In biochemistry, most work is done at room temperature. Yet, basic thermodynamics tells us that affinities often change with temperature, in positive or negative directions depending on the entropy/enthalpy contributions. Thermal transitions can occur which both quantitatively and qualitatively change the behavior of the molecules of study. In enzymatic reactions rate-limited by diffusion-mediated product release, the increased rate of diffusion could increase the rate of product release above the rate of the chemical step, such that the chemical step becomes rate-limiting. If one discovers a compound that potently inhibits this enzyme at 25C, it may have reduced effect at 37C, or none at all. Likewise, if an enzyme is predominantly dimerized at 25C based mostly on enthalpic contributions, this dimer may not even exist at 37C. Screening compounds against the dimer may be of little relevance to the situation in vivo. The converse could happen if dimerization is entropically driven. Temperature-dependent changes in solution properties can also obscure the relevance of 25C results to 37C, such as viscosity.
I welcome everyone's two cents.
I don't think it's true that "Biochemistry experiments are done at room temperature, not 37C." They are often done at 37C. However, I do most of my enzyme assays at room temperature because I usually work with 384-well microtiter plates, and it is difficult to establish a consistent elevated temperature across the whole plate on a short time scale. It is important to report the temperature in any publications. Surprisingly, this detail is often forgotten in Methods sections. Also, "room temperature" should be defined as a specific temperature or range of temperatures.
If a detailed mechanistic understanding of the biochemical mechanism is being investigated, it is very important to be clear about the temperature. Moreover, varying the temperature can provide useful information about the chemical mechanism, such as the activation energy of the reaction.
Maybe not applicable to all enzymes, but I think it is. DNA binding of E.coli's Klenow fragment DNA polymerase to double stranded DNA is entropically driven at low temperatures (~ 4 Celsius), but enthalpically driven at physiological temperatures (~ 37 Celsius) [1]. However, although the thermodynamic mechanism of binding changes, the DNA binding affinity (KD) hardly changes less than a factor of 2 difference. Therefore any difference in binding affinity over the temperature range could be attributed to experimental error.
I believe the enzymatic activity KM and kcat might have more meaningful parameter changes over temperatures, but based on this table of binding affinity measurements if there is an impact on activity it would nothing to do with temperature vs DNA binding affinities [1].
However, I do think for enzymes which form oligomers, temperature could have an impact on oligomerization due to thermodynamic penalties of solvation.
Reference
1. Datta, K., Wowor, A. J., Richard, A. J., & LiCata, V. J. (2006). Temperature dependence and thermodynamics of Klenow polymerase binding to primed-template DNA. Biophysical journal, 90(5), 1739-1751.
I love the answers provided by Adam B Shapiro and Adron Ung. I'm thinking of something different. If we really want to approximate biological functional interactions, then we need to try to reproduce the biological milieu, instead of running our reactions in simplified buffers. Sometimes we can only guess about the pH, ionic strength, and the small and large molecules that are evolved to interact competitively and otherwise. For example think of measuring biding of pure oxygen to pure hemoglobin in PBST. Using pure reagents you'll obtain a clean answer. But you won't really learn very much about what happens in vivo.
One solution is replicate the relevant experiment both at 25 degrees as well as at 37 degrees. However, it should be remembered that 'in vitro system' and 'in vivo system' may work differently and hence results can vary. In the 'in vitro system', contributing factors like pH, temperature, concentrations of compounds are limited and known, and hence are tightly controlled, while in the 'in vivo system', there may be thousands of unknown contributing factors affecting the results.
Most of Body Fluid Enzymes get activated at 37 degree C. This Reactions are Time regulated . All this process Occurs in Close Compartment of Human Body. Results May Vary. But For Comparison Purpose Results are acceptable..
- the thermophysical properties and chemical kinetics in biomaterials vary nonlinearly from temperature, therefore, in systems with highly variable properties, approximations of room temperatures can give an incorrect result (This is partially described in the works on soft matter physics by M. Kleman and O. D. Lavrentovich)
create conditions for uniform heating of the tissue (if it is a biopsy, for example) in saline or a gremetic bag (but in this case the question is how you will effectively probe it or investigate it in some other way). it is unclear what exactly you are examining - individual cells, microfragments, areas (biopsy) or whole organs? In the latter case, it is possible to organize artificial blood flow with the selection of initial conditions according to blood temperature
Your initial statement is questionable, as Adam B Shapiro stated, most biochemical assays are performed in physiological temperatures, if possible. It is however almost impossible to mimic the in vivo situation (temperature being actually the easiest parameter to mimic), if you consider the molecular crowding and the presence of so many potential binding/inhibiting/activating/modifying molecules that you find in the biological system. Therefore, any in vitro finding needs verification by an in vivo assay if possible, unless you "just" want to look at the kinetic and thermodynamic details of a reaction.