Purple membrane

Color, crystallinity, and the effect of dimethyl sulfoxide

C. Pande, Robert Callender, R. Henderson, A. Pande

Research output: Contribution to journalArticle

14 Citations (Scopus)

Abstract

In an effort to understand the nature of chromophore-protein interactions in bacteriorhodopsin (bR), we have reinvestigated dimethyl sulfoxide (DMSO)-induced changes in bR [Oesterhelt et al. (1973) Eur. J. Biochem. 40, 453-463]. We observe that dark-adapted bR (bR560) in aqueous DMSO undergoes reversible transformation to a species absorbing maximally at 480 nm (bR480). Beginning at 40% DMSO, this change results in complete conversion to bR480 at 60% DMSO. The kinetics of the reaction reveal that this transformation takes place predominantly through the all-trans isomeric form of the pigment. Thermal isomerization of the 13-cis chromophore to the all-trans form is, therefore, the rate-limiting step in the formation of bR480 from the dark-adapted bR. As in native bR, the chromophore in bR480 is linked to the protein via a protonated Schiff base, and its isomeric composition is predominantly all-trans. The formation of bR480 is associated with minor changes in the protein secondary structure, and the membrane retains crystallinity. These changes in the protein structure result in a diminished chromophore-protein interaction near the Schiff base region in bR480. Thus, we attribute the observed spectroscopic changes in bR in DMSO to structural alteration of the protein. The 13-cis chromophoric pigment appears to be resistant to this solvent-induced change. The changes in the protein structure need not be very large; displacement of the protein counterion(s) to the Schiff base, resulting from minor changes in the protein structure, can produce the observed spectral shift.

Original languageEnglish (US)
Pages (from-to)5971-5978
Number of pages8
JournalBiochemistry
Volume28
Issue number14
StatePublished - 1989
Externally publishedYes

Fingerprint

Purple Membrane
Dimethyl Sulfoxide
Bacteriorhodopsins
Color
Membranes
Chromophores
Schiff Bases
Proteins
Pigments
Secondary Protein Structure
Isomerization
Hot Temperature

ASJC Scopus subject areas

  • Biochemistry

Cite this

Pande, C., Callender, R., Henderson, R., & Pande, A. (1989). Purple membrane: Color, crystallinity, and the effect of dimethyl sulfoxide. Biochemistry, 28(14), 5971-5978.

Purple membrane : Color, crystallinity, and the effect of dimethyl sulfoxide. / Pande, C.; Callender, Robert; Henderson, R.; Pande, A.

In: Biochemistry, Vol. 28, No. 14, 1989, p. 5971-5978.

Research output: Contribution to journalArticle

Pande, C, Callender, R, Henderson, R & Pande, A 1989, 'Purple membrane: Color, crystallinity, and the effect of dimethyl sulfoxide', Biochemistry, vol. 28, no. 14, pp. 5971-5978.
Pande, C. ; Callender, Robert ; Henderson, R. ; Pande, A. / Purple membrane : Color, crystallinity, and the effect of dimethyl sulfoxide. In: Biochemistry. 1989 ; Vol. 28, No. 14. pp. 5971-5978.
@article{3942e099150e42969280b447c641e0a7,
title = "Purple membrane: Color, crystallinity, and the effect of dimethyl sulfoxide",
abstract = "In an effort to understand the nature of chromophore-protein interactions in bacteriorhodopsin (bR), we have reinvestigated dimethyl sulfoxide (DMSO)-induced changes in bR [Oesterhelt et al. (1973) Eur. J. Biochem. 40, 453-463]. We observe that dark-adapted bR (bR560) in aqueous DMSO undergoes reversible transformation to a species absorbing maximally at 480 nm (bR480). Beginning at 40{\%} DMSO, this change results in complete conversion to bR480 at 60{\%} DMSO. The kinetics of the reaction reveal that this transformation takes place predominantly through the all-trans isomeric form of the pigment. Thermal isomerization of the 13-cis chromophore to the all-trans form is, therefore, the rate-limiting step in the formation of bR480 from the dark-adapted bR. As in native bR, the chromophore in bR480 is linked to the protein via a protonated Schiff base, and its isomeric composition is predominantly all-trans. The formation of bR480 is associated with minor changes in the protein secondary structure, and the membrane retains crystallinity. These changes in the protein structure result in a diminished chromophore-protein interaction near the Schiff base region in bR480. Thus, we attribute the observed spectroscopic changes in bR in DMSO to structural alteration of the protein. The 13-cis chromophoric pigment appears to be resistant to this solvent-induced change. The changes in the protein structure need not be very large; displacement of the protein counterion(s) to the Schiff base, resulting from minor changes in the protein structure, can produce the observed spectral shift.",
author = "C. Pande and Robert Callender and R. Henderson and A. Pande",
year = "1989",
language = "English (US)",
volume = "28",
pages = "5971--5978",
journal = "Biochemistry",
issn = "0006-2960",
publisher = "American Chemical Society",
number = "14",

