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1.
A E Albert 《Chemico-biological interactions》1972,4(4):287-296
Continual feeding of either 4-dimethylaminoazobenzene (DAB) or 2-methyl-4-dimethylaminoazobenzene (2-MeDAB) to rats resulted in an increase in the uptake but a decrease in the turnover of [3H]lysine in all the nuclear proteins of rat liver. The pattern of lysine turnover in acidic nuclear proteins from DAB-fed animals was more similar to that of normal acidic nuclear proteins than that from the 2-MeDAB-fed animals. The histone fractions showed an increase in uptake after dye feeding which was greater in the lysine-rich fractions than in the arginine-rich fractions. During DAB feeding both the uptake and rate of turnover of [3H]thymidine were greatly increased, but with the noncarcinogenic 2-MeDAB the uptake of the precursor was lower and the rate of turnover slower than in normal animals. These differences in metabolism in response to azo dye feeding are discussed in relation to azo dye carcinogenesis. 相似文献
2.
2 rat cell lines originated from ascites hepatoma AH66-B and esophageal tumor R1 were examined for their inducibility of sister-chromatid exchanges (SCEs) after treatment with 14 kinds of indirect mutagens/carcinogens, including 6 amine derivatives, 4 azo compounds, 3 aromatic hydrocarbons and 1 steroid. Of the 14 chemicals tested, 2-acetylaminofluorene (AAF), butylbutanolnitrosamine (BBN), dimethylnitrosamine (DMN), cyclophosphamide (CP), urethane, 2-methyl-4-dimethylaminoazobenzene (2-MeDAB), 3′-methyl-4-dimethylaminoazobenzene (3′-MeDAB), 4-o-tolylazo-o-toluidine (4-TT), benzo[a]pyrene (BP), 7,12-dimethyl-benz[a]anthracene (DMBA) and diethylstilbestrol (DES) were estimated to be effective inducers of SCEs in AH66-B and/or R1 cells, without the use of exogenous activating systems. Cell-mediated SCE tests with 6 selected chemicals, CP, 2-MeDAB, 4-TT, BP, DMBA and DES, showed a significant increase of SCEs in Chinese hamster Don-6 cells co-cultivated with AH66-B or R1 cells, depending on the number and sensitivity of AH66-B or R1 cells, as well as on the dose of chemicals tested, whereas singly cultured Don-6 cells were much less sensitive or almost insensitive to these chemicals. The above findings suggest that AH66-B and R1 cells may retain metabolic activities to convert a wide range of indirect mutagens/carcinogens into their active forms to induce SCEs, and that these cell lines provide simple and reliable screening systems in vitro, including the cell-mediated SCE assay, for detection of genotoxic agents, without the use of exogenous activation systems. 相似文献
3.
C E Schwartz T Gabryelak C J Smith J M Taylor J F Chiu 《Biochemical and biophysical research communications》1982,107(1):239-245
The effect of the hepatocarcinogen 3′-methyl-4-dimethylaminoazobenzene on α-fetoprotein (AFP) and albumin gene expression in rat liver was studied. Serum concentrations of AFP and albumin were measured. Amounts of AFP mRNA and albumin mRNA in rat livers were determined by hybridization of total cytoplasmic RNAs to their cDNAs. Dramatic increases in serum AFP concentrations coincided with increases in AFP biosynthesis and amount of AFP mRNA in livers of carcinogen-treated rats. In contrast, no or little change in albumin mRNA concentration was found in livers of rats treated with 3′-methyl-4-dimethylaminoazobenzene. Concomitantly, there was little change in liver albumin biosynthesis or serum albumin concentrations during hepatocarcinogenesis. 相似文献
4.
Chemical carcinogenesis can be characterized by a sequence of events leading to the development of tumors. Selenium (Se) inhibition
of colon, liver, and lung carcinogens is demonstrated. Using the male Sprague Dawley rat model Se inhibited the colon tumor
incidence in 1,2-dimethylhydrazine (DMH) treated rats and reduced the total number of colon tumors in methylazoxymethanol
(MAM) treated rats. Selenium inhibited 2-acetylaminofluorene (AAF) and 3′-methyl-4-dimethylaminoazobenzene (3′-MeDAB) hepatocarcinogenesis.
The hepatic tumor incidence induced by 3′-MeDAB was reduced by both inorganic Se (Na2SeO3) and by organic Se (Se-yeast) supplements.
