Characterization and In-Silico studies on ubiquitin protein from seeds of Sisymbrium irio

Ubiquitin protein was identified and characterized from the seeds of sisymbrium (s.) irio. results of lc-ms/ms spectrometry revealed that s. irio ubiquitin (siu) shares around 77% sequence identity with already reported ubiquitin proteins from triticum aestivum,avena sativa,arabidopsis thaliana and others. siu revealed a molecular weight of 17 kda on non-reduced sds-page while a reduced band of approximately 9 kda in the presence of β-mercaptoethanol. a pi of 9.2 was calculated by isoelectric focusing measurement. circular dichroism (cd) spectroscopic studies showed that the secondary structure of siu comprised of about 6.5% α-helix,39.3% β-sheet,0.7% turn,53.5% random coil which indicates that it is mostly β-sheeted. similarly,a hydrodynamic radius (rh) of 2.44 nm was calculated by dynamic light scattering (dls) for monodispersive siu which further infers the presence of a dimeric status of 9 kda native protein in solution. multiple sequence alignment of 20 different ubiquitin sequences revealed that ubiquitin sequence is well conserved in nature with very few amino acid differences,e.g. r42k,q49d,and q62d. homology modeling of siu (11-28,and 42-76) residues suggested overall conserved secondary and tertiary conformation and other structural motifs. this report describes the purification,characterization and structural analysis of an ubiquitin protein from seeds of s.