A structural comparison of three isoforms of anionic trypsin from chum salmon (Oncorhynchus keta)

Abstract

Three anionic salmon trypsin isoforms (CST-1, CST-2 and CST-3) were isolated from the pyloric caeca of chum salmon (Oncorhynchus keta). The order of catalytic efficiency (K(m)/k(cat)) of the isoforms during BAPA hydrolysis was CST-2 > CST-1 > CST-3. In order to find a structural rationalization for the observed difference in catalytic efficiency, the X-ray crystallographic structures of the three isoforms were compared in detail. Some structural differences were observed in the C-terminal alpha-helix, interdomain loop and active-site region. From the results of the detailed comparison, it appears that the structural flexibility of the C-terminal alpha-helix, which interacts with the N-terminal domain, and the substrate-binding pocket in CST-3 are lower than those in CST-1 and CST-2. In addition, the conformation of the catalytic triad (His57, Asp102 and Ser195) differs among the three isoforms. The imidazole N atom of His57 in CST-1 and CST-2 forms a hydrogen bond to the hydroxyl O atom of Ser195, but the distance between the imidazole N atom of His57 and the hydroxyl O atom of Ser195 in CST-3 is too great (3.8 A) for the formation of a hydrogen bond. Thus, the nucleophilicity of the hydroxyl group of Ser195 in CST-3 is weaker than that in CST-1 or CST-2. Furthermore, the electrostatic potential of the substrate-binding pocket in CST-2 is markedly lower than those in CST-1 and CST-3 owing to the negative charges of Asp150, Asp153 and Glu221B that arise from the long-range effect. These results may explain the higher catalytic efficiency of CST-2 compared with CST-1 and CST-3.

Elucidation of different cold-adapted Atlantic cod ( Gadus morhua ) trypsin X isoenzymes

“…As to why this variability is found within trypsinogen X like sequences but not within trypsinogen I is not known. The presence of multiple trypsinogen genes within a genome, six for example in Senegalese sole (Solea senegalensis), has been reported in other fish species [28][29][30][31][32]. In Atlantic salmon three trypsins (SalTRP-I, SalTRP-IA and SalTRP-IB) with very similar sequences were identified [32].…”

Molecular mechanism analysis of Gloydius shedaoensis venom gloshedobin interaction with inhibitors by homology modeling

“…However, compared with salt bonds, hydrogen bond is relatively weaker, so BMD has little impact on the enzyme catalytic efficiency. The structure of trypsin complexed with BMD suggests that BMD interacts with residues Asp189, Ser190 and Gly217, the same way as for ACC-C [27].…”

Culex quinquefasciatus Late Trypsin Biosynthesis Is Translationally Regulated by Trypsin Modulating Oostatic Factor

“…Homology modeling of the C. quinquefasciatus late pro-trypsin was performed with the YASARA Structure program ( Krieger et al, 2002 ). Different templates of pro-trypsin were used to build the pro-trypsin model using the atomic coordinates of trypsin-1 from the Atlantic salmon ( Salmo salar ) (PDB code 1HJ8 and 1UTJ) ( Leiros et al, 2001 , 2004 ), anionic trypsin (PDB code 2ZPQ), cationic trypsin isoform 2 (PDB code 2ZPR), and anionic trypsin isoform 3 (PDB code 2ZPS) from the chum salmon ( Oncorhynchus keta ) ( Toyota et al, 2009 ). The model that was built using 2ZPR, contained 233 amino acid residues (7–240), exhibited a better Z -score, and was saved as the final model for the late C. quinquefasciatus pro-trypsin.…”