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1.
《Ibis》1930,72(S1):532-543
An easily recognized little bird in both of its very different seasonal dresses: one with no very near relative among the other species, but thoroughly Cirticoline from every point of view, alive or on the table: about the size of the Wood-Warbler (P. sibilatrix) , but with a shorter tail and much shorter wings, (totally different coloration), and in behaviour more like a bush-loving Sylvia , the Whitethroat (S. communis) for instance, only without any of that bird's aerial love-dances.  相似文献   

2.
Human cytomegalovirus. III. Virus-induced DNA polymerase.   总被引:47,自引:25,他引:22       下载免费PDF全文
Infection of WI-38 human fibroblasts with human cytomegalovirus (CMV) led to the stimulation of host cell DNA polymerase synthesis and induction of a novel virus-specific DNA polymerase. This cytomegalovirus-induced DNA polymerase was purified and separated from host cell enzymes by DEAE-cellulose and phosphocellulose column chromatographies. It can be distinguished from host cell enzymes by chromatographic behavior, template primer specificity, sedimentation property, and the requirement of salt for maximal activity. This virus-induced enzyme has a sedimentation coefficient of 9.2S and is found in both the nuclei and cytoplasm of virus-infected cells, but not in uninfected cells. This enzyme could efficiently use activated calf-thymus DNA, oly(dA)-oligo(dT)12-18, and poly(dC)-oligo(dG)12-18 as template primers, especially poly(dA)-oligo(dT)12-18, but it could not use poly(rA)-oligo(dT)12-18, poly(rC)-oligo(dG)12-18, or oligo(dT)12-18. The enzyme requires Mg2+ for maximal activity, is sensitive to p-hydroxymercuribenzoate, and is not a zinc metalloenzyme. In addition, the cytomegalovirus-induced DNA polymerase activity can be enhanced by adding 0.06 to 0.12 M NaCl or 0.03 to 0.06 M (NH4)2SO4 to the reaction mixture.  相似文献   

3.
J Murray  B Clarke 《Heredity》1976,37(2):253-269
The general colour of the shell in Partula taeniata is controlled by at least two loci. One of these (C) has a series of six alleles which determine the yellow (Y) and neutral brown (N) series of colours. Alleles for darker colours are dominant to those for lighter colours, but dominance is not always complete. The pink (P) colours are determined by a second locus (P) which modified the expression of the lighter alleles of the C locus. Orangeshell colour segregates with yellow but its allelic relationship is unknown. Colour of the lip is controlled by a locus (L) with pink lip dominant to white lip. The colour of the spire is determined by a locus (S) with dark (N4) spire dominant to light spire. An intermediate spire colour shows the same pattern of inheritance and may represent the effect of another allele. Banding of the shell is dominant to absence of bands, with two loci (B1 and B2) determining the type of banding. An allele at B1 produces the frenata pattern; an allele at B2 produces zonata; together they produce lyra. All the loci for which linkage data are available are linked so strongly that the whole array may be considered a supergene. Self-fertilisation takes place primarily during early reproductive life. About 20 per cent of the young of the first mating of an individual are produced by selfing, but over the whole reproductive span the frequency is only about 2-5 per cent. There is inconclusive evidence for heterozygote advantage of banded individuals.  相似文献   

4.
T S Li  Y L Li  X T Liang 《Steroids》1992,57(2):67-71
13,17-Secodiacholestanes (6) were synthesized from cholesterol (1) in six steps. The key intermediates, (20R)- and (20S)-diacholest-13(17)-enes (3a and 3b), underwent ozonization and reduction to provide (20R)- and (20S)-13,17-secodiacholesta-13,17-dione (5a and 5b), respectively. On Clemmensen reduction, the diones (5a and 5b) yielded the target molecule 6. The structure of an unknown biomarker was shown to be different from the proposed 6 by gas chromatographic/mass spectrometric comparison.  相似文献   

