The BR xmas lecture: 37 degrees

pinno

During a study of photosynthesis in Elodea Canedensis (Canadian Pondweed), the rate of photosynthesis was optimum around the mid thirties. The graph was disproportionate though. A steady rise from 15 degrees (roughly) in a straight line but a steep decline soon after the temperature of 37 degrees centigrade was reached.
This threw up a few questions. Many living organisms thrive in the mid 30 degree range. Bacteria, plants ameoba and mammals for example.
What are the implications of 37 degrees ? What is happening chemically/biologically ? Was the primordial soup this temperature ? Why is this temperature so conducive to life ? Is it a matter of physics, rather than chemistry ?

Gizmodo

So what you're saying is that it's amazing anything is alive in Scotland?

tim_wand

Same thing happened with my VO2 and Max Wattage post 37. Should have known it was something to do with my close relationship to pondlife.

team47b

Just made today's bread, best temperature for bread to proof is 37 degrees.

Just made tomorrow's yoghurt, best temperature to start the bacterial reaction is 37 degrees.

team47b

...paused to put bread in oven...

this is the ideal temperature for the body's enzymes and proteins to work, so it's biochemical.

Therefore I conclude we are yeast and bacteria wrapped up in a 'human' bag, a yoghurt sandwich if you like

buckmulligan

This is a very good question, I'm a research scientist studying biochemistry for a living and I don't even really know the answer!

The steady rise you mention from 15-37 degrees C is basic thermodynamics, chemical reactions happen faster at higher temperatures; the rapid drop off you see above 37 is because certain critical proteins involved in these processes become unstable and can no longer perform their function. Different proteins can have a wide range of temperature stability, almost all are fine up to the mid-thirties as you say, but a fair few are stable up to 70-80 degrees C and beyond.

As for the question 'why 37?' I'm really not sure. The primordial soup was almost certainly significantly hotter than this as evidenced by a whole raft of geological and biological evidence. I can only assume that it's to do with the stability of the fundamental components of a living cell. It's cool enough so that things like DNA and cell membranes are nice and stable, yet a warm enough temperature to promote a high turnover rate of chemical reactions (as mentioned above).

As an interesting demonstration of how well-adapted (or badly as it proves to be!) most organisms are to temperature, in university we learnt about some old French king (maybe one of the Louis') who was suffering from syphillis as was fairly common back in the day. He also contracted malaria, and the ensuing fever caused his bodily temperature to rise up to a recorded 39 and a half degrees. Although he was extremely ill during this fever, it was a high enough temperature to kill off the syphillis bacteria in his body!

That doesn't really answer your question at all, but I'll Google it!