In vitro systems have been studied in an effort to decipher the inhibitory properties of Se on the multistage origin of tumors
induced by chemical carcinogens. Current studies suggest that the protective effect of Se against AAF hepatocarcinogenesis
may be correlated with a change in AAF metabolism. The mutagenicity of AAF and AAF metabolites inSalmonella typhimurium TA1538 is decreased by Se. Additionally, Se reduced N-t-OH−AAF induction of sister chromatid exchange (SCE) frequencies in
whole blood cultures, and also reduced aryl hydrocarbon hydroxylase activity using benzo(a) pyrene as substrate.
The comparative effects of antioxidants on DMH induction of colon tumors are presented in detail. Supplements of 4 ppm Se
to the drinking water, 1.2% ascorbic acid (V
c
) to the diet or 0.5% butylated hydroxytoluene (BHT) to the diet of DMH-treated rats reduced the colon tumor incidence of
DMH controls from 64 to 31% (Se), 38% (V
c
), and 43% (BHT). The colon tumor incidence in DMH-treated rats receiving a combination of Se+V
c
increased to 83%, while the combination of Se+BHT decreased the colon tumor incidence to 55%. The growth and survival of
rats provided long-term supplements of 4 ppm Se in the drinking water are compared with untreated controls. 相似文献
5.
The incorporation of [3H]thymidine into DNA due to unscheduled DNA synthesis (UDS) induced by N-OH-2-acetylaminofluorene (N-OH-AAF), aflatoxin B1 (AFB1), ethyl methanesulfonate (EMS) and ultra-violet light was quantitated by autoradiography and by scintillation spectrometry on acid precipitable macromolecules or DNA insolated by isopycnic banding in cesium chloride (CsCl). Dose-dependent increases in UDS due to N-OH-AAF and AFB1 treatment were found. Only 2-fold increases at the highest dose levels were found, however, when incorporated [3H]thymidine was quantitated by scintillation spectrometry. Seven, 11, and 25-fold increases in UDS induced by AFB1, N-OH-AAF and ultra-violet light, respectively, were found when incorporated [3H]thymidine was quantitated by autoradiography, indicating a high sensitivity for detecting ‘long patch’ repair by this technique. Scintillation spectrometry was completely ineffective in detecting EMS-induced UDS, whereas autoradiography demonstrated a small, but significant induction in [3H]thymidine incorporation at high dose levels. The non-proliferative nature of the primary hepatocyte prohibits the uniform radioactive prelabeling of DNA, necessary in other techniques, for the detection of ‘short patch’ repair induced by compounds such as EMS. Therefore, the sensitivity of the primary cultured rat hepatocyte in conjunction with UDS for detecting DNA damage caused by mutagens and carcinogens which induce ‘short patch’ repair may be limited to the autoradiographic analysis of the unscheduled incorporation of [3H]thymidine. 相似文献
6.
The effects of post-treatments with caffeine in G2 on the frequency of chromosomal aberrations induced by thiotepa, mitomycin C and N-methyl-N-nitro-N′-nitrosoguanidine were studied in human lymphocytes. Caffeine was found to potentiate the frequency of chromatid aberrations induced by all 3 S-dependent agents tested; the most striking enhancement being obtained when caffeine was present during the last 1.5 h before harvesting. Post-treatments in G2 with 3-aminobenzamide had no influence on the aberration frequency induced by thiotepa and N-methyl-N-nitro-N′-nitrosoguanidine. 相似文献
7.
Certain carcinogens have an effect on the activity of pancreatic deoxyribonuclease I (DNAase I, EC 3.1.4.5). The effect of two potent mycocarcinogens, viz. aflatoxin B1 and sterigmatocystin, as well as the weak carcinogen, aflatoxin B2, on the activity of two nuclear DNAases (DNAases I and II) from rat liver was therefore investigated. 相似文献
8.
