This is a paper on flavoproteins (proteins that bind and use FAD), reviewing and presenting a glimpse of ongoing work of the Perham lab on flavoproteins being carried out in the nineteen nineties, at Cambridge, while I was briefly in the lab (for about two years), before returning to an independent position in India. I worked with glutathione reductase, showing that in the context of the whole four-domain protein, i.e.., without excising the individual domains from the polypeptide, the first domain with the FAD-binding property is the most structurally-stable (monitored by changes in FAD quantum yield upon release during unfolding), the second domain with the NADP-binding property is the second-most stable (monitored by its residual 2’5’-ADP agarose binding property during unfolding, this being an analog of NADP), and the fourth domain, also known as the interface domain being the least stable of the protein’s domains (monitored through release of a non 6X-His tagged subunit by its partner, 6X-His tagged subunit in a population of heterodimeric glutathione reductase). Unfortunately, I came back to a job as an independent PI and the full paper did not get submitted. I also worked to replace the interface domain of glutathione reductase by the interface domain of the homologous dihydrolipoamide dehydrogenase (E3 component of pyruvate dehydrogenase), but this work remained incomplete by the time I returned to a job in India. With many new responsibilities here, no internet (this was 1996, in India) and scant access to telephone or facsimile, and with Richard’s responsibilities at work and home gradually also going through the roof, we just kept discussing our return to this work to bring it to completion by email but never eventually got around to doing so. Some glimpses of these and other works are presented in this paper.

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