A state of an atom or group which, due to its binding in a protein, has its geometric or electronic condition adapted for function.
Note:
It is derived from entasis (Greek), meaning tension.
Source:
PAC, 1997, 69, 1251. 'Glossary of terms used in bioinorganic chemistry (IUPAC Recommendations 1997)' on page 1272 (https://doi.org/10.1351/pac199769061251)