《Animal : an international journal of animal bioscience》2020,14(2):339-345
Cows undergoing a negative energy balance (NEB) often experience a state of immunosuppression and are at greater risk of infectious diseases. The present study aimed to evaluate the impact of a folic acid and vitamin B12 supplement and feed restriction on several immune parameters. Sixteen cows at 45 ± 3 days in milk were assigned to 8 blocks of 2 cows each according to each cow’s milk production in the previous week, and within each block, the cows randomly received weekly intramuscular injections of either saline or 320 mg of folic acid and 10 mg of vitamin B12 for 5 weeks. During week 5, the cows were fed 75% of their ad libitum intake for 4 days. Blood samples were taken before the beginning of the experiment, just before feed restriction and after 3 days of feed restriction, in order to evaluate blood cell populations, the phagocytosis capacity and oxidative burst of polymorphonuclear leukocytes (PMNs), the proliferation of peripheral blood mononuclear cells (PBMCs) and concentrations of non-esterified fatty acids (NEFAs) and β-hydroxybutyrate. The vitamin supplement did not affect any of the tested variables except milk fat and lactose content. Feed restriction reduced milk production and increased the concentration of NEFAs. Feed restriction did not affect blood cell populations but did reduce the percentage of PMN positive for oxidative burst after stimulation with phorbol 12-myristate 13-acetate. The proliferation of PBMCs was reduced when the cell culture medium was supplemented with sera collected during the feed restriction. In conclusion, feed restriction affected the functions of PMN and PBMC and this effect was not prevented by the folic acid and vitamin B12 supplement. These results support the hypothesis that the greater risk of infectious diseases in cows experiencing a NEB is related to impaired immune cell functions by high circulating concentration of NEFAs. 相似文献
9.
Takeshi Hirano Akinori Sakai Hiroshi Kasai 《Biochemical and biophysical research communications》2009,387(2):316-320
Alcohol consumption is known to have opposing effects on carcinogenesis: promotion and prevention. In this study, we examined the effects of 12% ethanol on oxidative DNA damage accumulation and its repair in mouse livers treated with 3′-methyl-4-dimethylaminoazobenzene (3′-MeDAB), a well-known hepatic carcinogen. We previously reported that 3′-MeDAB increased 8-hydroxyguanine (8-OH-Gua) accumulation and its repair activity, accompanied by the fragmentation of 8-oxoguanine DNA glycosylase 1 (OGG1), the main repair enzyme of 8-OH-Gua. The present results showed that 12% ethanol intake attenuated the 8-OH-Gua accumulation, but not the fragmentation of OGG1 induced by 3′-MeDAB. Additionally, no significant changes in oxidative status, as monitored by lipid peroxidation (LPO), were observed among the 3′-MeDAB-treated mouse livers with/without alcohol administration. These findings suggested that 12% ethanol consumption may reduce the risk of 3′-MeDAB-induced carcinogenesis by decreasing 8-OH-Gua accumulation. 相似文献
10.
Yasukiyo Umemura Tadashi Inoue Masamichi Takagi 《Bioscience, biotechnology, and biochemistry》2013,77(7):1269-1273
The aim of this research was to examine the inhibitory effect of aflatoxin B1, one of the most potent hepatocarcinogen, on the translational step in mouse liver. It has been shown that polysomes were released in vitro from microsomal membrane prepared from rat liver by incubation with aflatoxin B1 and that this release of ribosomes was prevented by addition of corticosterone in the incubation medium.In this paper, the same phenomenon was proved to occur in vivo by an improved fractionation methods, in which ribosome-distributions can be analyzed quantitatively, not only between free and membrane-bound states but also between monosomes and polysomes. Administration of aflatoxin B2 to mice induced reductions of membrane-bound ribosomes and polysomes, with concomitant increases of free ribosomes and monosomes in liver. Simultaneous administration of corticosterone prevented this alteration of ribosome-distributions.From these results, it was deduced that a release of polysomes from membrane occurred primarily by administrating aflatoxin, which then caused a shortening of half-life of mRNA on polysomes, resulting in an increase of the amount of monosomes. 相似文献
11.
Li Chen Qun Yue Yan Li Xuemei Niu Meichun Xiang Wenzhao Wang Gerald F. Bills Xingzhong Liu Zhiqiang An 《Applied and environmental microbiology》2015,81(5):1550-1558
Pneumocandins produced by the fungus Glarea lozoyensis are acylated cyclic hexapeptides of the echinocandin family. Pneumocandin B0 is the starting molecule for the first semisynthetic echinocandin antifungal drug, caspofungin acetate. In the wild-type strain, pneumocandin B0 is a minor fermentation product, and its industrial production was achieved by a combination of extensive mutation and medium optimization. The pneumocandin biosynthetic gene cluster was previously elucidated by a whole-genome sequencing approach. Knowledge of the biosynthetic cluster suggested an alternative way to produce exclusively pneumocandin B0. Disruption of GLOXY4, encoding a nonheme, α-ketoglutarate-dependent oxygenase, confirmed its involvement in l-leucine cyclization to form 4S-methyl-l-proline. The absence of 4S-methyl-l-proline abolishes pneumocandin A0 production, and 3S-hydroxyl-l-proline occupies the hexapeptide core''s position 6, resulting in exclusive production of pneumocandin B0. Retrospective analysis of the GLOXY4 gene in a previously isolated pneumocandin B0-exclusive mutant (ATCC 74030) indicated that chemical mutagenesis disrupted the GLOXY4 gene function by introducing two amino acid mutations in GLOXY4. This one-step genetic manipulation can rationally engineer a high-yield production strain. 相似文献
12.
