- An unexpected vestigial protein complex reveals the evolutionary origins of an s-triazine catabolic enzyme
-
Cyanuric acid is a metabolic intermediate of s-triazines, such as atrazine (a common herbicide) and melamine (used in resins and plastics). Cyanuric acid is mineralized to ammonia and carbon dioxide by the soil bacterium Pseudomonas sp. strain ADP via three hydrolytic enzymes (AtzD, AtzE, and AtzF). Here, we report the purification and biochemical and structural characterization of AtzE. Contrary to previous reports, we found that AtzE is not a biuret amidohydrolase, but instead it catalyzes the hydrolytic deamination of 1-carboxybiuret. X-ray crystal structures of apo AtzE and AtzE bound with the suicide inhibitor phenyl phosphorodiamidate revealed that the AtzE enzyme complex consists of two independent molecules in the asymmetric unit. We also show that AtzE forms an 22 heterotetramer with a previously unidentified 68-amino acid-long protein (AtzG) encoded in the cyanuric acid mineralization operon from Pseudomonas sp. strain ADP. Moreover, we observed that AtzG is essential for the production of soluble, active AtzE and that this obligate interaction is a vestige of their shared evolutionary origin. We propose that AtzEG was likely recruited into the cyanuric acid–mineralizing pathway from an ancestral glutamine transamidosome that required protein–protein interactions to enforce the exclusion of solvent from the transamidation reaction.
- Esquirol, Lygie,Peat, Thomas S.,Wilding, Matthew,Liu, Jian-Wei,French, Nigel G.,Hartley, Carol J.,Onagi, Hideki,Nebl, Thomas,Easton, Christopher J.,Newman, Janet,Scott, Colin
-
-
Read Online
- Metal-mediated reactions towards the synthesis of a novel deaminolysed bisurea, dicarbamolyamine
-
A new selective cobalt acetate tetrahydrate or cerium nitrate hexahydrate mediated cleavage of the C-N bond of a benzoyl isothiocyanate derivative to give (carbamoylamino)methanethioamide is presented. The cleavage of the C-N could not be achieved in the absence of thione. The novel silver-mediated conversion of a thione to the carbonyl was achieved on 1-((benzamido)formyl)urea and replicated on (carbamoylamino)methanethioamide to give the deaminolyzed bisurea (dicarbamolyamine). The compounds were characterized by IR, NMR, microanalysis and GC-MS. The single crystal X-ray diffraction studies of the crystal structures of compounds I, II, III and V is discussed.
- Odame, Felix,Hosten, Eric,Tshentu, Zenixole R.
-
-
Read Online
- ACID-CATALYSED HYDROLYSIS OF CYANAMIDES: ESTIMATES OF CARBODI-IMIDE BASICITY AND TAUTOMERIC EQUILIBRIUM CONSTANT BETWEEN CARBODI-IMIDE AND CYANAMIDE
-
N-cyanourea is demonstrated as an intermediate in the hydrolysis of dicyanamide which is shown to react as its carbodi-imide tautomer.The hydrolysis of N-cyanourea, dicyanamide, and NN'-dimethylcyanoguanidine is specific acid-catalysed.Generaln acid catalysis is demonstrated for ht e hydrolysis of NN'-dimethylcyanoguanidine and is considered to be specific acid-nucleophilic.Assuming the carbodi-imide mechanism also holds for hte specific acid catalysed hydrolysis of cyanamide the tautomeric equilibrium constant for formation of ht eparent carbodi-imide in water at 25 deg C is estimated to be have a value within one unit of zero.Rate constant are reported for alkaline hydrolysis of cyanamides.
- Hill, Stephen V.,Williams, Andrew,Longridge, Jethro L.
-
-
Read Online
- A urea process for preparing diphenyl urea cleaning process
-
The invention discloses a clean process for preparing diphenyl urea by a urea method, and belongs to the technical field of diphenyl urea preparation. The clean process comprises the following steps: under the protection of an inert gas, adding an excessive amount of aniline into a reactor, heating to a first-stage reaction temperature, and keeping a certain inert gas flow; continuously adding urea into the reactor within a certain time through a continuous feeding hopper; heating to a second-stage reaction temperature and reacting to prepare the diphenyl urea. In the process, the aniline in the reactor is heated to a reaction temperature, and then the urea is added, so that the urea can be pyrolyzed quickly at a high temperature immediately to generate isocyanate, a byproduct of biuret is reduced, the yield of diphenyl urea is increased, meanwhile, the urea is continuously added into the reactor through the continuous feeding hopper, the production of the isocyanate can be controlled, the contact probability between isocyanate molecules and the aniline is increased, the contact probability between the isocyanate molecules and the urea is reduced, the byproduct of biuret can be reduced, and the yield of the diphenyl urea is increased.
- -
-
Paragraph 0029; 0030; 0031
(2017/03/14)
-
- PROCESS FOR STRAIGHTENING KERATIN FIBRES WITH A HEATING MEANS AND DENATURING AGENTS
-
The invention relates to a process for straightening keratin fibres, comprising: (i) a step in which a straightening composition containing at least two denaturing agents is applied to the keratin fibres, (ii) a step in which the temperature of the keratin fibres is raised, using a heating means, to a temperature of between 110 and 250° C.
- -
-
-
- Methods And Devices For Preparing Biuret And Cyanuric Acid
-
Provided are methods and devices for preparing biuret and cyanuric acid by thermal decomposition of urea. Specifically, a product of thermal decomposition is cooled to precipitate a crystal and the precipitated crystal is dissolved using an alkali aqueous solution and cooled to obtain biuret having high purity. Furthermore, the cyanuric acid that is one of byproducts by the thermal decomposition of urea is effectively recovered with high purity.
