Remarkable destabilization of recombinant alpha-lactalbumin by an extraneous N-terminal methionyl residue.
A recombinant bovine alpha-lactalbumin, possessing an additional N-terminal methionyl residue, was expressed in Escherichia coli. In order to address the effects of the N-terminal methionyl residue on conformational stability, the thermal stability of the recombinant alpha-lactalbumin was investigated by measuring temperature-dependence of circular dichroism spectra, and it was compared with that of authentic alpha-lactalbumin from bovine milk. The thermal stability of the recombinant alpha-lactalbumin was significantly lower than that of authentic alpha-lactalbumin. The enthalpy change of unfolding of the recombinant protein was found to be the same as that of the authentic one when compared at the same temperature. Therefore, the N-terminal methionyl residue seems to destabilize the conformation of recombinant alpha-lactalbumin through some entropic effects.
Department of Bioengineering, Faculty of Engineering, Soka University, Tokyo, Japan.
N
N
Ishikawa
T
T
Chiba
L T
LT
Chen
A
A
Shimizu
M
M
Ikeguchi
S
S
Sugai
D000818:Animals; D002417:Cattle; D002942:Circular Dichroism; D019277:Entropy; D004926:Escherichia coli / Q000235:genetics; D007768:Lactalbumin / Q000096:biosynthesis / Q000737:chemistry* / Q000235:genetics; D008715:Methionine; D011487:Protein Conformation; D011489:Protein Denaturation; D017510:Protein Folding; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000737:chemistry* / Q000235:genetics
D011994:Recombinant Proteins; D007768:Lactalbumin; D008715:Methionine