5.
Rats were exposed under aerobic or hypoxic conditions to 200-1200 rads of 60Co gamma-rays or extended-Bragg-peak helium ions on the eighth day of gestation. Uterine contents were examined on the twentieth day of gestation. At the 50 per cent embryonic survival level, helium ion r.b.e. was 1(.0) (aerobic) and 1(.2) (hypoxic). Maximum attainable gamma-ray and helium-ion o.e.r.s. were 2(.2) and 1(.7) respectively, indicating an oxygen-effect gain (o.e.g.) of 1(.2). At the 10 per cent survival level helium ion r.b.e. was 1(.1) (aerobic) and 1(.4) (hypoxic). Gamma-ray and helium-ion 0.e.r.s. were 2(.0) and 1(.5) respectively, indicating a helium ion o.e.g. of 1(.3). These data demonstrate that the small fraction of high-LET radiation present in this helium ion beam has a neglible effect on the aerobic r.b.e., but lowers the effective o.e.r. of the beam approximately 25 per cent relative to that of gamma-rays. Helium ions were significantly more effective than gamma-rays in killing embryos under hypoxic conditions, in producing congenital abnormalities under aerobic conditions, and in stunting foetal growth under both conditions.  相似文献   

6.
The glycolipids of Lactobacillus casei A.T.C.C. 7469   总被引:1,自引:0,他引:1  
1. The lipids were extracted from Lactobacillus casei A.T.C.C. 7469 with chloroform-methanol mixtures. The glycolipids were obtained by chromatography on silicic acid and DEAE-cellulose (acetate form). 2. Hydrolysis of the glycolipids with alkali gave two glycerol glycosides and a mixture of fatty acids. 3. The glycosides were separated and their structures elucidated. The major component was O-alpha-d-galactopyranosyl-(1-->2)-O-alpha-d-glucopyranosyl-(1-->1)-glycerol and the minor component O-alpha-d-glucopyranosyl-(1-->6)-O-alpha-d-galactopyranosyl-(1-->2)-O-alpha-d-glucopyranosyl-(1-->1)-glycerol. 4. Analysis of the fatty acids by gas-liquid chromatography showed that they were predominantly palmitic acid, octadecenoic acid and lactobacillic acid.  相似文献   

7.
GTP-AMP phosphotransferase has been purified 116-fold with a yield of 24% from beef heart mitochondria using freeze-thawing, alkali and acid treatment and successive column chromatography on phosphocellulose, Sephadex G-100 and blue-dextran--Sepharose. It has crystallized from poly-(ethylene glycol) and is essential homogeneous by sodium dodecylsulfate electrophoresis and isoelectrofocusing. The specific activity of the crystalline preparation was 290 U/mg. The molecular weight was found to be 26000 and the isoelectric point to be 9.8. Amino acid analysis showed 21 aspartic acid or asparagine, 19 threonine, 12 serine, 26 glutamic acid or glutamine, 15 proline, 16 glycine, 14 alanine, 15 valine, 4 methionine, 12 isoleucine, 28 leucine, 7 tyrosine, 7 phenylalanine, 5 histidine, 14 lysine, 16 arginine, 2 tryptophan, no --SS-- bonds or free --SH. Guanosine(5')pentaphospho(5')adenosine is a very strong inhibitor similar to adenosine(5')pentaphospho(5')adenosine as an inhibitor of cytosolic adenylate kinase.  相似文献   

8.
Reactions of OH radicals with methyl and ethyl derivatives of uracil, cytosine and thymine in aqueous solutions have been investigated. Photolysis of H2O2 was used to generate OH radicals and the radicals on the base derivatives were spin-trapped using t-nitrosobutane and identified with the help of e.s.r. spectroscopy. Addition of OH radicals was found to take place predominantly to the C(5)--C(6) double bond of the bases. H-abstraction from the methyl group occurred in the N(1) methyl derivatives of uracil, cytosine and thymine. Radicals formed by H-abstraction from the methyl group were also detected for 3-methyluracil, thymine, 1-methylthymine and 1-ethylthymine. Introduction of a methyl or ethyl group at the N(1) position of uracil, cytosine and thymine causes an increase in the C(6) proton coupling and a decrease in the N(1) splitting for radicals formed by OH addition at the C(5) position.  相似文献   

