摘要:

AbstractCertain critical observations can be made with regard to the preparation and properties of artificially halogenated proteins on the basis of the study of the iodination and biosynthesis of thyroglobulin in the thyroid gland and its physico‐chemical properties. It appears that iodination causes two types of changes. The first has to do with halogenation method used. The damage is caused by the actual iodination conditions and can be avoided if the chemical iodination methods are replaced by enzymatic techniques. The second is an inevitable consequence of the introduction of the halogen (which is tantamount to changing the primary structure of the molecule). The physico‐chemical properties (probably the conformation of the protein) depend on the halogen content and its distribution. In the case of thyroglobulin, two types of change are observed. For fairly low halogen contents, each iodine atom introduced causes an increase in the sedimentation factor (from 17 to 20 S). When the iodine content is increased, the molecule, which has hitherto been broken down by the detergent into sub‐units of 12 S, develops a resistance to this treatment, so that iodination modifies the interaction between sub

ISSN:0022-2135    

DOI:10.1002/jlcr.2590030202

出版商:John Wiley&Sons, Ltd.    

年代:1967

数据来源: WILEY

摘要:

AbstractFerrocene‐59Fe has been prepared with ferric chloride as the limiting reagent. Specific activities of five millicuries per millimole could be readily achieved. Ferrocene was converted to ferrocenylmethyl isothiocyanate and β‐ferrocenylpropionic acid and these compounds were used in metabolic studies as “tags” for a series of synthetic polypeptides with molecular weights in the range of 50‐100,000. Tagging at a level of about 5 microcuries per milligram of peptide obtained by direct reaction of the isothiocyanate with the ε‐amino groups of lysine in a glutamic acid‐lysine‐tyrosine copolymer or by an activated coupling of ferrocenylpropionic acid and the synthetic polypeptide with a carbodiimide derivative. Some observations on the mechanism of tag

ISSN:0022-2135    

DOI:10.1002/jlcr.2590030203

出版商:John Wiley&Sons, Ltd.    

年代:1967

数据来源: WILEY

摘要:

AbstractA method is discussed for the labelling of Diprocon by interchange between131I and inactive Diprocon, obtaining a radiochemical yield over 95% in only five minutes.The effect of pH, temperature and molar relation between the reactants on the radiochemical yield is determined as well as the maximum sterilization time and the optimal storage conditions for the labelled molecule.

ISSN:0022-2135    

DOI:10.1002/jlcr.2590030204

出版商:John Wiley&Sons, Ltd.    

年代:1967

数据来源: WILEY

摘要:

AbstractA six‐step synthesis of tritiated 6α, 9α‐difluroro‐16α‐methy‐11β, 17 α.,21‐trihydroxypregna‐1,4‐diene‐3,20‐dione (5) and 6α.,9α‐difluro‐11β,16α.,17α.,21‐tetrahydroxypregna‐1,4‐diene‐3,20‐dione 16,17‐acetonide (7) from the appropriate Δ.l,4,9(11)‐3‐keto intermediates is described. Isotope incorporation was achieved by selectively reducing the 1,2 and 4,5‐double bonds with tritium gas followed by regeneration of t

ISSN:0022-2135    

DOI:10.1002/jlcr.2590030205

出版商:John Wiley&Sons, Ltd.    

年代:1967

数据来源: WILEY

摘要:

AbstractDL‐erythro‐sphingosine and DL‐threo‐sphingosine specifically labelled with3H in positions 4 and 5 were prepared. The synthesis of these compounds was based on a modification of a procedure published by Grob and Gadient. Quantitative separation of the sphingosines from acetylenic impurities was accomplished, and the physical constants of pure DL‐erythro and threo sphingosines were determined. D‐erythro sphingosine was prepared by resolving the DL racemate and it was found identical to the naturally occurr

ISSN:0022-2135    

DOI:10.1002/jlcr.2590030206

出版商:John Wiley&Sons, Ltd.    

年代:1967

数据来源: WILEY

摘要:

AbstractOn décrit les effets d'une décharge électrique de haute fréquence dans le méthane ‐14C pur et en mélange avec les halogènes. Une fraction importante du radiocarbone est fixée dans des hydrocarbures de C2à C4, ainsi que dans les halogénures substitués du méthane. L'activité spécifique des composés marqués est celle du mé

ISSN:0022-2135    

DOI:10.1002/jlcr.2590030207

出版商:John Wiley&Sons, Ltd.    

年代:1967

数据来源: WILEY

摘要:

AbstractDeoxyribosides of thymine and uracil labelled with14C of specific activity identical with that of the original radioactive base were prepared by single‐step enzymatic synthesis. When employing 2‐deoxy‐α‐D‐riboso‐l‐phosphate of dicyclohexylamine salt, the enzymatic preparation isolated from Escherichia coli B gives satisfactory yields in the synthesis of both deoxyribonucleosides. Studies were made of the time course of reactions, as well as of the effects of some components on the yields. It has been found that the enzymatic preparation from Escherichia coli B facilitates the transfer of the deoxyribosylase group between thymine and thymidine. The employed technique separation allows preparation of radioactive uracil and thymine deoxyribosides of a radiochemical purity exceedi

ISSN:0022-2135    

DOI:10.1002/jlcr.2590030208

出版商:John Wiley&Sons, Ltd.    

年代:1967

数据来源: WILEY

摘要:

AbstractIn the biosynthesis of labeled S‐adenosylmethionine and S‐adeno‐sylethionine from the corresponding14C‐labeled sulfur amino acids by yeast, some radioimpurity occurred by non‐specific labeling of the sulfonium compounds. This is explained by partial degradation of methionine and ethionine in the yeast cells, followed by utilization of the randomized fragments in the biosynthesis. The degree of mislabeling remains low because endogenous methionine synthesis from metabolic pool constituents is suppressed by the excess of methionine and ethionine supplement in the culture medium. Hydrolysis of the sulfonium compounds and analysis of the fragments showed that the misplaced isotope amounts to approximately 0.5% in the adenine, and 0.2% in the homoserine part compared with the total radioactivity of the sulfonium compoun

ISSN:0022-2135    

DOI:10.1002/jlcr.2590030209

出版商:John Wiley&Sons, Ltd.    

年代:1967

数据来源: WILEY

ISSN:0022-2135    

DOI:10.1002/jlcr.2590030210

出版商:John Wiley&Sons, Ltd.    

年代:1967

数据来源: WILEY

摘要:

AbstractAn excellent communication dealing with the enzymatic preparation of deoxyribonu‐. cleosides labelled with14C in the base, using a crude enzyme extract of Lactobacillus helveticus has been published in this Journal (1) quite recently by Cardinaud and Viswanthan. The most important result was a high degree of conversion of pyrimidine bases to the corresponding deoxyribosides.In connection with this work we wish to present some observations from the same field made in our Laboratory (2). It was the purpose of our work to isolate the enzyme trans‐N‐deoxyribosylase from a Lactobacillus helveticus culture grown just in sterile milk without any additives, to test the enzymatic activity of the isolated enzyme and its suitability for rapid enzymatic synthesis of deoxyribonucleosides labelled with radiocarb

ISSN:0022-2135    

DOI:10.1002/jlcr.2590030211

出版商:John Wiley&Sons, Ltd.    

年代:1967

数据来源: WILEY