe he was spotted half an hour later by a foot protruding from that sheet of metal. He had a complete loss of memory for a year and the Royal Society of Chemistry was kind to award him a pass on the basis of his coursework. I believe the shock caused his wife to lose her pregnancy.

The loss of Nypro meant the closure of the GRSC (Part 1) course a year later, when I moved away. The article mentions the blast being felt six miles away. I had the same experience, living in Messingham (around eight miles away). My house shook, and my young children thought it was my wife and I moving furniture around!

I trust that the health and safety rules now make a repetition of such an event unlikely in the future.

J H John Peet
Guildford, UK

How fitting that the 50th anniversary of Flixborough should be marked by the articles in the most recent issue of Chemistry World.

For years, I taught hydrocarbon process safety in the MSc course at the University of Aberdeen, and I recall that one year when I mentioned Flixborough, a member of the class informed me that he had been present there as a plant employee. I cannot remember the student’s name or the year, but it would have been in about 2000. He responded to my invitation to give a short presentation on his recollections of Flixborough and he brought along some very interesting material, including photos and press comments.

On reading the recent Chemistry World article I wondered whether Dave Roberts was that student, but later concluded that he could not have been because he was on annual leave on the Saturday when the accident occurred, whereas my student was at work on that day. It is a very long shot, but if Roberts believes that he might be able to recall my student from among his colleagues at that time he might like to follow up.

Finally, I wish Dave and his wife all good wishes for their golden wedding next year.

Clifford Jones FRSC
University of Chester, UK

Metals in the brain

Not only do sodium, potassium, magnesium and calcium play important roles in brain chemistry, but so too do other metals. Examples include the manganese enzyme glutamine synthetase, which generates the neurotransmitter glutamate; iron in ferroportin, transferrin and ferritin; cobalt as vitamin B12; copper in dopamine β-hydroxylase and metallothionein-3 (MT3) and zinc in MT3, transcription factors, transporters and matrix metalloproteinases. Indeed, the brain is rich in iron (about 720µM) and zinc (around 150μM, reaching 1mM in some synaptic neurons).

Intriguing is the discovery of metallic Fe(0) and Cu(0) as nano-deposits in amyloid plaques from the brain tissue of people with Alzheimer’s disease. The function of these deposits and whether they can also occur in neurotypical brains has yet to be investigated. Further exploration of the roles of both natural ‘essential’ and non-essential metals (including inhaled pollutants) in the brain may lead to breakthroughs in understanding normal brain functions as well as neurodegeneration.

We can confidently say that neurochemists should do more than ‘analyze the biochemistry and molecular biology of organic compounds in the nervous system’, as Wikipedia’s neurochemistry entry states at time of writing. Inorganic neurochemistry is important too.

Peter Sadler FRSC
University of Warwick, UK

A structured argument

The recent article on Z-DNA clearly summarised past and current opinions and activities on this unusual form of the double helix, in a way that was very accessible to non-experts. Today, the left-handed topology of Z-DNA is widely accepted by the scientific community, and with good reason.

Clive Delmonte’s letter challenged the view that Z-DNA is left-handed. The letter also incorrectly described the initial determination of the Z-DNA structure by Alex Rich and colleagues. Contrary to Delmonte’s assertion, the high-resolution crystal structure of Z-DNA was not determined by fitting a model to the diffraction data (the Rich group did initially try to fit right-handed DNA models to the diffraction data, but without success). Instead, the structure was determined ab initio by the long-established method of multiple isomorphous replacement (MIR), in which heavy metal ions are introduced into the crystal lattice and bind to DNA. MIR has been the standard method of determining crystal structures for many hundreds of proteins and nucleic acids since the 1950s. It makes no assumptions about the underlying structure and produces electron density distributions that show individual atomic positions in a crystal structure. We submitted our own letters pointing this out.

We were surprised to see another letter from Delmonte, which ignores our letters, and raises more highly selective points questioning the structure of Z-DNA. We are not going to prolong this correspondence. However, while it is Delmonte’s right to hold these views and we defend that right, readers of Chemistry World should know this viewpoint does not reflect the broad consensus of the scientific community and that no experimental data nor any peer-reviewed publications have been provided to disprove the many structural studies showing Z-DNA adopts a left-handed helix.

We are concerned that making such assertions without evidence debases the reputation of the chemical sciences and does a real disservice to crystallography and crystallographers.

Stephen Neidle FRSC
Harry Powell MRSC
Via email

Chemistry World welcomes letters, which should be concise (normally fewer than 300 words) and timely. Those selected for publication are subject to editing for clarity and length. Letters should be marked ‘for publication’ and sent to chemistryworld@rsc.org

We do not routinely acknowledge letters.