9.
Under brief consideration is the problem of primary or secondary status of the judgments about taxa relative to the judgments about characters in the biological classifications. The following formal definition of taxonomic system (classification) TS is provided: TS = BT[T, C(t), R(t), R(c), R(tc)], where BT is a biological theory constituting content-wise background of the system, T is a set of taxa, C(t) is a set of taxonomic characters, R(t) is a set of relationships among taxa (similarity, kinship, etc.), R(c) is a set of relationships among characters (homology, etc.), and R(tc) is a set of correspondences among taxa and characters. The latter correspondences may be complete or incomplete. At ontological level, there two basical traditions exist in biological systematics regarding R(tc) according to which the biological diversity is patterned either as a set of groups of organisms (taxa) or as a set of their properties (characters). In the first case, taxon is "primary" relative to character (in cladistics); in its opposite, character is "primary" relative to taxon (in scholasticism, classical typology, classical phylogenetics). At epistemological level, incompleteness of the taxon-character correspondence makes classificatory procedure iterative and taxonomic diagnoses context-dependent. The interative nature of classificatory procedure makes the "primary" or "secondary" status of both taxa and characters relative and alternating. This makes it necessary to introduces a kind of uncertainty relation in biological systematics which means impossibility of simultaneous definition of both extensional and intentional parameters of the taxonomic system at each step of classificatory iterations.  相似文献   

10.
Varve chronologies are of several kinds but glacial varves respond to summer temperature and fluvial varves to summer rainfall.Tree-ring chronologies near the timberline respond to summer temperature but European oak chronologies respond to summer rainfall.Certain global features of the weather of the summer season, notably the Biennial Index, are therefore parameters that can be used for cross-dating both varves and tree-rings in different continents.Characteristic curves for different parameters in the Late Glacial (Zones Ia, Ib and II) and in the past thousand years are presented. A moisture curve is given for the North European Plain (200 B.C.–A.D. 1100). A conversion chart for tree-rings and radiocarbon dates is extended back into the Late Glacial on the tentative assumption that the radiocarbon error was about 950 years at the beginning of the Holocene (III/IV), i.e. that 10300 b.p. should be 11250 B.P. or 9300 B.C.Supplementary sources of information useful in obtaining approximate dates include: (a) palaeomagnetism; (b) tephrochronology and X-ray analysis; (c) cycle analysis; (d) climatic peculiarities associated with specific radiocarbon centuries; (e) X-ray analysis of specific varves; and (f) new methods of varve-analysis.The varve-series used for the Late Glacial, if the author's cross-dating between North America and Scandinavia is acceptable, constitute a floating chronology of about 4000 years. Given approximate 14C dates for any long series of varves or tree-rings in one part of the world, it is now possible to obtain cross-dating with any other long series in another part of the world, and it will be easy to replace the tentative ‘950-year’ error by a precise figure determined from a combined varve and tree-ring scale extending back from the present day to (say) the zero of Sauramo's scale for varves in Finland. In the meantime the ‘950’ is mnemonically convenient, as this would make the year on the B.C. scale one thousand less than the year on the b.p. scale.  相似文献   

11.
Models of parent-offspring conflict. II. Promiscuity   总被引:3,自引:0,他引:3  
The population genetics of Trivers (1974) concept of parent-offspring is examined for species in which the effects of the conflict are felt by future half-sibs, as in promiscuous mating systems in which the male shows no parental care. Whether or not a rare conflictor gene will spread in a non-conflictor population depends on f(m) greater than (m + 1)/(0.5m + 1.5) for a dominant gene, and on f(m) greater than 1/4(7 + 3) for a recessive gene; f(m) is the fitness gained by a conflictor relative to a non-conflictor offspring [f(m) greater than 1], and m is the amount of parental investment taken by a conflictor relative to m = 1 for a non-conflictor. The ESS value for conflict (mo) in promiscuous species with zero male parental care has mo = f(mo)/4[df(mo)/dmo]. However, where the male maintains the same harem for several breeding seasons, or where there is promiscuity but both sexes contribute equally to parental care, conditions for conflict are equivalent to monogamy.  相似文献   

