Premium
Three‐dimensional structure of bovine pancreatic DNase I at 2.5 A resolution.
Author(s) -
Suck D.,
Oefner C.,
Kabsch W.
Publication year - 1984
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1002/j.1460-2075.1984.tb02149.x
Subject(s) - crystallography , biology , deoxyribonuclease , nuclease , resolution (logic) , deoxyribonuclease i , protein structure , crystallization , dna , stereochemistry , biochemistry , chemistry , artificial intelligence , computer science , base sequence , organic chemistry
The three‐dimensional structure of bovine pancreatic deoxyribonuclease I (DNase I) has been determined at 2.5 A resolution by X‐ray diffraction from single crystals. An atomic model was fitted into the electron density using a graphics display system. DNase I is an alpha, beta‐protein with two 6‐stranded beta‐pleated sheets packed against each other forming the core of a ‘sandwich’‐type structure. The two predominantly anti‐parallel beta‐sheets are flanked by three longer alpha‐helices and extensive loop regions. The carbohydrate side chain attached to Asn 18 is protruding by approximately 15 A from the otherwise compact molecule of approximate dimensions 45 A X 40 A. The binding site of CA2+‐deoxythymidine‐3′,5′‐biphosphate (Ca‐pdTp) has been determined by difference Fourier techniques confirming biochemical results that the active centre is close to His 131. Ca‐pdTp binds at the surface of the enzyme between the two beta‐pleated sheets and seems to interact with several charged amino acid side chains. Active site geometry and folding pattern of DNase I are quite different from staphylococcal nuclease, the only other Ca2+‐dependent deoxyribonuclease whose structure is known at high resolution. The electron density map indicates that two Ca2+ ions are bound to the enzyme under crystallization conditions.