Nuclear-magnetic-resonance investigations of the biliverdin-apomyoglobin complex

The recently described biliverdin-apomyoglobin complex has been investigated by two-dimensional NMR methods and molecular modeling with respect to the geometry of the chromophore and its position within the myoglobin pocket. Nuclear Overhauser effect correlations between the ligand and apoprotein amino acid residues prove that the bile pigment assumes a cyclic helical conformation and a position similar to heme in native myoglobin.

Applications of ultrafast laser spectroscopy for the study of biological systems

The discovery of mode-locked laser operation now nearly two decades ago has started a development which enables researchers to probe the dynamics of ultrafast physical and chemical processes at the molecular level on shorter and shorter time scales. Naturally the first applications were in the fields of photophysics and photochemistry where it was then possible for the first time to probe electronic and vibrational relaxation processes on a sub-nanosecond timescale. The development went from lasers producing pulses of many picoseconds to the shortest pulses which are at present just a few femtoseconds long. Soon after their discovery ultrashort pulses were applied also to biological systems which has revealed a wealth of information contributing to our understanding of a broadrange of biological processes on the molecular level.It is the aim of this review to discuss the recent advances and point out some future trends in the study of ultrafast processes in biological systems using laser techniques. The emphasis will be mainly on new results obtained during the last 5 or 6 years. The term ultrafast means that I shall restrict myself to sub-nanosecond processes with a few exceptions.

Biliverdin IX delta and neobiliverdin IX delta, isolated from the ovaries of the marine snail, Turbo cornutus

The ovaries of the marine snail Turbo cornutus contain a number of pigments. So far, the presence of carotenoids and a chromoprotein with a bile pigment, called turboverdin (= 3(2)-hydroxy-mesobiliverdin IX alpha), as its prosthetic group are known. The present work describes the isolation and structure elucidation of two further bile pigments, biliverdin IX delta and neobiliverdin IX delta. This is the first report of naturally occurring bile pigments with IX delta structure.

Sequence analysis of proteolytic fragments of 124-kilodalton phytochrome from etiolatedAvena sativa L.: Conclusions on the conformation of the native protein

Proteolytic fragments were obtained by limited proteolysis of 124-kDa (kilodalton) phytochrome from etiolatedAvena sativa using trypsin, endoproteinase-Lys-C, endoproteinase-Glu-C and subtilisin. The fragments were separated by sodium dodecyl sulfate gel electrophoresis, blotted onto activated glass-fiber sheets and investigated by amino-acid sequencing in a gas-phase sequencer. Determination of N-terminal sequences in three to six Edman degradation steps allowed the exact localization of the fragments within the published entire amino-acid sequence of 124-kDaAvena phytochrome (H.P. Hershey, R.F. Barker, K.B. Idler, J.L. Lissemore, P.H. Quail (1985), Nucleic Acids Res.13, 8543-8559). From the knowledge of the exact sites for preferred proteolytic cleavage of undenatured phytochrome, conclusions on the conformation of the phytochrome protein were drawn. Sites of preferred cleavage are considered to be freely exposed to the environment whereas potential cleavage sites which are resistant to proteolysis over a long time are considered to be localized in the interior of the native phytochrome. Two different sites which are exposed in the far-red-absorbing form but not in the red-absorbing form of phytochrome are localized at amino-acid residues 354 and 753, respectively. The N-terminal region which is exposed only in the red-absorbing form stretches only as far as amino-acid residue 60.

Phytochrome regulation of mRNA levels of ribulose-1,5-bisphosphate carboxylase in etiolated rye seedlings (Secale cereale)

The effect of red light and far-red light on the appearance of mRNA for the small and large subunit of ribulose-1,5-bisphosphate carboxylase in rye seedlings has been analysed. Irradiation of etiolated seedlings with a pulse of red light increased the mRNA level of the small subunit by a factor of 7-10 and that of the large subunit by a factor of 3. A pulse of far-red light resulted in a much lower, but measurable increase. The effect of red light is reverted by an immediate far-red pulse, demonstrating the classical phytochrome response.In vitro transcription experiments with nuclei isolated from red light-treated seedlings showed that the transcription rate of the small subunit mRNA was increased only by a factor of 1.5-2.5, indicating posttranscriptional as wells as transcriptional regulations of the small subunit of ribulose-1,5-bisphosphate carboxylase.