12.
Epstein-Barr virus (B95-8) DNA consists of short (10 X 10(6)) and long (87 X 10(6)) unique DNA sequences joined by 10 tandem reiterations of a 1.85 X 10(6) DNA segment. The reiterated sequence contains BamI and BglII sites separated by 4 X 10(5). The 4.5 X 10(5) and 14.0 X 10(5) segments generated by cleavage of the reiterated DNA with BamI and BglII contain sequences which hybridize to each other, suggesting that the internal tandemly reiterated sequence has a direct or inverted repeat within it. The opposite ends of the linear, nicked, double-stranded DNA molecule (R. F. Pritchett, S. D. Hayward, and E. D. Kieff, J. Virol. 15:556--569, 1975) consist of from 1 to 12 direct repeats of another 3 X 10(5) sequence (D. Given and E. Kieff, J. Virol. 28:524--542, 1978; D. Given, D. Yee, K. Griem, and E. Kieff, J. Virol. 30:852--862, 1979). There is no homology between the internal reiterated sequence and either terminus. However, part of the internal reiteration (less than 5 X 10(5) is reiterated at two separate locations in the long unique region. The internal reiterations are a source of variation within EBV (B95-8) DNA preparations. Thus, although the majority of molecules contain 10 tandem reiterations, some molecules have 9, 8, 7, 6, 5, 4, or fewer tandem reiterations. A consequence of this variability is that the KpnI A fragment and the EcoRI/Hsul A fragment consist of a family of seven or more fragments differing in the number of tandem internal reiterations. The EcoRI/HsuI A fragment of EBV (W91) DNA is approximately 6 X 10(6) smaller than the largest and dominant EcoRI/HsuI A fragment of EBV (B95-8) DNA. EBV (W91 DNA also differs from EBV (B95-8) DNA by an additional 7 X 10(6) to 8 X 10(6) of DNA in the long unique DNA region (D. Given and E. Kieff, J. Virol. 28:524--542, 1978; N. Raab-Traub, R. Pritchett, and E. Kieff, J. Virol. 27:388--398, 1978). These data suggest the possibility that the smaller number of internal reiterations in EBV (W91) DNA may be a consequence of the additional unique DNA and a restriction in the overall size of EBV DNA.  相似文献   

13.
The spectrum of inositol phosphate isomers present in avian erythrocytes was investigated in qualitative and quantitative terms. Inositol phosphates were isolated in micromolar quantities from turkey blood by anion-exchange chromatography on Q-Sepharose and subjected to proton n.m.r. and h.p.l.c. analysis. We employed a h.p.l.c. technique with a novel, recently described complexometric post-column detection system, called 'metal-dye detection' [Mayr (1988) Biochem. J. 254, 585-591], which enabled us to identify non-radioactively labelled inositol phosphate isomers and to determine their masses. The results indicate that avian erythrocytes contain the same inositol phosphate isomers as mammalian cells. Denoted by the 'lowest-locant rule' [NC-IUB Recommendations (1988) Biochem. J. 258, 1-2] irrespective of true enantiomerism, these are Ins(1,4)P2, Ins(1,6)P2, Ins(1,3,4)P3, Ins(1,4,5)P3, Ins(1,3,4,5)P4, Ins(1,3,4,6)P4, Ins(1,4,5,6)P4, Ins(1,3,4,5,6)P5, and InsP6. Furthermore, we identified two inositol trisphosphate isomers hitherto not described for mammalian cells, namely Ins(1,5,6)P3 and Ins(2,4,5)P3. The possible position of these two isomers in inositol phosphate metabolism and implications resulting from absolute abundances of inositol phosphates are discussed.  相似文献   

14.
Identification of new psychoactive substances (NPS) in biological and non-biological samples represents a hard challenge for forensic toxicologists. Their great chemical variety and the speed with which new NPS are synthesised and spread make stringent the need of advanced tools for their detection based on multidisciplinary approaches. For this reason, in August 2016, the “Unit of Research and Innovation in Forensic Toxicology and Neuroscience of Addiction” (U.R.I.To.N.) was founded by the Forensic Toxicology Division of the University of Florence. In this Research Unit, various professionals (i.e. forensic toxicologists, chemists, physicians) collaborate to study all the aspects of drugs of abuse, especially NPS. Herein, we describe the multidisciplinary approach comprising liquid chromatography coupled to tandem mass spectrometry (LC–MS/MS), gas chromatography hyphenated to mass spectrometry (GC–MS) and solution nuclear magnetic resonance analysis that allowed the identification of three NPS such as 1-(benzofuran-5-yl)-N-methylpropan-2-amine, 2-amino-1-(4-bromo-2,5-dimethoxyphenyl)ethan-1-one (bk-2C-B), and 3-(2-aminopropyl)indole (α-methyltryptamine) in seized materials.  相似文献   

