beta-Glucosidase of Penicillium funiculosum. II. Properties and mycelial binding

The properties of two isozymes of beta-glucosidase of Penicillium funiculosum (part I of this series) are described. The molecular weights of isozyme 1 was 2.3 x 10(5) by gel filtration and 1.2 x 10(5) by SDS gel electrophoresis, indicating two subunits. The molecular weight of isozyme 2 was unusually low for a fungal beta-glucosidase: 1.6 x 10(4) by gel filtration and 3.7 x 10(4) in the presence of isopropanol. The two enzymes differed from other fungal beta-glucosidases in their substrate specificities. They showed high activity with pNPG, cellobiose, cellotriose, cellotetraose, cellopentaose, gentiobiose, and laminarin, but were inactive with filter paper, CM cellulose, or derivatives or stabilized by bovine serum albumin and several alcohols such as butanol and propanol. It was inhibited by glucono-delta-lactone (K(i) = 0.67muM) and glucose (K(i) = 0.92mM).The enzyme was quantitatively adsorbed by P. funiculosum mycelium at pH 4 and the immobilized enzyme was as enzymically active as the free enzyme, but more heat stable. The binding efficiency was very high (5000 IU enzyme/g mycelium). It could be quantitatively eluted with buffers at pH 7 or by 0.02M Ca, Mg, or Al chlorides. The binding was selective, since mycelium grown on lactose could produce and also bind only beta-glucosidase isozyme 1, whereas mycelium grown on cellulose could produce as well as bind both beta-glucosidase isozymes as well as cellulases. Mycelial binding was unaffected by washing with EDTA or trypsinization, but was totally lost by washing with dilute KOH, HCl, or ethylenediamine.     

Interaction of wheat germ ca-dependent protein kinases with calmodulin antagonists and polyamines

The two soluble Ca²⁺-dependent protein kinases resolved from wheat (Triticum aestivum) embryo (protein kinases I and II) are inhibited by the phenothiazine-derived calmodulin antagonists trifluoperazine fluphenazine, and chlorpromazine. Protein kinases I and II are also inhibited by a variety of other calmodulin antagonists (including calmidazolium, amitriptyline, and iprindole), phosphodiesterase inhibitors (including flufenamic acid and papavarine) and by lanthanides. A number of compounds that inhibit mammalian Ca²⁺ - and phospholipid-activated protein kinase (protein kinase C) including quercetin, polymixin B sulfate, and polyamines (as well as phenothiazine derivatives) also inhibit protein kinases I and II. Poly-l-lysine and poly-l-ornithine activate both plant Ca²⁺-dependent protein kinases.     

Photocontrol of Hypocotyl Elongation in Light-Grown Cucumis sativus L. : Responses to Phytochrome Photostationary State and Fluence Rate

The effects of the calculated photostationary state of phytochrome (_c) and the photon fluence rate on the elongation growth of the hypocotyl of light-grown seedlings of Cucumis sativus L. are examined. Two threshold responses to _c are found at values of 0.06 and 0.43. At _c = 0.06, there is no response at any fluence rate. In the _c range 0.1 to 0.43, elongation growth does not respond to changes in _c. Above the second threshold (_c = 0.43), there is a strong response to changes in _c. At all values of _c at and above 0.1, there is a response to fluence rate. A linear relationship can be demonstrated between a factor comprised of the logarithm of phytochrome cycling rate (a fluence-rate-dependent process) and _c, and the growth response.     

Vitellogenin hormonal control in the green frog, Rana esculenta. Interplay between estradiol and pituitary hormones

1. The effect of estradiol and pituitary hormones on the titre of serum vitellogenin has been studied in Rana esculenta by rocket immunoelectrophoresis. 2. Hepatic synthesis of vitellogenin depends on physiological doses of estradiol. 3. Gonadotrophins enhance the uptake, presumably by acting directly on the oocyte plasma membrane. 4. In addition, our data support direct pituitary intervention on liver synthesis and/or release of vitellogenin. 5. Hormonal response, as evaluated by vitellogenin serum titres, tends to increase from November to July. This could be the expression of a modification, throughout the sexual cycle, of liver sensitivity to the hormones.     

