Transgenic approaches for cyanogen reduction in cassava

For cassava to become a safe and acceptable crop, it is necessary to reduce the cyanogen levels in cassava foods. While this objective can be achieved by processing procedures, recent findings have shown that it is also possible to achieve it by suppression of cyanogen synthesis or by accelerating cyanogen turnover and volatilization. In 2003, cyanogen-free cultivars were generated by selective inhibition CYP79D1/D2 gene expression. The CYP79D1/D2 enzymes catalyze the first-dedicated step in cyanogen synthesis. Tissue-specific inhibition of CYP79D1/D2 expression in leaves lead to a 99% reduction in root cyanogen levels, indicating that the cyanogenic glycoside, linamarin, is synthesized in leaves and transported to roots. An alternative strategy to the reduce cyanogen content is to enhance cyanogen detoxification and cyanide volatilization during processing. This strategy has the advantage that cyanogen levels in unprocessed roots are not altered, potentially providing protection against herbivory andlor theft. To produce cultivars that promote rapid cyanide volatilization, hydroxynitrile lyase (HNL), which catalyzes the last step in cyanogenesis, was overexpressed in roots. Elevated HNL activity resulted in a 3-fold increase in the rate of cyanogen turnover. Importantly, the cyanogen content of the transformed and wild-type plants was identical, a potential benefit for farmers.     

Primary structure of the alanine subunit of ricin T from seeds of the Central Asian castor oil plant. V. Peptides obtained by cyanogen bromide cleavage

The cleavage of the carboxymethylated Ala subunit of ricin T by cyanogen bromide has been performed. Four fragments have been isolated in the individual state by gel filtration and high-voltage paper electrophoresis. The sequence of the cyanogen bromide peptides in the protein chain has been established. Partial structures of three cyanogen bromide fragments have been determined.Institute of Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodynkh Soedinenii, No. 6, pp. 845–848, November–December, 1988.     

Condensed 1,3-benzothiazinones. 1. Facile synthesis of 2-amino-1,2,4-triazolo[5,1-b][1,3]-benzothiazin-9-one

Treating 2-mercaptobenzohydrazide ( 1a ) with cyanogen bromide gave 3-amino-2-imino-3,4-dihydro-2.H-1,3-benzothiazin-4-one ( 2a ). This compound underwent further cyclocondensation with a second molecule of cyanogen bromide or S-methylisothiourea sulfate to afford the biologically interesting 2-amino-1,2,4-triazolo-[5,1-b][1,3]benzothiazin-9-one ( 3c ). Compound 3c could also be prepared directly from 1a by treating with excess amount of cyanogen bromide in more satisfactory yield.     

Primary structure of the alanine subunit of ricin T from seeds of the Central Asian castor oil plant. V. Peptides obtained by cyanogen bromide cleavage

The cleavage of the carboxymethylated Ala subunit of ricin T by cyanogen bromide has been performed. Four fragments have been isolated in the individual state by gel filtration and high-voltage paper electrophoresis. The sequence of the cyanogen bromide peptides in the protein chain has been established. Partial structures of three cyanogen bromide fragments have been determined.     

Synthesis of 8-Halopurines by Reaction of Lithiated Purines with Appropriate Halogen Donors

Purines lithiated in the 8-position, can be trapped with hexachloroethane, dibromotetrachloroethane, cyanogen bromide and cyanogen iodide, to give a variety of 8-halopurines in excellent yields.     

吹扫捕集气相色谱法分析土壤中熏蒸剂氰与氰化氢残留量

采用吹扫捕集气相色谱法建立了土壤中熏蒸剂氰和氰化氢的分析方法,对土壤中氰和氰化氢预处理的吹扫温度、吹扫时间和吹扫载气(N2)流速进行了优化。最佳吹扫参数为:以10%H2SO4溶液作溶剂、吹扫温度80℃、吹扫时间60 min和吹扫载气(N2)流速40 mL.min-1。氰和氰化氢在0.2～10 mg.L-1质量浓度范围内线性关系良好,相关系数(r2)分别为0.999 1和0.998 3。在优化条件下,土壤中氰和氰化氢的平均回收率分别为95%和96%,相对标准偏差分别为3.6%和5.2%,检出限(S/N=3)分别为0.012、0.021 mg.kg-1,定量下限(S/N=10)分别为0.040、0.070 mg.kg-1。用100 mg.kg-1氰熏蒸土壤48 h,氰及其降解产物氰化氢在土壤中的残留量分别为0.32 mg.kg-1和5.68 mg.kg-1。该方法简便快速,精密度与准确度均符合要求,适用于土壤中氰和氰化氢残留量的检测。     

2-Trimethylsilylethyl sulfides in the von Braun cyanogen bromide reaction: selective preparation of thiocyanates and application to nucleoside chemistry