15.
Glycogen synthase (UDP glucose: glycogen alpha-4-glycosyltransferase, EC2.4.1.11) of the tapeworm Hymenolepis diminuta exists in 2 forms: 1) the I-form (independent), which has significant activity in the absence of glucose 6-phosphate (G6P); and 2) the phosphorylated D-form (dependent), which has no enzymatic activity unless G6P is present. The activity of the I-form is greatly enhanced by a variety of allosteric effectors which have, as their common feature, 1 or more phosphate groups. These include inorganic phosphate (Pi), several sugar phosphates, some phosphorylated glycolytic intermediates, and nucleoside mono- and triphosphates. Competition studies suggest that while most of the positive effectors act at the same site on the enzyme (the "G6P site"), fructose 1,6-diphosphate (FDP) and 2,3-diphosphoglyceric acid (2,3DPG) act at low concentrations to stimulate the enzyme at another locus (the "diphosphate site"), while at high concentrations they competitively inhibit the binding of G6P and of the other activators. The inhibition by high uridine monophosphate (UMP) concentrations is competitive only with the activator uridine triphosphate (UTP), suggesting the existence of a third type of allosteric site (the "uridine nucleotide site"). This third site may be the locus for feedback inhibition by the product uridine diphosphate (UDP), a control mechanism which has been observed to occur in mammalian systems. The allosteric control of the D-form of the enzyme is comparatively simple, apparently involving only one site (the "G6P site") that binds a few effects with greatly reduced affinity. Pi reverses the activation of the D-form by G6P.  相似文献   

16.
According to Wang and Xie, their recently published genus Trirostellum is distinguished from its allied genera by a number of characteristics: (1) the stamens with their filaments coherent into a central column; (2) the female flowers possessing rudimentary stamens; (3) the ovary 3-celled, with one ovule in each cell; (4) the fruits dehiscent, 3-rostrated at the apex; (5) the fruits possessing persistent perianth; (6) the seeds tuberculate and winged. However, upon a careful comparison of Trirostellum yixingensis Z.P. Wang et Q. Z. Xie, the type species of Trirostellum with Gynostemma pentaphyllum (Thunb.) Mak., the type species of Gynostemma Bl. and some other species of Gynostemma as well,we have found that the representatives of the above two genera are identical in most of the important diagnostic characteristics except that the fruits of the former genus are dehiscent with three long beaks at the apex, while the fruits of the latter genus are indehiscent with very short beaks. Besides, results obtained from chromosome counting haove shown that the somatic chromosome number of Trirostellum yixingensis is 2n=22, while that of Gynostemma pentaphyllum is 2n=28.Yet these morphological and chromosomal differences seem not sufficient for generic demarcation. We, therefore, suggest that Trirostellum bereduced to a sectional or subgeneric rank of Gynostemma Bl.  相似文献   

17.
Sulfate-reducing bacteria with oval to rod-shaped cells (strains AcRS1, AcRS2) and vibrio-shaped cells (strains AcRM3, AcRM4, AcRM5) differing by size were isolated from anaerobic marine sediment with acetate as the only electron donor. A vibrio-shaped type (strain AcKo) was also isolated from freshwater sediment. Two strains (AcRS1, AcRM3) used ethanol and pyruvate in addition to acetate, and one strain (AcRS1) grew autotrophically with H2, sulfate and CO2. Higher fatty acids or lactate were never utilized. All isolates were able to grow in ammonia-free medium in the presence of N2. Nitrogenase activity under such conditions was demonstrated by the acetylene reduction test. The facultatively lithoautotrophic strain (AcRS1), a strain (AcRS2) with unusually large cells (2×5 m), and a vibrio-shaped strain (AcRM3) are described as new Desulfobacter species, D. hydrogenophilus, D. latus, and D. curvatus, respectively.  相似文献   

18.
一株产生漆酶的耐高温膨大拟青霉大孢变种   总被引:7,自引:1,他引:6  
从河北唐山地区的 1份土样中 ,分离到 1株产漆酶、耐高温的拟青霉新分类单元 ,膨大拟青霉大孢变种 [Paecilomycesinflatus (Burnside)Carmichaelvar.majorLiangZ .Q .,ChuH .L .etHanY .F .]。此菌的典型特征是在查氏培养基上 ,4 0℃ ,7d ,菌落直径为 38~ 4 4mm。瓶梗单生 ,不规则的着生在气生菌丝或简单的分生孢子梗上。分生孢子光滑 ,梭形或长椭圆形 ,大多数 (5 .6~ 9.0 ) μm× (2 .5~ 4 .5 ) μm。  相似文献   

