Polarographische Kennzeichnung organischer Strukturtypen. I. Mitteilung: Unterscheidung zwischen Indolen, Indoleninen und α‐Methylen‐dihydroindolen

Abstract

B2HZ-NC Die Polarographie als Test auf die Strukturen 1-111 hat sich in unseren Untersuchungen an S t r y c h n o s -A lk a l o i d e n bereits bewahrt; hieriiber wird anderweitig berlchtet. Das Verfahren verspricht, besonders da es sich um eine ausgesprochene Mikromethode handelt, eine entsprechende Charakterisierung auch von Calebassen-Curare3) zu ernloglichen. 293

Organic Polarography

“…Polarographic studies are reported for -pyrrole aldehyde (54) and of-methylenedihydroindole (97). The reduction reported in the latter paper for V-vinylcarbazole may be due to peroxides.…”

Influence of M subunit Thr222 and Trp252 on quinone binding and electron transfer in Rhodobacter sphaeroides reaction centres

“…The electrochemical reduction potential of tryptophan has not been determined. However, from the values of corresponding organic molecules, the reduction potential of tryptophan in polar solutions can be estimated to lie between l .7 and -2.0 eV (Ender et al, 1954;Volke, 1963). Besides, tryptophan M252 could accelerate the electron-transfer via the so-called superexchange mechanism (Michel-Beyerle et al, 1988 ;Halpern and Orgel, 1960;McConnell, 1961 ;Larsson, 1981 ;Miller and Beitz, 1981;Beratan et al, 1985).…”

“…sphaeroides shows a hydrogen bond from threonine M222 to the quionone QA and not to the tryptophan M252. However, another previously published structure (Allen et al, 1988) and the recent high resolution (0.23 nm) structure (Buchanan et al, 1993;Ermler et al, 1992; H. Michel, unpublished results) indicate that the hydrogen bridge is di- Fig. 1.…”

“…Recently, a high resolution structure for Rb. sphaeroides was also reported and a high degree of structural similarity be-tween the two reaction centres was revealed (Buchanan et al, 1993;Ermler et al, 1992).…”