### Abstract

The bacteriorhodopsin photocycle contains more than five spectrally distinct intermediates, and the complexity of the interconversions has precluded a rigorous solution of the kinetics. A representation of the photocycle of mutated D96N bacteriorhodopsin near neutral pH was given earlier (Varo, G., and J. K. Lanyi. 1991. Biochemistry. 30:5008-5015) as BR→(hv)→K⇆L⇆M_{1}→M_{2}→BR. Here we have reduced a set of time-resolved difference spectra for this simpler system to three base spectra, each assumed to consist of an unknown mixture of the pure K, L, and M difference spectra represented by a 3x3 matrix of concentration values between 0 and 1. After generating all allowed sets of spectra for K, L, and M (i.e., M_{1} + M_{2}) at a 1:50 resolution of the matrix elements, invalid solutions were eliminated progressively in a search based on what is expected, empirically and from the theory of polyene excited states, for rhodopsin spectra. Significantly, the average matrix values changed little after the first and simplest of the search criteria that disallowed negative absorptions and more than one maximum for the M intermediate. We conclude from the statistics that during the search the solutions strongly converged into a narrow region of the multidimensional space of the concentration matrix. The data at three temperatures between 5 and 25°C yielded a single set of spectra for K, L, and M; their fits are consistent with the earlier derived photocycle model for the D96N protein.

Original language | English |
---|---|

Pages (from-to) | 240-251 |

Number of pages | 12 |

Journal | Biophysical Journal |

Volume | 64 |

Issue number | 1 |

Publication status | Published - 1993 |

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### ASJC Scopus subject areas

- Biophysics

### Cite this

**Deriving the intermediate spectra and photocycle kinetics from time-resolved difference spectra of bacteriorhodopsin : The simpler case of the recombinant D96N protein.** / Zimányi, L.; Lanyi, J. K.

Research output: Contribution to journal › Article

*Biophysical Journal*, vol. 64, no. 1, pp. 240-251.

}

TY - JOUR

T1 - Deriving the intermediate spectra and photocycle kinetics from time-resolved difference spectra of bacteriorhodopsin

T2 - The simpler case of the recombinant D96N protein

AU - Zimányi, L.

AU - Lanyi, J. K.

PY - 1993

Y1 - 1993

N2 - The bacteriorhodopsin photocycle contains more than five spectrally distinct intermediates, and the complexity of the interconversions has precluded a rigorous solution of the kinetics. A representation of the photocycle of mutated D96N bacteriorhodopsin near neutral pH was given earlier (Varo, G., and J. K. Lanyi. 1991. Biochemistry. 30:5008-5015) as BR→(hv)→K⇆L⇆M1→M2→BR. Here we have reduced a set of time-resolved difference spectra for this simpler system to three base spectra, each assumed to consist of an unknown mixture of the pure K, L, and M difference spectra represented by a 3x3 matrix of concentration values between 0 and 1. After generating all allowed sets of spectra for K, L, and M (i.e., M1 + M2) at a 1:50 resolution of the matrix elements, invalid solutions were eliminated progressively in a search based on what is expected, empirically and from the theory of polyene excited states, for rhodopsin spectra. Significantly, the average matrix values changed little after the first and simplest of the search criteria that disallowed negative absorptions and more than one maximum for the M intermediate. We conclude from the statistics that during the search the solutions strongly converged into a narrow region of the multidimensional space of the concentration matrix. The data at three temperatures between 5 and 25°C yielded a single set of spectra for K, L, and M; their fits are consistent with the earlier derived photocycle model for the D96N protein.

AB - The bacteriorhodopsin photocycle contains more than five spectrally distinct intermediates, and the complexity of the interconversions has precluded a rigorous solution of the kinetics. A representation of the photocycle of mutated D96N bacteriorhodopsin near neutral pH was given earlier (Varo, G., and J. K. Lanyi. 1991. Biochemistry. 30:5008-5015) as BR→(hv)→K⇆L⇆M1→M2→BR. Here we have reduced a set of time-resolved difference spectra for this simpler system to three base spectra, each assumed to consist of an unknown mixture of the pure K, L, and M difference spectra represented by a 3x3 matrix of concentration values between 0 and 1. After generating all allowed sets of spectra for K, L, and M (i.e., M1 + M2) at a 1:50 resolution of the matrix elements, invalid solutions were eliminated progressively in a search based on what is expected, empirically and from the theory of polyene excited states, for rhodopsin spectra. Significantly, the average matrix values changed little after the first and simplest of the search criteria that disallowed negative absorptions and more than one maximum for the M intermediate. We conclude from the statistics that during the search the solutions strongly converged into a narrow region of the multidimensional space of the concentration matrix. The data at three temperatures between 5 and 25°C yielded a single set of spectra for K, L, and M; their fits are consistent with the earlier derived photocycle model for the D96N protein.

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M3 - Article

VL - 64

SP - 240

EP - 251

JO - Biophysical Journal

JF - Biophysical Journal

SN - 0006-3495

IS - 1

ER -