MODELS FOR THE CHROMOPHORE STRUCTURE OF THE PHOTOTRANSFORMATION INTERMEDIATES OF PEA PHYTOCHROME IN VITRO

Abstract— The changes in the chromophore structure of pea phytochrome during phototransformation in vitro from the red-light-absorbing form (P_r) to the far-red-light-absorbing form (P_fr), and from P_fr to P_r, were analysed in terms of wavelength and oscillator strength of absorption, using the zero-differential overlap approximation of the molecular orbital theory for electrons. The effect of a point-charge and a point-dipole on the optical absorption of phytochromobilin intermediates were examined using the stationary perturbation theory for degenerate states. The results indicate that the cis-trans photoisomerization of the pyrrole ring D, if any, occurred within 10 μs after a laser-flash excitation of the phytochrome, and that the conformations of phytochromobilin and the protein moiety of phytochrome were not significantly changed during the period of examination of phototransformation in either direction.     

EVENTS IN THE PHYTOCHROME MOLECULE AFTER IRRADIATION

The photoconversion of Pr to Pfr has been investigated by a large number of investigators. We have previously demonstrated that Z, E isomerization of the tetrapyrrole chromophore is involved in the photoconversion. It is the best candidate for the primary photoreaction. Conformation and configuration of the Pr chromophore will be compared with that of chromophores in phycocyanin. The crystal structure of phycocyanin had been elucidated by x-ray analysis. Proton transfer and/or Z, E isomerization of the tetrapyrrole are probably involved in different steps of the photoconversion in phytochrome and in photoreversible phycobiliproteins. Fluorescence decay kinetics of irradiated Pr and intermediate formation show heterogeneity. Possible reasons for this heterogeneity will be discussed.     

ORIENTATION OF RETINYLIDENE CHROMOPHORE OF HYPSORHODOPSIN IN FROG RETINA

Abstract— Hypsorhodopsin and bathorhodopsin were formed in the frog retina by irradiating rhodopsin at liquid He temperature (9 K) with orange light (> 520 nm) and blue light (437 nm), respectively. Hypsorhodopsin was converted to bathorhodopsin in the retina by warming above 32 K in the dark. Similar phenomena were observed in the rod outer segment suspension. A difference spectrum between hypsorhodopsin and bathorhodopsin in the retina produced by warming was almost identical with that in the rod outer segment suspension. This suggests that the transition dipole moment of hypsorhodopsin is parallel to the disk membrane plane which is also parallel to that of bathorhodopsin.     

三维球状液晶的模型分子（C6H5）Si（OC6H4）3N结构的PM3研究

三维球状液晶的模型分子（Ｃ６Ｈ５）Ｓｉ（ＯＣ６Ｈ４）３Ｎ结构的ＰＭ３研究＊丁涪江张良辅（中国科学院成都有机化学研究所成都６１００４１）关键词三苯并硅杂烷环状分子ＰＭ３方法液晶分子多为棒状一维结构和盘状二维结构。最近发现三维球状液晶分子，即长链烷烃取代...     

EFFECTS OF N-PHENYLIMIDE S-23142 AND N-METHYL MESOPORPHYRIN IX ON THE SYNTHESIS OF THE PHYTOCHROME CHROMOPHORE IN PEA EMBRYONIC AXES

Abstract Treatment of imbibed embryonic axes taken from seeds of Pisum sativum with N-phenylimide S-23142, a herbicide that has been suggested to inhibit protoporphyrin synthesis, or with N -methyl mesoporphyrin IX, an inhibitor of the iron chelatase for heme, resulted in a significant decrease in the amount of spectrophotometrically detectable phytochromc in the axes in both cases. However, the amount of immunochemically detectable phytochrome was not affected by either treatment. If S-23142 inhibits the synthesis of protoporphyrin IX in pea, it appears that the conversion of protoporphyrinogen IX to protoporphyrin IX is involved in the biosynthesis of the phytochrome chromophore. The conversion of protoporphyrin IX to heme (Fe-protoporpbyrin) also appears to be a step in the biosynthesis of the chromophore, since N -methyl mesoporphyrin IX prevented the synthesis of spectrophotometrically detectable phytochrome but did not affect the magnesium chelatase activity required for the synthesis of chlorophyll in pea embryonic axes. The results suggest that protoporphyrinogen IX, protoporphyrin IX and heme are intermediates in the biogenesis of the phytochromc chromophore. The pathway to phytochromobilin might become fixed after protoporphyrin IX, being directed toward the Fe branch for heme rather than to the Mg branch for chlorophyll.     

