Chemistry:Dunathan stereoelectronic hypothesis
Dunathan stereoelectronic hypothesis is a concept in chemistry to explain the stereospecefic cleavage of bonds using pyridoxal phosphate. This occurs because stereoelectronic effects controls the actions of the enzyme.[1]
History
Before the correlation between fold type and reaction correlation of proteins were understood, Harmon C. Dunathan, a chemist at Haverford College[2] proposed that the bond that is cleaved using pyridoxal is perpendicular to the system.[3] Though an important concept in bioorganic chemistry, it is now known that enzyme conformations play a critical role in the final chemical reaction.
Mode of action
The transition state is stabilized by the extended pi bond network (formation of anion).[4] Furthermore hyperconjugation caused by the extended network draws electrons from the bond to be cleaved, thus weakening the chemical bond and making it labile[5] The sigma bond that is parallel to the pi bond network will break.[6] The bond that has the highest chance of being cleaved is one with the largest HOMO-LUMO overlap.[7] This effect might be effected by electrostatic effects within the enzyme.[8]
Applications
This was seen in transferase and future interests lie in decarboxylation in various catalytic cycles.[9]
References
- ↑ Silverman, Richard B. (2002). The organic chemistry of enzyme-catalyzed reactions (Rev. ed.). San Diego, Calif. [u.a.]: Acad. Press. ISBN 9780126437317.
- ↑ "MacKay Web". http://www.haverford.edu/chem/mackay/ColinWeb/MacKay_Web.html.
- ↑ "Stereoelectronic". http://chemgroups.ucdavis.edu/~toney/Stereoelectronic.html.
- ↑ "Chem 654: Four Specialized Adaptations In Catalytic Proteins" (in en-US). 6 October 2011. http://chem.uaf.edu/keller/Courses/654Fa11/PDF/654-10-6-11.pdf.
- ↑ Toney, Michael D. (November 2011). "Controlling reaction specificity in pyridoxal phosphate enzymes" (in en). Biochimica et Biophysica Acta (BBA) - Proteins and Proteomics 1814 (11): 1407–1418. doi:10.1016/j.bbapap.2011.05.019. PMID 21664990. PMC 3359020. http://chemgroups.ucdavis.edu/~toney/Publications/BBA%20-%20Proteins%20and%20Proteomics%202011%20Toney.pdf. Retrieved 9 November 2022.
- ↑ http://faculty.washington.edu/gelb/Chp9.ppt
- ↑ Mohammed Shahid, ed (2011). Biomedical aspects of histamine current perspectives. Dordrecht: Springer. ISBN 9789048193493.
- ↑ "Archived copy". http://www.chem.wisc.edu/areas/organic/studsemin/steinkruger/steinkruger-sem.pdf.
- ↑ Eliot, Andrew C.; Kirsch, Jack F. (June 2004). "Pyridoxal Phosphate Enzymes: Mechanistic, Structural, and Evolutionary Considerations" (in en). Annual Review of Biochemistry 73 (1): 383–415. doi:10.1146/annurev.biochem.73.011303.074021. PMID 15189147. https://www.life.illinois.edu/biochem/455/Lab%20exercises/5GOT/PLP%20enzyme%20review.pdf. Retrieved 9 November 2022.
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