Schick G A, Cooper T M, Holloway R A, Murray L P, Birge R R
Biochemistry. 1987 May 5;26(9):2556-62. doi: 10.1021/bi00383a022.
The energetics associated with the photoequilibrium (Formula: see text) are measured at 77 K by using pulsed-laser photocalorimetry and a range of excitation wavelengths and relative starting concentrations. Enthalpies for the photochemical transformations R hv----B and I hv----B are measured to be delta HRB = 32.2 +/- 0.9 kcal mol-1 and delta HIB = 27.1 +/- 3.2 kcal mol-1, respectively. Although the value of delta HRB is slightly lower than that reported previously by Cooper of 34.7 +/- 2.2 kcal mol-1 [Cooper, A. (1979) Nature (London) 282, 531-533], the two values are in agreement within experimental error. The energy difference delta HRB - delta HIB = 5.1 +/- 3.3 kcal mol-1 is identical within experimental error with the difference in enthalpies of isorhodopsin and rhodopsin [5.2 +/- 2.3; Cooper, A. (1979) FEBS Lett. 100, 382-384]. We suggest that this result is consistent with the theory that bathorhodopsin is a single, common photochemical intermediate connecting rhodopsin and isorhodopsin.
通过使用脉冲激光光量热法以及一系列激发波长和相对起始浓度，在77K下测量与光平衡相关的能量学（公式：见正文）。光化学转化R hv----B和I hv----B的焓分别测得为ΔHRB = 32.2±0.9 kcal mol-1和ΔHIB = 27.1±3.2 kcal mol-1。尽管ΔHRB的值略低于库珀之前报道的34.7±2.2 kcal mol-1 [库珀，A.（1979年）《自然》（伦敦）282，531 - 533]的值，但这两个值在实验误差范围内是一致的。能量差ΔHRB - ΔHIB = 5.1±3.3 kcal mol-1在实验误差范围内与异视紫红质和视紫红质的焓差[5.2±2.3；库珀，A.（1979年）《欧洲生物化学学会联合会快报》100，382 - 384]相同。我们认为这一结果与视紫红质中间体是连接视紫红质和异视紫红质的单一常见光化学中间体的理论一致。