土槿甲酸的分子结构及晶体结构的研究

土槿甲酸是抗真菌土槿皮酸的成分之一.晶体属四方晶系,空间群P422晶胞参数a=b=8.956Å,c=51.834Å,α=β=γ=90°,z=∑a_n=4564.土槿甲酸的粗结构模型和化学结构式通过直接法测定.     

THE IMPORTANCE OF THE MICROENVIRONMENT SURROUNDING A CHROMOPHORE IN DETERMINING ITS SPECTROSCOPIC BEHAVIOR*

Se pone especial énfasis en la importancia del microambiente de un grupo como factor determinante del comportamiento fotoquímico, emisión y dicroismo circular de móleculas biológicas. Los ejemplos dados incluyen la fotoquímica de la ribonucleasa, la dependencia de las propiedades luminiscentes de amino acidos aromáticos con la temperatura, y el comportamiento espectroscópico de los dinucleótidos.     

鹤草酚的晶体结构和分子结构

鹤草酚晶体属三斜晶系,空间群为PI,晶胞参数为a=9.901(3),b=11.195(4),c=11.752(4)Å,α=80.74(3),α=75.66(3),γ=76.46(3)°,晶胞内分子数Z=2.用SyntexP3/R3型四圆衍射仪收集到2891个独立衍射强度.以直接法SHELXTL解出晶体结构.结构参数的修正采用了块对角矩阵最小二乘法,最后得偏离因子R=5.7%.晶胞中含有d-,l-两种对映体分子,它们彼此以I连系组成外消旋体.每分子中的两个六环分别同相邻的氧共面,其双面角为14.2°.两个六环通过碳(sp³)桥相连,并由于形成分子内氢键O-H…O(分别为2.705Å和2.745Å)而限制了自由转动.     

晶区分子链构象及拉伸取向对聚酰胺-6分子运动的影响

用声频共振法在-150°—170℃范围内测定了晶区构象为α、γ、γ+α型以及经不同拉体程度的聚酰胺-6单纤维的动态力学性质的温度谱。除三个已知的内耗峯—— -110℃(β_a),-40℃(β’_a),50℃(α_a)以外,对晶区为γ构象且含有单体及低聚体的聚酰胶-6观察到一个新的内耗峯,130℃(α’_a)。具有α构象的试样,其α_a内耗峯出现的温度较具有γ构象的试样为高。 经碘处理而未脱碘的聚酰胺-6,(β’_a)内耗峯高度显著增加,进一步证实β’_a内耗峯与自由酰胺基的运动有关。β’_a内耗峯的高度亦随拉伸比的增加而增高,说明在拉伸过程中,酰胺基之间的氢键有破坏的可能性。 出现在130℃处的α’_c内耗峯随拉伸比的增加其高度显著地下降,当拉伸到3.8倍时不再出现α’_c内耗峯。结合晶区分子链构象及碘处理对α’_c内耗峯的影响,我们认力α’_c内耗峯应为γ构象部分的松弛运动。     

THE CRYSTAL AND MOLECULAR STRUCTURE OF TRIPTONIDE

<正> Triptonide, C20H22O6, was extracted from tripterygium wilfordii Hook F. of Fujian province and its structure was determined by X-ray crystallo-graphic analysis, Mr = 358. 39, monoclinic, P21,a = 11. 144(5), 6 = 6. 467(2), c= 12. 681(6)(?), β=103.54(4)°, V= 888. 4(?)3. Z = 2, F(000) = 380, Dc= 1. 34g/ cm3. The structure was solved by direct methods and refined by full matrix least-squares method to a final R value of 0. 042 for 1934 reflections with I> 3σ(I). Crystals of triptonide are isostructural with those of triptolide.     

硬弹性聚丙烯晶相和非晶相分子链取向的研究

本文用力学-振动光谱研究了硬弹性聚丙烯(HEPP)晶区和非晶区分子链在拉伸时取向的变化.我们发现在红外光谱中,1130—1190cm~(-1)波数范围内存在着三个峰,其中1167cm~(-1)处的峰是与结晶相长螺旋分子链相关的构象谱带,其谱带的强弱变化是与998cm~(-1)结晶谱带在拉伸时的变化趋势一致的.1159cm~(-1)谱带能够被归属于无定形谱带.而1152cm~(-1)处的峰也许是与短螺旋分子链构象谱带相关的.我们用计算机的二次微分、解卷积以及分峰程序测定了拉伸时HEPP晶区和非晶区分子链的取向函数,结果发现HEPP无定形分子链取向随拉伸比增加而增加,而晶区分子链的取向随拉伸比的增加先下降,直至拉伸比为1.5(第二次屈服点)后才逐渐增加.     