19.
A comparative analysis of three Epstein-Barr virus DNAs from American patients with infectious mononucleosis (B95-8, Cherry, and Lamont) and four Epstein-Barr virus DNAs from African patients with Burkitt lymphoma (AG876, W91, Raji, and P3HR-1) indicated that the usual format of Epstein-Barr virus DNA includes a variable number of direct repeats of a 0.35 X 10(6)-dalton sequence (TR) at both ends of the DNA, a 9 X 10(6)-dalton sequence of largely unique DNA (Us), a variable number of repeats of a 2 X 10(6)-dalton sequence (IR), and a 89 X 10(6)-dalton sequence of largely unique DNA (UL). Within UL there was homology between DNA at 26 X 10(6) to 28 X 10(6) daltons and DNA at 93 X 10(6) to 95 X 10(6) daltons. The relative sequence order (TR, US, IR, UL, TR) did not vary among "standard" Epstein-Barr virus DNA molecules of each isolate. B95-8 DNA had an unusual deletion extending from 91 X 10(6) to 100 X 10(6) daltons, and P3HR-1 DNA had an unusual deletion extending from 23.5 X 10(6) to 26 X 10(6) daltons. There was sufficient variability among the EcoRI and BamHI fragments of the DNAs to identify each isolate specifically. However, we discerned no distinguishing features for the two geographic or pathogenic origins of the seven isolates. Three intracellular DNAs (Raji, Lamont, and Cherry) and one virion DNA (P3HR-1) were heterogenous in molecular organization and had subpopulations of rearranged or defective molecules. Some regions, particularly 59 X 10(6) to 63 X 10(6) daltons and sequences around TR, frequently participated in rearrangements. Restriction endonuclease maps of the standard and rearranged DNAs of the seven isolates are presented.  相似文献   

20.
As model compounds for Ni(II)-binding heparin-like compounds isolated from human kidneys (Templeton, D.M. & Sarkar, B. (1985) Biochem. J. 230 35-42.), we investigated two disaccharides--4-O-(2-O-sulfo-alpha-L-idopyranosyluronic acid)-2,5-anhydro- D-mannitol, disodium salt (1a), and 4-O-(2-O-sulfo-alpha-L-idopyranosyluronic acid)-6-O- sulfo-2,5-anhydro-D-mannitol, trisodium salt (1b)--that were isolated from heparin after nitrous acid hydrolysis and reduction. The monosulfate (1a) was active whereas the disulfate (1b) was inactive in a high-performance liquid chromatography (HPLC) binding assay with the tracer ions 63Ni(II) 54Mn(II), 65Zn(II), and 109Cd(II). This result is in accord with the isolation of two 67Cu(II) and 63Ni(II) binding fractions from a complete pool of nitrous-acid-derived heparin disaccharides using sulfate gradients and a MonoQ anion exchange column on an FPLC system. One was identified as compound (1a) and the other as a tetrasulfated trisaccharide by high resolution FAB-MS, NMR and HPLC-PAD. Similarly, two synthetic disaccharides-methyl, 2-O-sulfo-4-O-(alpha-L-idopyranosyluronic acid)-2-deoxy-2-sulfamide-alpha-D-glucosamine, trisodium salt [IdopA2S(alpha 1,4)GlcNS alpha Me, 2a], and 2-O-sulfo-4-O-(alpha-L-idopyranosyluronic acid)-2-deoxy-2-sulfamide-6-O-sulfo- alpha-D-glucosamine, tetrasodium salt [IdopA2S (alpha 1,4)GlcNS6S alpha Me, 2b]--were shown to bind tracer amounts of 63Ni and 67Cu using chromatographic assays. Subsequently, 1H NMR titrations of 1a, 1b, 2a, and 2b with Zn (OAc)2 were analyzed to yield 1:1 Zn(II)-binding constants of 472 +/- 59, 698 +/- 120, 8,758 +/- 2,237 and 20,100 +/- 5,598 M-1, respectively. The values for 2a and 2b suggest chelation. It is suggested that the idopyranosiduronic acid residue is the major metal binding site. NMR evidence for this hypothesis comes from marked 1H and 13C chemical shift changes to the iduronic acid resonances after addition of diamagnetic Zn(II) ions.  相似文献   

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