Anomalies in the refinement of isoleucine. (1st April 2014)

• Record Type: Journal Article
• Authors: Berntsen, Karen R. M.; Vriend, Gert
• Is Part Of: Acta crystallographica. Volume 70:Part 4(2014:Apr.)
• Page Start: 1037
• Page End: 1049
• Publication Date: 2014-04-01
• Subjects: Biomolecules -- Structure -- Periodicals; Physical biochemistry -- Periodicals; X-ray crystallography -- Periodicals; Crystallography -- Periodicals; 572
• DOI: 10.1107/S139900471400087X
• Languages: English
• ISSNs: 0907-4449

Abstract

<abstract abstract-type="main" xml:lang="en"> <title> <x xml:space="preserve">Abstract</x> </title> <p>A study of isoleucines in protein structures solved using X‐ray crystallography revealed a series of systematic trends for the two side‐chain torsion angles χ₁ and χ₂ dependent on the resolution, secondary structure and refinement software used. The average torsion angles for the nine rotamers were similar in high‐resolution structures solved using either the <italic>REFMAC</italic>, <italic>CNS</italic> or <italic>PHENIX</italic> software. However, at low resolution these programs often refine towards somewhat different χ₁ and χ₂ values. Small systematic differences can be observed between refinement software that uses molecular dynamics‐type energy terms (for example <italic>CNS</italic>) and software that does not use these terms (for example <italic>REFMAC</italic>). Detailing the standard torsion angles used in refinement software can improve the refinement of protein structures. The target values in the molecular dynamics‐type energy functions can also be improved.</p> </abstract>