PDBsum entry 2fd7

Unknown function

PDB id: 2fd7

Contents

Protein chain

46 a.a. *

Waters ×83

* Residue conservation analysis

PDB id:

2fd7

Name:

Unknown function

Title:

X-ray crystal structure of chemically synthesized crambin

Structure:

Crambin. Chain: a. Engineered: yes

Source:

Synthetic: yes. Other_details: the protein was chemically synthesized. The sequence of the protein can be naturally found in crambe abyssinica (abyssinian crambe).

Resolution:

1.75Å R-factor: 0.160 R-free: 0.185

Authors:

D.Bang,V.Tereshko,A.A.Kossiakoff,S.B.Kent

Key ref:

D.Bang et al. (2009). Role of a salt bridge in the model protein crambin explored by chemical protein synthesis: X-ray structure of a unique protein analogue, [V15A]crambin-alpha-carboxamide. Mol Biosyst, 5, 750-756. PubMed id: 19562114

Date:

13-Dec-05 Release date: 16-Jan-07

Protein chain

P01542  (CRAM_CRAAB) -  Crambin from Crambe hispanica subsp. abyssinica

Seq: 46 a.a.

Struc: 46 a.a.

Mol Biosyst 5:750-756 (2009)

PubMed id: 19562114

Role of a salt bridge in the model protein crambin explored by chemical protein synthesis: X-ray structure of a unique protein analogue, [V15A]crambin-alpha-carboxamide.

D.Bang, V.Tereshko, A.A.Kossiakoff, S.B.Kent.

ABSTRACT

We have used total chemical synthesis to prepare [V15A]crambin-alpha-carboxamide, a unique protein analogue that eliminates a salt bridge between the delta-guanidinium of the Arg(10) side chain and the alpha-carboxylate of Asn(46) at the C-terminus of the polypeptide chain. This salt bridge is thought to be important for the folding and stability of the crambin protein molecule. Folding, with concomitant disulfide bond formation, of the fully reduced [V15A]crambin-alpha-carboxamide polypeptide was less efficient than folding/disulfide formation for the [V15A]crambin polypeptide under a standard set of conditions. To probe the origin of this less efficient folding/disulfide bond formation, we separately crystallized purified synthetic [V15A]crambin-alpha-carboxamide and chemically synthesized [V15A]crambin and solved their X-ray structures. The crystal structure of [V15A]crambin-alpha-carboxamide showed that elimination of the Arg(10)-Asn(46) salt bridge caused disorder of the C-terminal region of the polypeptide chain and affected the overall 'tightness' of the structure of the protein molecule. These studies, enabled by chemical protein synthesis, strongly suggest that in native crambin the Arg(10)-Asn(46) salt bridge contributes to efficient formation of correct disulfide bonds and also to the well-ordered structure of the protein molecule.