From the unripe seeds of Cassia torosa three new dimeric hydroanthracene derivatives were isolated along with stigmasterol, sitosterol, campesterol, physcion-9-anthrone, torosachyrsone and the phlegmacins A2 and B2. The structures of the new derivatives were established as physcion-10, 10′-bianthrone, anhydrophlegmacin B2 [2-(6′-methoxy-3′-methyl-3′, 8′, 9′-trihydroxy-1′-oxo-1′, 2′, 3′, 4′-tetrahydroanthracene-10′-yl)-1, 8-dihydroxy-3-methoxy-6-methyl-9-oxo-9, 10-dihydroanthracene] and torosanin [2-(6′-methoxy-3′-methyl-3′, 8′,9′-trihydroxy-1′-oxo-1′, 2′, 3′,4′-tetrahydroanthracene-5′-yl)-1, 8-dihydroxy-3-methoxy-6-methyl-9-oxo-9, 10-dihydroanthracene], respectively. 相似文献
13.
W.K. Lutz W. Jaggi J. Lüthy P. Sagelsdorff C. Schlatter 《Chemico-biological interactions》1980,32(3):249-256
[14C]Aflatoxin B1 (AFB1) was isolated from cultures of Aspergillus parasiticus grown on [1-14C]sodium acetate. Covalent binding of AFB1 to liver DNA of rat and mouse was determined 6–8 h after oral administration. The effectiveness of covalent binding, expressed as DNA binding per dose in the units of a ‘Covalent Binding Index’ (CBI), (μmol aflatoxin/mol DNA nucleotides)/(mmol aflatoxin/kg animal), was found to be 10 400 for rats and 240 for mice. These CBI partly explain the different susceptibility of the two species for the incidence of hepatic tumors.The corresponding values for pig liver DNA, 24 and 48 h after oral administration, were found to be as high as 19 100 and 13 300. DNA-binding has not so far been reported for this species although it could represent an appropriate animal model for studies where a human-like gastrointestinal tract physiology is desirable.Aflatoxin M1 (AFM1) is a metabolite found in the milk of cows that have been fed AFB1-contaminated diet. [14C]AFM1 was also found to be produced by cultures of A. parasiticus giving a yield of about 0.3% of the total aflatoxins. A test for covalent binding to rat liver DNA revealed a CBI of 2100 showing that AFM1 must also be regarded as a strong hepatocarcinogen. It is concluded that AFB1 contaminations should be avoided in dairy feed. 相似文献
14.
Toshihiko Kinjo Yoshino Ashida Hiroshi Higashi Satoshi Sugimura Miho Washida Hiroki Niihara Kiyokazu Ogita Yukio Yoneda Nobuyuki Kuramoto 《Neurochemical research》2018,43(1):70-79
Mitochondrial permeability transition pore (PTP) is supposed to at least in part participate in molecular mechanisms underlying the neurotoxicity seen after overactivation of N-methyl-d-aspartate (NMDA) receptor (NMDAR) in neurons. In this study, we have evaluated whether activation of GABAB receptor (GABABR), which is linked to membrane G protein-coupled inwardly-rectifying K+ ion channels (GIRKs), leads to protection of the NMDA-induced neurotoxicity in a manner relevant to mitochondrial membrane depolarization in cultured embryonic mouse cortical neurons. The cationic fluorescent dye 3,3′-dipropylthiacarbocyanine was used for determination of mitochondrial membrane potential. The PTP opener salicylic acid induced a fluorescence increase with a vitality decrease in a manner sensitive to the PTP inhibitor ciclosporin, while ciclosporin alone was effective in significantly preventing both fluorescence increase and viability decrease by NMDA as seen with an NMDAR antagonist. The NMDA-induced fluorescence increase and viability decrease were similarly prevented by pretreatment with the GABABR agonist baclofen, but not by the GABAAR agonist muscimol, in a fashion sensitive to a GABABR antagonist. Moreover, the GIRK inhibitor tertiapin canceled the inhibition by baclofen of the NMDA-induced fluorescence increase. These results suggest that GABABR rather than GABAAR is protective against the NMDA-induced neurotoxicity mediated by mitochondrial PTP through a mechanism relevant to opening of membrane GIRKs in neurons. 相似文献
15.
