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Structure of anionic salmon trypsin in a second crystal form.
G I Berglund1, A O Smalås, A Hordvik
1Protein Crystallography Group, Department of Chemistry, Institute of Mathematical and Physical Sciences, University of Tromsø, Norway.
Acta Crystallographica. Section D, Biological Crystallography
|September 1, 1995
Summary
This study details a new crystal form of anionic salmon trypsin (ST-IIB), revealing differences in sulfate and benzamidine binding compared to a previous form (ST-IIA). Structural analysis provides insights into salmon trypsin
Area of Science:
- Biochemistry
- Structural Biology
- Crystallography
Background:
- Anionic salmon trypsin is a key enzyme with various biological roles.
- Understanding its structure is crucial for biochemical and pharmaceutical applications.
- Previous structural data exists for salmon trypsin in a different crystal form (ST-IIA).
Purpose of the Study:
- To refine and characterize a second crystal form of anionic salmon trypsin (ST-IIB).
- To compare the ST-IIB structure with the previously reported ST-IIA form.
- To identify structural differences and their potential implications.
Main Methods:
- X-ray crystallography was used to determine the structure of ST-IIB.
- The crystal structure was refined at 1.83 A resolution.
- The new structure was compared to the previously determined ST-IIA structure using superposition analysis.
Main Results:
- The ST-IIB crystals are orthorhombic (space group P2(1)2(1)2) with specific lattice parameters.
- Striking differences include a sulfate group forming hydrogen bonds to active-site residues and an additional benzamidine site.
- Superposition of main-chain atoms revealed an overall r.m.s. difference of 0.26 A, with variations attributed to molecular packing.
- The overall coordinate error was estimated between 0.20 and 0.25 A.
Conclusions:
- The ST-IIB crystal form presents distinct structural features compared to ST-IIA.
- The identified differences, particularly involving sulfate and benzamidine, may influence enzyme activity or interactions.
- This refined structural data enhances our understanding of anionic salmon trypsin's molecular architecture.