- -
-
Page/Page column 5
(2008/06/13)
-
- Method and apparatus for preparing hydrazo-dicarbonamide using urea as starting material
-
The present invention relates to a method and apparatus for preparing hydrazodicarbonamide using urea as starting material economically and environmentally desirably. The apparatus includes a pyrolysis furnace to obtain biuret and ammonia by pyrolyzing urea; a recrystallization reactor to purify the biuret obtained from the pyrolysis furnace; a first reactor to obtain an metal monohalobiuret salt by reacting the biuret with metal hypohalogen compound or with halogen and base; a second reactor to synthesize the hydrazodicarbonamide by reacting the monohalobiuret metal salt with ammonia; and an ammonia evaporator to separate the excess ammonia from hydrazodicarbonamide and to supply the separated ammonia to an ammonia concentrator.
- -
-
-
- Urea synthesis process and apparatus
-
Urea is prepared by reacting ammonia and carbon dioxide in an apparatus comprising a vertical condensation and synthesis column (1) and a stripper (21), to provide a urea synthesis solution comprising urea, unreacted ammonia, unreacted carbon dioxide and water. The urea synthesis solution is transferred from the top of the vertical condensation and synthesis column (1) to the top of a stripper (21). Carbon dioxide is introduced into the bottom of the stripper (21) and contacted with the urea synthesis solution, thereby separating the unreacted ammonia and the unreacted carbon dioxide from the urea, and providing a mixed gas comprising ammonia, carbon dioxide and water. The mixed gas is transferred into the bottom of the vertical condensation and synthesis column (1), where it is reacted with liquid ammonia injected into the bottom and a middle of the vertical condensation and synthesis column (1). The mixed gas and liquid ammonia are condensed and react to form urea. Uncondensed gases are absorbed in an absorbing medium, which is subsequently recycled to the bottom of the vertical condensation and synthesis column (1).
- -
-
-
- Synthetic test soil
-
PCT No. PCT/EP97/00337 Sec. 371 Date Jul. 24, 1998 Sec. 102(e) Date Jul. 24, 1998 PCT Filed Jan. 24, 1997 PCT Pub. No. WO97/27482 PCT Pub. Date Jul. 31, 1997The present invention provides methods and compositions relating to synthetic test stains comprising isolated fibrin and/or fibrin precursors and blood plasma proteins. Kits for the preparation of synthetic test stains containing an isolated fibrin precursor and an initiator for converting the fibrin precursor to fibrin are also provided. In addition, methods for checking the efficiency of cleaning processes, and kits for carrying out these methods are provided.
- -
-
-
- Substituted 1,3,5-triazinetriones, for use against parasitic protozoa
-
Protecting against parasitic protozoa with substituted 1,3,5-triazinetriones of the formula STR1 in which R1 represents aromatic or heteroaromatic radicals, each of which is optionally substituted, R2 represents H, alkyl, alkenyl, alkinyl or aralkyl, each of which is optionally substituted, R3 represents one or more identical or different radicals from the group consisting of hydrogen, halogen, alkyl, halogenoalkyl, alkoxy, alkylthio, halogenoalkoxy, halogenoalkylthio, cyano, alkoxycarbonyl, alkylsulphonyl and halogenoalkylsulphonyl, R4 represents hydrogen, a straight-chain, branched or cyclic alkyl radical, alkenyl, alkinyl, aralkyl or aryl, each of which is optionally substituted, and R5 represents hydrogen, optionally substituted alkyl, alkenyl, alkinyl or aralkyl. Also novel intermediates therefor.
- -
-
-
- Process for the production of polyisocyanates with biuret structures
-
Polyisocyanates with biuret structures are produced at temperatures above 250° C. More specifically, an excess of a diisocyanate having aliphatically and/or cycloaliphatically bound isocyanate groups is reacted with a diamine containing aliphatically and/or cycloaliphatically bound amino groups at temperatures above 250° C. for relatively brief periods of time. Water and/or polyvalent alcohols may optionally be included in the reaction mixture. The polyisocyanates with biuret structures produced by this process are characterized by good color, good dilutability with covalent solvents and comparatively low viscosity.
- -
-
-
- 1-Aryl-4-hydrazinyl-s-triazin-2-ones
-
STR1 This invention relates to 1-aryl-4-hydrazinyl-1,2-dihydro-1,3,5-triazin-2-ones and 2-thiones of Formula I, processes for their preparation, isobiuret and 4-alkoxy-s-triazinone preparative intermediates, and methods of treating physiological disorders in humans and animals, in particular, cardiovascular disorders, including hypertension.
- -
-
-
- 6-Aryl-4-hydrazinyl-s-triazin-2-ones
-
STR1 This invention relates to 6-aryl-4-hydrazinyl-1,2-dihydro-1,3,5-triazin-2-ones and 2-thiones of Formula I, processes for their preparation, intermediates useful in said processes and methods of treating physiological disorders in humans and animals, in particular, cardiovascular disorders, including hypertension.
- -
-
-
- Blocked polyisocyanates formed from a polyisocyanate containing biuret groups and from an acetoacetic acid alkyl ester
-
The invention relates to polyisocyanates which are blocked with an acetoacetic acid alkyl ester.
- -
-
-
- Process for the preparation of polyisocyanates containing biuret groups
-
This invention relates to an improved process for the preparation of polyisocyanate mixtures containing biuret groups by the reaction of organic diisocyanates with compounds which react with isocyanate groups to form biuret groups, to the polyisocyanate mixtures obtained by this process and to the use thereof for the preparation of polyurethane resins by the isocyanate polyaddition process.
- -
-
-