}

TY - JOUR

T1 - Purple membrane

T2 - Color, crystallinity, and the effect of dimethyl sulfoxide

AU - Pande, C.

AU - Callender, Robert

AU - Henderson, R.

AU - Pande, A.

PY - 1989

Y1 - 1989

N2 - In an effort to understand the nature of chromophore-protein interactions in bacteriorhodopsin (bR), we have reinvestigated dimethyl sulfoxide (DMSO)-induced changes in bR [Oesterhelt et al. (1973) Eur. J. Biochem. 40, 453-463]. We observe that dark-adapted bR (bR560) in aqueous DMSO undergoes reversible transformation to a species absorbing maximally at 480 nm (bR480). Beginning at 40% DMSO, this change results in complete conversion to bR480 at 60% DMSO. The kinetics of the reaction reveal that this transformation takes place predominantly through the all-trans isomeric form of the pigment. Thermal isomerization of the 13-cis chromophore to the all-trans form is, therefore, the rate-limiting step in the formation of bR480 from the dark-adapted bR. As in native bR, the chromophore in bR480 is linked to the protein via a protonated Schiff base, and its isomeric composition is predominantly all-trans. The formation of bR480 is associated with minor changes in the protein secondary structure, and the membrane retains crystallinity. These changes in the protein structure result in a diminished chromophore-protein interaction near the Schiff base region in bR480. Thus, we attribute the observed spectroscopic changes in bR in DMSO to structural alteration of the protein. The 13-cis chromophoric pigment appears to be resistant to this solvent-induced change. The changes in the protein structure need not be very large; displacement of the protein counterion(s) to the Schiff base, resulting from minor changes in the protein structure, can produce the observed spectral shift.

AB - In an effort to understand the nature of chromophore-protein interactions in bacteriorhodopsin (bR), we have reinvestigated dimethyl sulfoxide (DMSO)-induced changes in bR [Oesterhelt et al. (1973) Eur. J. Biochem. 40, 453-463]. We observe that dark-adapted bR (bR560) in aqueous DMSO undergoes reversible transformation to a species absorbing maximally at 480 nm (bR480). Beginning at 40% DMSO, this change results in complete conversion to bR480 at 60% DMSO. The kinetics of the reaction reveal that this transformation takes place predominantly through the all-trans isomeric form of the pigment. Thermal isomerization of the 13-cis chromophore to the all-trans form is, therefore, the rate-limiting step in the formation of bR480 from the dark-adapted bR. As in native bR, the chromophore in bR480 is linked to the protein via a protonated Schiff base, and its isomeric composition is predominantly all-trans. The formation of bR480 is associated with minor changes in the protein secondary structure, and the membrane retains crystallinity. These changes in the protein structure result in a diminished chromophore-protein interaction near the Schiff base region in bR480. Thus, we attribute the observed spectroscopic changes in bR in DMSO to structural alteration of the protein. The 13-cis chromophoric pigment appears to be resistant to this solvent-induced change. The changes in the protein structure need not be very large; displacement of the protein counterion(s) to the Schiff base, resulting from minor changes in the protein structure, can produce the observed spectral shift.

UR - http://www.scopus.com/inward/record.url?scp=0024967187&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0024967187&partnerID=8YFLogxK

M3 - Article

VL - 28

SP - 5971

EP - 5978

JO - Biochemistry

JF - Biochemistry

SN - 0006-2960

IS - 14

ER -