Relationships between biotin and vitamin B12. Effects of biotin and vitamin B12 on folic acid metabolism 总被引:2,自引:2,他引:0
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1. The effects of dietary biotin compared with vitamin B12 on the total content and on the distribution of the various folate derivatives in the liver of rats given a biotin-free diet have been studied. The effect of both vitamins on the conversion in vitro of folic acid into citrovorum factor in the same experimental conditions was also examined. 2. In biotin-treated rats as well as in vitamin B12-treated rats the total content of folic acid-active substances measured microbiologically by Pediococcus cerevisiae, Streptococcus faecalis and Lactobacillus casei is significantly higher than that in biotin-deficient rats. The liver distribution of various folate derivatives in the three groups of animals is also markedly modified. 3. The amount of citrovorum factor formed in systems with liver homogenate of rats receiving biotin or vitamin B12 is higher than that with liver homogenates of deficient rats. 4. The results obtained demonstrate the influence of biotin in the metabolism of folic acid, and the similar actions at this level of both biotin and vitamin B12. These results are discussed in relation to the participation of the two vitamins in the metabolism of C1 units, as a biochemical interpretation of the relationships between vitamin B12 and biotin. 相似文献
16.
Takeo Deguchi MItsuo Saito Momoko Kono 《Biochimica et Biophysica Acta (BBA)/General Subjects》1978,544(1):8-19
Hydroxylamine and N-methylhydroxylamine prevented the activation of soluble guanylate cyclase by the endogenous activator as well as by nitroso compounds such as N-methyl-N′-nitro-N-nitroguanidine or nitroprusside, while the other derivaties of hydroxylamine were ineffective. Hydroxylamine and N-methylhydroxylamine did not alter the basal guanylate cyclase activity of purified enzyme preparations. Kinetics analysis indicated that N-methylhydroxylamine competes with N-methyl-N′nitro-N-nitrosuguanidine for guanylate cyclase. The activation of guanylate cyclase by N-methyl-N′-nitro-N-nitrosoguanidine and its inhibition by N-methylhydroxylamine were reversible reactions. These efects of N-methyl-N′-nitro-N-nitrosoguanine and N-methylhydroxylamine were observed with guanylate cyclase from other tissues.N-Methylhydroxylamine preveneed the increase of guanosine 3′,5′-monophosphate (cyclic GMP) levels in cerebellar slices of guinea pig by N-methyl-N′-nitro-N-nitroguanidine, veratridine and adenosine, while the elevalations of adenosine 3′,5′-monophosphate by these agents were not affected. N-Methylhyroxylamine also blocked the increased of cyclic GMP levels by carbachol, prostaglandin E1 and N-methyl-N′-nitro-N-nitrosoguanidine in neuroblastoma N1E 115 cells. Thus N-methylhydroxylamine prevents the activation of guanylate cyclase and the increased synthesis of cyclic GMP in responses to transmitters without blocking the synthesis of cyclic GMP via basal enzyme activity. 相似文献
17.
Two ribonuclease H activities have been purified from Saccharomyces cerevisiae. The major protein, RNase HA is an acidic protein with a molecular weight of 65,000. RNase HB is a basic protein with molecular weight of 54,000. Both RNases are active at alkaline pH range and require divalent cations for activity. RNase HA has an absolute requirement for Mg2+, while Mn2+ can replace Mg2+ for RNase HB. RNase HA is inhibited by low concentrations of N-ethylmaleimide, whereas RNase HB activity is unaffected under similar conditions. Substrate specificity studies using various polyribonucleotide · poly-deoxynucleotide hybrids showed that RNase HA preferentially degrades polycytidylate, while RNase HB is specific for polyadenylate. Kinetic analysis of the degradation of specifically end-labeled polymers and analysis of the products of the two yeast RNase H enzymes showed that yeast RNase HA is an endonuclease producing 5′-phosphorylated oligonucleotides while yeast RNase HB is a 5′-exonuclease producing 5′-AMP. 相似文献
18.
