Properties Of Serine Research Articles

Synthesis and Properties of Serine- and Threonine-Based Helical Polyacetylenes

Serine- and threonine-based acetylene monomers carrying hydroxyl group, N-tert-butoxycarbonyl-l-serine N‘-propargylamide (1), N-tert-butoxycarbonyl-l-threoine N‘-propargylamide (2), and their O-silylated monomers, N-tert-butoxycarbonyl-O-triethylsilyl-l-serine N‘-propargylamide (3) and N-tert-butoxycarbonyl-O-triethylsilyl-l-threonine N‘-propargylamide (4), were polymerized with a rhodium zwitterion catalyst in THF, MeOH, CH2Cl2, and toluene to afford the corresponding optically active poly(N-propargylamides) with moderate number-average molecular weights (4200−12 800) in good yields. The polymers exhibited large specific rotations (−172° to −955°) and clear CD signals at the absorption region of polyacetylene main chains. The CD signals of poly(1) and poly(2) appeared around 270−350 nm, while those of poly(3) and poly(4) appeared around 400 nm. It is considered that these polymers take helical structures with predominantly one-handed screw sense, whose helical pitches are different. The presence of intra...

Volumetric Properties of Serine in Glucose-water and Sucrose-water Mixed Solvents at 298.15 K

利用精密数字密度计测定了甘氨酸与不同组成的葡萄糖-水、蔗糖-水混合溶剂构成的三元系溶液的密度,计算了甘氨酸的表观摩尔体积、极限偏摩尔体积和理论水化数,根据结构水合作用模型讨论了迁移偏摩尔体积的变化规律,并与乙二醇-水和丙三醇-水等多羟基体系作了比较.结果表明,甘氨酸分子在多羟基化合物-水体系中增体积效应的大小与多羟基化合物所含OH基数目的多少有关.

Proteolytic activity in the maize pollen wall

A new protease from maize (Zea mays L.) pollen is described. It was purified using gel filtration, ion exchange and high performance liquid chromatography. SDS‐PAGE and HPLC showed that the enzyme has a dimeric structure of M, ca 60,000. Inhibitor investigations indicated an aspartic acid residue in its active site. The optimum pH for maize pollen aspartic proteinase activity was 5.6, and the optimum temperature was 45°C. The enzyme is easily eluted from the pollen grains and, as confirmed by enzymoblotting after isoelectric focusing, it is located in the pollen wall. Similar to metallo‐proteinases, its activity is inhibited by Zn2+. The pL value for purified aspartic proteinase, as estimated after IEF, was 5.0. Two‐dimensional electrophoresis analysis of proteins eluted from maize pistils suggests that the enzyme digests the proteins and may be involved in pollen‐tube germination. The properties of serine and aspartic proteinases from maize pollen are compared.

Glyoxylate aminotranferases from wheat leaves.

Chromatographic studies were made of the following aminotransferases in crude, dialyzed extracts of wheat leaves (Triticum aestivum L. var. Selkirk): alanine: glyoxylate; aspartate: glyoxylate; glycine: 2-oxoglutarate (EC2.6.1.4); serine: glyoxylate; L-aspartate: 2-oxoglutarate (EC 2.6.1.1); L-alanine: 2-oxoglutarate (EC 2.6.1.2).After partial purification, the properties of serine: glyoxylate aminotransferase were studied in greater detail. This reaction proceeded in the forward direction to no more than one-half completion but no reverse reaction could be detected. The enzyme showed optimum activity at pH 8.2, and Km values of 9.0 × 10−4 M for serine and 2.5 × 10−4 M for glyoxylate were obtained. No clear requirement for the coenzyme pyridoxal phosphate or for metal ion participation could be shown but orthophosphate activated the enzyme when the latter was isolated in either Tris buffer or distilled water. Various aspects of glycine metabolism are discussed in relation to this and other work recently reported using wheat blades.

Societies and Academies

PARIS. Academy of Sciences, August 9.—M. Henri Deslandres in the chair.—A. Blondel: A new optical or electrical apparatus for the measurement of oscillations of velocity and angular deviations. The method is based on the registration on a photographic film moving at a uniform rate of the angular displacements of a disc carrying a series of equidistant slits, the disc being attached to the axis of the machine under examination. An application of the method to the study of an internal-combustion engine is given.—M. Petot: Extract from a letter to M. Appell concerning the spherical representation of surfaces.—B. Deiaunay: The number of representations of a number by a binary cubic form with negative discriminant.—F. Carlson: The zeroes of the series of Dirichlet.—C. Fremont: Cause of the frequency ol breakages of rails at their extremities.—J. Rey; Perrot's experiment relating to the movement of rotation of the earth. In 1859 Perrot observed certain rotations in a jet of water flowing from a hole in the base of a cylindrical vessel, and regarded these as due to the rotation of the earth. Laroque, in 1860, concluded that the observed phenomena were not connected with the earth's rotation, but many phenomena in geophysics have since then been explained on the assumption of the validity of Perrot's views Experiments are described which lead to the conclusion that Perrot's views are erroneous, and fully confirm Laroque's criticisms.—H. Godard: Observations of the periodic comet Tempel II. made at the Bordeaux Observatory with the 38-cm. equatorial. The apparent positions of the comet and comparison stars for July 24, 25, and 27 are given.—A. Buhl; The symmetries of the electromagnetic and gravific field.—E. Darmois: The influence of ammonium molybdate on the rotary power of malic acid. A crystallised compound of malic acid and ammonium molybdate has been isolated. Its rotatory power is very high (+ 219°), and constant over a wide range of concentrations. There is a probability that this is not the only complex compound formed when ammonium molybdate is added to solutions of malic acid.—A. Portevin: The similitudes of micrographic aspect existing in various states between the iron-carbon (steels), copper-tin (tin bronzes), copper-zinc (brasses), and copper-aluminium alloys (aluminium-bronzes).—J. Bougault and P. Robin: Catalytic oxidation by unsaturated bodies (oils, hydrocarbons, etc.). Dichloroethyl sulphide, which alone or in solutiori is unaffected by oxygen, in presence of turpentine readily oxidises on exposure to air, the sulphoxide SO(CH2.CH2Cl)2 being formed. By a similar oxidation, thiodiglycol in presence of citral is readily oxidised by air to the sulphoxide SO(CH2.CH2.OH)2. —R. Souèges: The embryogeny of the Compositæ. The last stages of the development of the embryo in Senecio vulgaris.—P. Lesage: Experiments utilis-able in plant physiology on osmosis and on the aspiration due to evaporation.—M. and Mme. G. Villedteu: The action of rain on the deposits of copper mixtures on plants.—J. Amar: How to determine the output of workmen.—A. Migot: The formation of the axial skeleton in Eunicella (Gorgonia) Camolinii.—MM. Fauré-Fremiet, J. Dragoiu, and Mile. Du Vivier de Streel: The histochemical differentiation of the fœtal pulmonarv epithelium in the sheep.—M. Piettre and A. Vila.: Some properties of serine.—C. Lebailly: The virulence of the milk in apthous fever. The milk is virulent before any appearance of symptoms characteristic of the disease, the high temperature being the only indication of departure from the normal healthy condition.—E. Alilaire and E. Fernbach: Some observations on the culture of the tubercle bacillus in non-glycerinated media.