Mixed 2-(trimethylsilyl)ethyl sulfides were synthesized and used in the von Braun cyanogen bromide reaction for preparing selectively thiocyanates in high yield. We show here that this cleavage reaction is highly selective in methanol in comparison with the reaction of the corresponding non-silyl sulfide analogues. This reaction was applied to the synthesis of nucleosidic thiocyanates such as the new nucleosides 14 and 18 in the search for mechanism-based inhibitors of ribonucleoside diphosphate reductase and bioactive molecules. The selective cleavage is possible for sulfides bearing hydroxyl functions and aromatic rings. The reactions of cyanogen bromide as cyanating and brominating agent were observed for the first time under the same conditions with the naphthoxyhexyl 2-trimethylsilylethyl sulfide 7, which, treated with cyanogen bromide in dichloromethane, led selectively to the p-bromonaphthoxyhexyl thiocyanate 10 in 89% yield. Another reaction induced by cyanogen bromide was observed in dichloromethane with the 2-(trimethylsilylethyl)thio nucleoside 13, which gives the corresponding symmetrical disulfide 21 in good yield.     

Molecular Rydberg transitions. Intermediate coupling in simple bromides

An intermediate coupling analysis of the low-energy π → σ Rydberg transitions of hydrogen bromide, cyanogen bromide, acetylene bromide and alkyl bromides is presented. Exchange and spin-orbit coupling parameters are calculated and their variations discussed. The Br 5s orbital is delocalized in the larger alkyl bromides and Br 4p is heavily involved in π bonding in acetylene and cyanogen bromides.     

Neue verfahren zur jodometrischen mikrobestimmung von jodid- bzw. Bromidion

The methods described above are based on the fact, that iodide can be determined as iodate on iodometric way after oxidation with freshly prepared chlorine water and after removal of excess of free chlorine by means of potassium cyanide. However oxidation may be carried out by adding of hypobromite the excess of which can be removed by adding of phenol water.Bromide can be transformed to BrCl by means of an excess of chlorine water. BrCl reacts with potassium cyanide under formation of cyanogen bromide and chloride. The excess of free chlorine would be removed as cyanogen chlorine and chloride. The cyanogen bromide formed can be measured on the usual iodometric way.     

Condensed thiolane 1,1-dioxide system

Alkylation of trans-N-alkyl(or aryl)-N'-(3-hydroxy-1,1-dioxothiolan-4-yl) thioureas with ethyl p-toluenesulfonate, and the reaction of cyanogen bromide wiht an ethyl p-toluenesulfonate, and the reaction of cyanogen bromide with trans-3-hydroxy-4-aminothiolan-1,1-dioxides have given salts of trans-2-iminoperhydrothieno[3,4-d]-oxazole 5,5-dioxides. Rearrangement of these oxazolidines in the presence of bases afford perhydrothieno[3,4-d]imidazole-2-one 5,5-dioxides.Deceased.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 268–271, February, 1988.     

Nouvelle voie d'accès a la série de l'hexahydroazépino[4,5-b]indole. Réarrangement de l'hexahydroindolo-[2,3-a]quinolizine par action de BRCN

The action of cyanogen bromide on hexahydroindolo[2,3-a]quinolizines leads to hexahydroazepino[4,5-b] indoles through a novel rearrangement during which the cyanogen bromide probably reacts in two different ways with the species present.     

Primary structure of triacetinase — An esterase from cotton seeds IV. Peptides of the chymotryptic and thermolytic hydrolysis of cyanogen bromide fragments of triacetinase

Summary 1. Peptides from a chymotryptic hydrolyzate of cyanogen bromide fragment B-7 have been isolated and characterized. The structure of some peptides of the chymotryptic hydrolyzate have been studied and this has enabled the tryptic peptides to be linked up.2. The peptides of a thermolysin hydrolyzate of cyanogen bromide B-5 have been isolated and characterized. The study of the structure of the thermolysin peptides has permitted the linking of two tryptic peptides.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 248–253, March–April, 1978.     

New spot-test for cyanide ion and cyanogen gas

A new, rapid and simple spot test has been developed for detection of both cyanide ion and cyanogen gas. The cyanogen gas must first be converted into cyanide ion by reaction with sodium hydroxide. On addition of a Cu(II) solution the cyanocuprate(I) complex formed reduces the molybdate solution to molybdenum blue.     

Nondestructive Analysis of the Chemical Reactivity of Copper/Chromium/Silver Impregnated Charcoals

Abstract

A nondestructive analysis for chemical reactivity of commercial whetlerite (activated charcoal impregnated with copper, chromium and silver) is described. It is based on monitoring the disappearance of carbon monoxide in mixtures with air from known flows passing through the charcoal in a flow-through mode. Correlation of CO oxidation was found with measurements of cyanogen chloride retention using the same samples. the disappearance of carbon monoxide was also followed using a recycle procedure. However, the results using this particular method for CO oxidation may not lead to a good correlation with cyanogen chloride retention.     