从中药佛手中分离鉴定两个柠檬油素二聚体

用 IR、NMR和X-射线晶体衍射分析了从佛手中分离出来的两个柠檬油素二聚体,证明它们的化学结构分别是顺式头-尾-3,3′,4,4′-柠檬油素二聚体(1)和顺式头-头-3,3′,4,4′-柠檬油素二聚体(2)。通过光反应从柠檬油素制备了1和反式头-头-3,3′,4,4′-柠檬油素二聚体(3)。     

EVIDENCE FOR THE EXISTENCE OF MEMBRANE-ASSOCIATED PHYTOCHROME IN THE CELL

Abstract Comparative fluorescence and photochemical studies of phytochrome in etiolated seedlings of maize and in soluble and membrane-containing fractions isolated from them were camed out. The membrane fractions prepared in the absence of Mg²⁺ from etiolated coleoptiles contained 13% of total photoreversible phytochrome, which was readily solubilized by mild detergents. Its molecular size was indistinguishable from soluble phytochrome and equal to nondegraded maize phytochrome. Low-temperature fluorescence studies with intact tissue found that the position of the emission maximum at 85 K (λ_max) and the extent of the phototransformation of the red-absorbing form (Pr) into the first stable photoproduct, lumi-R, at 85 K (γ₁), varied in different parts of etiolated seedlings: λ_max and γ₁ reached their maximum values in the tips of coleoptiles and roots, 686 nm and 0.30–0.40, whereas the lowest values, 682 nm and ca 0.05, were observed in the root base. These parameters correlated well with those obtained for the pigment in the soluble and membrane-containing fractions: 684 and 680 nm, and 0.33 and 0.06, respectively. The extent of the Pr phototransformation into the far red-absorbing form (Pfr) (γ₂) did not differ much: values of 0.80–0.85 and 0.70–0.75 correlated with the high and low values of γ₁. These variations of the parameters were interpreted in agreement with our previous observations in terms of two phytochrome A species whose relative concentrations vary depending on the experimental conditions—the longer wavelength bulk light-labile species with high γ₁ (Pr″), and the shorter wavelength minor light-stable species with low γ₁ (Pr″). Close similarity between Pr’and the soluble phytochrome and between Pr″ and the membrane-bound phytochrome points to the possible origin of the native Pr’and PrPrime; species, thus providing evidence for the existence of membrane-bound pigment in the cell.     

INTRACELLULAR DICHROIC ORIENTATION OF THE BLUE LIGHT-ABSORBING PIGMENT AND THE BLUE-ABSORPTION BAND OF THE RED-ABSORBING FORM OF PHYTOCHROME RESPONSIBLE FOR PHOTOTROPISM OF THE FERN Adiantum PROTONEMATA

The intracellular localization and orientation of the receptors for the blue light-induced phototropism in the fern Adianrum protonemata, phytochrome and the blue light-absorbing pigment, were investigated by combining the techniques of cell centrifugation and of microbeam irradiation with linearly polarized light. The phototropic response was induced in the cells even after they had been centrifuged basipetally to spin down the endoplasm from the apical region. When a polarized blue microbeam was given to a flank of the apical region of the protonema, the phototropic response after compensation of phytochrome effect by far-red light was most effectively induced when the polarization plane was parallel to the long axis of the cell. If protonemata were pre-irradiated with blue and far-red light, the phototropic response was mediated through phytochrome alone. If such pre-irradiated protonemata were similarly irradiated with a polarized blue microbeam, polarized light vibrating parallel to the cell axis was again most effective in inducing the response. These results indicate that both the blue light-absorbing pigment and the phytochrome responsible for the blue light-induced phototropism in Adiantum are confined to the plasma membrane and/or the ectoplasm and that the transition moments of their blue-absorption bands are nearly parallel to the cell surface.     

秃毛冬青甲素分子结构及晶体结构的测定

秃毛冬青甲素为一种新木脂类化合物,在氯仿中重结晶得无色透明的六边形晶体,它的分子式为C₁₄H₁₆O₆,分子量280.09,计算密度1.443g/cm³,m.p.195～197℃.