南方菜豆花叶病毒外壳蛋白基因序列的分析

用重组DNA技术及序列分析法测定了南方菜豆花叶病毒RNA基因组3′端1,000个碱基的序列,以及由此序列推导出的整个外壳蛋白的氨基酸顺序,它与巳报导的基本上一致。介绍了用DNA的寡核苷酸水解混合物作为起始引物,以3′端不含PolyA尾巴且不能加上PolyA的病毒RNA作为模板合成互补DNA,及进一步无性繁殖此cDNA的方法。     

A kinetic model for the hydrolysis and synthesis of maltose, isomaltose, and maltotriose by glucoamylase

Kinetic results on the glucomylase-catalysed hydrolysis of maltose and maltotriose, and glucose polymerization into maltose and isomaltose up to 450 g/L total sugar concentration are presented. Whereas the enzyme has a faster hydrolytic and synthetic activity on alpha-(1-->4) than on alpha-(1-->6) linkages, at equilibrium, on the contrary, the isomaltose level which represents 15% (w/w) of the total sugar concentration at the highest investigated concentrations is much higher than the corresponding maltose level. Under a wide range of initial conditions, experimental results are adequately described by a new kinetic model with simple first- and second-order, or Michaelian-type, rate expressions for the reversible hydrolysis of maltotriose, maltose, and isomaltose. The model also accounts for the inhibition of hydrolysis by glucose, but does not consider the concentration of water which, under the present conditions, was not found kinetically limiting.     

水份含量对紫膜薄层某些光学性质的影响

本文研究在乾燥紫膜薄层中不同水合程度对光循环中间体M衰减速率,对园二色谱(CD)和蛋白紫外荧光光谱的影响.在相对湿度小于70%时,M衰减速率相对稳定,不随湿度改变而变化;但当湿度大于70%时,则衰减速率急剧上升.从可见区的CD光谱中,也发现了在相对湿度大于70%后,旋转强度急剧上升.蛋白紫外荧光光谱随湿度增加未发现有明显变化.实验结果说明一定水份的含量对紫膜完成质子泵功能是必不可少的,它能改变色素团的微环境,从而改变色素团和蛋白间的相互作用.     

有取向紫膜薄层光电位及其与光强度的关系

本文报道利用电泳法得到有取向紫膜薄层,并测定了在连续光照下由此薄层所产生的光电位.研究了相对湿度对光电位的影响.文中还从光电位和M产物对光强度的依赖关系,研究了二者间的相关关系.一些事实说明在M衰减的数个组分中,并不是每一组分都与光电位相关的.在M衰减过程中,可能存在有电荷沿膜平面的运动,它对M产物是有贡献的,但对膜电位却无贡献.     

Endodermal secretion of chitin in the 'cuticle' of the earthworm gizzard

The gizzard of earthworms is definitely of endodermal origin. Contrary to the opinion that tissue of endodermal origin is unable to synthesize chitin, the gizzard epithelium secretes large amounts of chitin-containing material which has special properties. 28.7 +/- 5.7% of the dry weight proved to be chitin; the microfibres form a random felt-like texture. They are not arranged in layers comparable to those found in arthropod cuticle. The protein content amounts to 44.9 +/- 7.1% of the dry weight; the remaining material contains at least uronic acids. In the protein matrix large amounts of the enzymes amylase and protease have been demonstrated. As the so-called cuticle is sloughed off at the lumen side, these enzymes are mingled with the gut contents. It might be called a gastric shield, as it closely resembles this structure, widespread among Mollusca. The thickness of the gizzard cuticle varies between 10 and 90 mum in Lumbricus terrestris and 10-50 mum in L. rubellus. Autoradiography has shown that it is replaced at a high rate. In Lumbricus terrestris it is renewed completely in less than 60 hr, and in smaller Lumbricus rubellus, this takes place in about 48 hr. These results are in agreement with the biochemical findings.