Cyanogen Bromide Promoted Thiol Dimerization

The synthesis of alkyl thiocyanates by the reaction of thiols with cyanogen chloride has been known,¹ although it is generally supersede by the more convenient displacement of alkyl halides with alkali thio-cyanates.² We wish to describe the behavior of sodium thiolates toward cyanogen bromide.     

Comparison of the performance of immunosorbents prepared by site-directed or random coupling of monoclonal antibodies.

The majority of methods used to prepare immunosorbents immobilize antibodies through their reactive amino acid residues. The bound antibody activity of these immunosorbents is low. Hydrazide-based matrices couple antibodies through carbohydrate chains frequently located in the Fc region. This paper reports a comparative study of the performance of immunosorbents prepared by cyanogen bromide or hydrazide immobilization methods. The experiments utilized murine monoclonal antibodies to the human plasma proteins Factor IX or Protein C. The antibodies were immobilized at low densities to beaded agarose matrices which had similar properties. The hydrazide immunosorbents had binding efficiencies which were lower (anti-Factor IX) or up to 1.6-fold higher (anti-Protein C) than comparable cyanogen bromide coupled gels. However, there was no improvement in performance due to lower recoveries of bound protein from the hydrazide gels. Control experiments demonstrated that oxidation of antibody which is required for its coupling to hydrazide gels had no effect on antibody binding to antigen. Our results indicate that, as with cyanogen bromide coupling methods, site-directed immobilization through carbohydrate residues results in a restricted ability to bind to antigen. Both monoclonals were found to contain carbohydrate in their Fab' regions through which coupling may have occurred. The frequency of carbohydrate in the Fab region and the ability to control glycosylation at these sites are factors which may impact the utility of carbohydrate-directed immobilization of antibodies.     

p-Nitrophenylcyanate—An efficient,convenient, and Nonhazardous substitute for cyanogen bromide as an activating agent for sepharose

The reaction of aromatic cyanates with agarose-based resins was investigated. Phenylcyanate yielded aliphatic-aromatic imidocarbonates as the major product, whereasp-nitrophenylcyanate acted as a cyanylating agent, yielding mainly cyanate esters on the resin. Such cyanate esters were recently also shown to be the active group on cyanogen bromide-activated Sepharose; hence, the stable and nonvolatilep-nitrophenylcyanate was found to be a very convenient substitute for the highly hazardous cyanogen bromide. Activations withp-nitrophenylcyanate could be done safely outside a hood. Employing triethylamine instead of the commonly used inorganic bases, an optimized activation procedure was developed that is about 10 times more efficient than conventional cyanogen bromide activation. Since both cyanogen bromide andp-nitrophenylcyanate-activated resins contain cyanate esters as active groups, the coupling of ligands proceeded in an identical fashion in both cases.     

溴化氰裂解结合电喷雾串联质谱测定电泳分离蛋白的C端序列

C端测序是蛋白质及多肽一级结构确认的重要组成部分,也是重组蛋白药物质量控制的重要依据。建立了溴化氰裂解结合电喷雾串联质谱测定蛋白质C端序列的方法,并应用于重组人肿瘤坏死因子受体和纽兰格林的C端测序。首先根据待测蛋白序列进行溴化氰理论裂解,如果C-端肽段理论分子量在500~5000U之间,则将待测样品进行SDS-PAGE分离,考马斯亮兰染色,然后进行胶内溴化氰裂解,最后应用基质辅助激光解吸/电离飞行时间质谱(MALDI-TOF-MS)测定C-端肽段的分子量,电喷雾串联质谱对C端肽段进行测序。应用本方法分别测定了这两个蛋白质C端19个和11个氨基酸残基序列。研究结果表明:本方法灵敏、有效、实用性较强,可适用于部分重组蛋白药物的质量控制和蛋白质的结构确证,是对目前蛋白质C端测序方法的有效补充。     

A highly reduced cyanogen ligand derived from cyanide reductive coupling

The synthesis, structure, and spectroscopic features of a bimetallic cyanogen complex obtained from the reductive coupling of cyanide by a niobium(IV) precursor are described, and a mechanism for the coupling reaction is proposed based on DFT calculations.     

Synthesis of 5H-benzoxazolo[3,2-a]quinazolin-5-ones

5H-Benzoxazolo[3,2-a]quinazolin-5-ones (Xa-d) were synthesized in excellent yields from N-(2-hydroxyphenyl)anthranilic acids (Ia-d) and cyanogen bromide. The synthesis was based on the mechanistic consideration of the reactions of salicylic acid with cyanogen bromide previously reported in the literature. A versatile alternative route to these novel heterocyclic compounds was through thermal cyclization of N-(2-benzoxazolyl)-2-fluorobenzamides (XIII) obtained by reacting 2-fluorobenzoyl chloride with 2-aminobenzoxazoles. The reaction of Xb with ethanol in the presence of potassium hydroxide gave an ethoxyquinazolinone (XVII). Similarly, the alkaline hydrolysis of Xb afforded an quinazolindione (XVIII).