Napin from Brassica juncea: thermodynamic and structural analysis of stability.


The napin from Brassica juncea, oriental mustard, is highly thermostable, proteolysis resistant and allergenic in nature. It consists of two subunits - one small (29 amino acid residues) and one large (86 amino acids residues) - held together by disulfide bonds. The thermal unfolding of napin has been followed by differential scanning calorimetry (DSC) and circular dichroism (CD) measurements. The thermal unfolding is characterized by a three state transition with T(M1) and T(M2) at 323.5 K and 335.8 K, respectively; DeltaC(P1) and DeltaC(P2) are 2.05 kcal mol(-1) K(-1) and 1.40 kcal mol(-1) K(-1), respectively. In the temperature range 310-318 K, the molecule undergoes dimerisation. Isothermal equilibrium unfolding by guanidinium hydrochloride also follows a three state transition, N <_-_-> I <_-_-> U with DeltaG(1H2O) and DeltaG(2H2O) values of 5.2 kcal mol(-1) and 5.1 kcal mol(-1) at 300 K, respectively. Excess heat capacity values obtained, are similar to those obtained from DSC measurements. There is an increase in hydrodynamic radius from 20 A to 35.0 A due to unfolding by guanidinium hydrochloride. In silico alignment of sequences of napin has revealed that the internal repeats (40%) spanning residues 31 to 60 and 73 to 109 are conserved in all Brassica species. The internal repeats may contribute to the greater stability of napin. A thorough understanding of the structure and stability of these proteins is essential before they can be exploited for genetic improvements for nutrition. Study holds ProTherm entries: 23040, 23041, 23042, 23043, 23044, 23045, 23046, 23047, 23048, 23049, 23050, 23051, 23052, 23053, 23054, 23055, 23056, 23057, 23058, 23059 Extra Details: The scan rate was 60K/h; Transition 1 Napin; Thermal stability; Brassica juncea; Association; Protein unfolding; Internal repeats

Submission Details

ID: 9pNKbuGL4

Submitter: Connie Wang

Submission Date: April 24, 2018, 8:54 p.m.

Version: 1

Publication Details
Jyothi TC;Sinha S;Singh SA;Surolia A;Appu Rao AG,Biochim. Biophys. Acta (2007) Napin from Brassica juncea: thermodynamic and structural analysis of stability. PMID:17544981
Additional Information

Study Summary

Number of data points 56
Proteins Napin-1A ; Napin-1A
Unique complexes 1
Assays/Quantities/Protocols Experimental Assay: m prot_conc:0.12 mg/mL ; Experimental Assay: dG_H2O prot_conc:0.12 mg/mL ; Experimental Assay: m prot_conc:0.4-2.5 mg/mL ; Experimental Assay: dG_H2O prot_conc:0.4-2.5 mg/mL ; Experimental Assay: dHcal prot_conc:106 microM ; Experimental Assay: Tm prot_conc:106 microM ; Experimental Assay: dHvH prot_conc:106 microM ; Experimental Assay: dHcal prot_conc:92 microM ; Experimental Assay: Tm prot_conc:92 microM ; Experimental Assay: dHvH prot_conc:92 microM ; Experimental Assay: dHcal prot_conc:75 microM ; Experimental Assay: Tm prot_conc:75 microM ; Experimental Assay: dHvH prot_conc:75 microM ; Experimental Assay: dHcal prot_conc:65 microM ; Experimental Assay: Tm prot_conc:65 microM ; Experimental Assay: dHvH prot_conc:65 microM ; Experimental Assay: dHcal prot_conc:50 microM ; Experimental Assay: Tm prot_conc:50 microM ; Experimental Assay: dHvH prot_conc:50 microM ; Experimental Assay: dHcal prot_conc:40 microM ; Experimental Assay: Tm prot_conc:40 microM ; Experimental Assay: dHvH prot_conc:40 microM ; Experimental Assay: dHcal prot_conc:25 microM ; Experimental Assay: Tm prot_conc:25 microM ; Experimental Assay: dHvH prot_conc:25 microM ; Experimental Assay: dHcal prot_conc:10 microM ; Experimental Assay: Tm prot_conc:10 microM ; Experimental Assay: dHvH prot_conc:10 microM

Structure view and single mutant data analysis

Study data

No weblogo for data of varying length.
Colors: D E R H K S T N Q A V I L M F Y W C G P

Data Distribution

Studies with similar sequences (approximate matches)

Correlation with other assays (exact sequence matches)

Relevant PDB Entries

Structure ID Release Date Resolution Structure Title

Relevant UniProtKB Entries

Percent Identity Matching Chains Protein Accession Entry Name
198.7 A,B Napin-1A P24565 2SSI_BRANA