Trigonal Bipyramidal Zinc Center

One of the possible geometries for zinc in proteins is trigonal bipyramidal. Trigonal bipyramidal geometry involves the central atom being surrounded by five atoms: two axial and three equatorial.

Adenosine deaminase is important in the purine metabolic pathway. It is also
important in immune system maintenance. This enzyme catalyzes the irreversible
deamination of adenosine and 2'-deoxyadenosine. An interesting thing about
this enzyme is that it produces a reaction rate increase on the order of 1012
when compared to the reaction without the enzyme.1 The average axial bond
distance is 214 pm, and the average equatorial bond distance is 226 pm.

1Sideraki, V., Wilson, D., Kurz, L., Quiocho, F., Rudolph, F. Biochemistry 1996, 35, 15019.

Enolase, or 2-phospho-D-glycerate hydrolase, is an important enzyme in glycolysis,
the breakdown of glucose and the formation of ATP and NADH. It catalyzes the elimination of water
from 2-phosphoglyceric acid to make phosphoenolpyruvate, the only dehydration reaction in
glycolysis. Enolase is activated by Mg(II) and Zn(II) and inhibited by phosphoglycolate.2
The average axial bond distance is 213 pm, and the average equatorial bond distance is 195 pm.

2Lebioda, L., Stec, B., Brewer, J., Tykarska, E. Biochemistry 1991, 30, 2823.

Tetrahedral Zinc
Trigonal Pyramidal Zinc
Two Other Zinc Structures

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