The metabolism of S-methyl-l-cysteine 总被引:1,自引:1,他引:0
1. Methylsulphinylacetic acid, 2-hydroxy-3-methylsulphinylpropionic acid and methylmercapturic acid sulphoxide (N-acetyl-S-methyl-l-cysteine S-oxide) were isolated as their dicyclohexylammonium salts from the urine of rats after they had been dosed with S-methyl-l-cysteine. 2. A fourth sulphoxide was isolated but not identified. 3. The excretion of sulphate in the urine of rats dosed with S-methyl-l-cysteine was measured. 4. The metabolism of S-methyl-l-cysteine by the hamster and guinea pig was examined chromatographically. 5. The preparation of the following compounds is reported: (−)-dicyclohexylammonium methyl-mercapturate sulphoxide; the dicyclohexylammonium salts of the optically inactive forms of 2-hydroxy-3-methylthiopropionic acid, 2-hydroxy-3-methyl-sulphinylpropionic acid and methylsulphinylacetic acid. 相似文献
19.
This study was conducted to assess effects of harvest date (i.e., 40 and 60 d after planting) and N fertilization rate (i.e., 120, 180, 240 kg N/ha) on the nutritive value of amaranth forage (Amaranthus hypochondriacus) using a factorial experiment with a randomized complete block design. The content of dry matter (DM), crude protein (CP), true protein (TP), ether extract (EE), water soluble carbohydrates (WSC), ash-free neutral detergent fiber (NDFom), ash-free acid detergent fiber (ADFom), lignin(sa), ash, Ca, P, Na, K, oxalic acid and nitrate were determined. Soluble CP (SP) and protein fractions non-protein N (A), true protein rapidly degraded in the rumen (B1), true protein degraded in the rumen at a moderate rate (B2), true protein associated with the cell wall and slowly degraded in the rumen (B3) and acid detergent insoluble CP (C) were measured according to the Cornell Net Carbohydrate and Protein System. In vitro gas production (IVGP), OM disappearance (OMD) and NDFom disappearance (NDFD) were determined using a gas production technique. Results showed that the later harvest date increased (P<0.05) DM, EE, WSC, NDFom, ADFom, lignin(sa), B3 and C; while CP, TP, ash, Ca, P, K, SP, A, B1, B2, nitrate, total and soluble oxalic acid, IVGP, b (i.e., gas production from the insoluble fermentable fractions at 120 h), c (i.e., rate of gas production during incubation), OMD and NDFD decreased (P<0.05). With increasing N fertilization rate, CP, TP, EE, P, nitrate, oxalic acid, SP, A, b, OMD and NDFD increased (P<0.05), however B2 declined (P<0.05). Increasing N fertilization increased yield, CP concentration and nutrient digestibility. At 40 d after planting use of amaranth forage as a ruminant feed is limited due to its high nitrate content. However, at 60 d, although a depression in digestibility and CP content occurred, this forage has the potential as a ruminant feed due to the much lower nitrate levels. 相似文献
20.
Electron paramagnetic resonance (epr) studies demonstrate that at low levels of conalbumin (CA) saturation with Fe3+ or VO2+, a ph-dependent preference of the metal exists for different protein binding-site configurations,A, B, and C. The vanadyl ion epr spectra of mixed VO2+, Fe3+-conalbumin in which Fe3+ is preferentially bound to the N- or C-terminal binding site are consistent with all three configurations being formed at both metal sites. At high pH the spectra suggest interaction between binding sites. In the absence of HCO3?, VO2+ is bound almost exclusively in B configuration; a full binding capacity of 2 VO2+ per CA is retained. Stoichiometric amounts of HCO3? convert the epr spectrum from B to an A, B, C type. Addition of oxalate to bicarbonate-free preparations converts the B spectrum to an A′, B, C′ type where the B resonances have lost intensity to the A′ and C′ resonances but have not changed position. The data suggest that configuration B is anion independent and that only one equivalent of binding sites at pH 9 responds to the presence of HCO31? or oxalate by changing configuration but not metal binding capability. The form of the bound anion may be HCO3? rather than CO32?. The formation rate of the colored ferric conalbumin complex by oxidizing Fe2+ to Fe3+ in limited HCO3? at pH 9 is also consistent with one equivalent of sites having different anion requirements than the remaining sites. Increased NaCl or NaClO4 concentration or substitution of D2O for water as solvent affect the environment of bound VO2+, but the mechanisms of action are unknown. 相似文献