Detection of exocyclic guanine adducts in hydrolysates of hepatic DNA of rats treated with N-nitrosopyrrolidine and in calf thymus DNA reacted with alpha-acetoxy-N-nitrosopyrrolidine

This report describes the isolation and characterization of DNA adducts formed in vitro from alpha-acetoxy-N-nitrosopyrrolidine and in rats treated with the hepatocarcinogen N-nitrosopyrrolidine. Esterase-catalyzed hydrolysis of alpha-acetoxy-N-nitrosopyrrolidine in the presence of calf thymus DNA, followed by neutral thermal hydrolysis of the DNA, resulted in formation of three previously unknown Adducts 1-3. They were isolated and characterized by their UV, mass, and proton magnetic resonance spectra as the exocyclic 7,8-guanine adducts 2-amino-6,7,8,9-tetrahydro-9-hydroxypyrido[2,1-f]purine-4(3H)-one (Adduct 1), and cis- and trans-2-amino-7,8-dihydro-8-hydroxy-6-methyl-3H-pyrrolo[2,1-f] purine-4(6H)-one (Adducts 2 and 3). Adduct 1 was formed by addition of 4-oxobutyl diazohydroxide, or a related carbonium ion, to the 7 and 8 positions of guanine. Adducts 2 and 3 resulted from Michael addition of 2-butenal to the 7 and 8 positions of guanine. Esterase-catalyzed hydrolysis of alpha-acetoxy-N-nitrosopyrrolidine in the presence of DNA also produced the exocyclic 1,N2-propanodeoxyguanosine Adducts 4a and 4b which we have previously described. Neutral thermal hydrolysates of hepatic DNA isolated from rats treated with N-nitrosopyrrolidine contained a fluorescent adduct, as previously reported (E.J. Hunt and R.C. Shank, Biochem. Biophys. Res. Commun., 104: 1343, 1982). This fluorescent adduct was shown to be identical to Adduct 1. Adducts 2, 3, 4a, and 4b were not detected in hepatic DNA hydrolysates from these animals. The results of this study provide the first example of a structurally characterized DNA adduct formed in vivo from a cyclic nitrosamine and support the alpha-hydroxylation hypothesis of cyclic nitrosamine metabolic activation.

[The Balint syndrome]

This paper reports a case of complete form of Bálint syndrome. A 56-year-old male suffered form psychic paralysis of gaze, impaired visual attention and optic ataxia of sudden onset in the basis of sequlae of cerebral vascular disease. CT scans of the present case demonstrated low densities in the left frontal, parietal lobe and right basal ganglia, right parito-occipital lobe. As for possible anatomical substrate of the Balint syndrome. according to Damasio's atlas, the authors inferred that despit the multiplicity of lesions in the present case, prefrontal area, lobulus paritalis inferior gyrus angularis and the associated fibers between the prefrontal area and 18, 19 area of occipital lobe were considered to be most responsible for the production of the Balint syndrome.

Human kallistatin, a new tissue kallikrein-binding protein: purification and characterization

A new and specific tissue kallikrein-binding protein was identified in mammalian serum and in secreted transformed-cell culture media (Chao et al., Biochem. J. 239: 325-331, 1986). We have designated this kallikrein-binding protein as "kallistatin". Human kallistatin has been purified from serum, using chromatographic steps including DEAE-Sephadex, hydroxylapatite, Cibacron blue-Sepharose, Sephacryl S200, and preparative polyacrylamide gel electrophoresis. The purified kallistatin consists of a single polypeptide chain with an apparent molecular weight of approximately 54 kDa and isoelectric point of approximately 5.0. Kallistatin was eluted as a single peak on reverse-phase HPLC. The purified kallistatin and 125I-labelled human tissue kallikrein form a approximately a 92 kDa SDS- and heat-stable complex. The complex formation is pH dependent and is inhibited by 0.1% (W/V) of deoxycholate or SDS but not by 0.5% (W/V) of Triton X-100, digitonin, Lubrol or CHAPS. A approximately 54 kDa protein was identified in partially purified kallistatin by polyclonal anti-kallistatin antibodies in Western blot analysis and by its binding to 125I-labelled-human tissue kallikrein in ligand blotting. The role of kallistatin in regulating tissue kallikrein activity and metabolism may now be evaluated.

The role of expectancy in comparative judgments

Researchers interested in the processing of relational information have sought a satisfactory explanation for the congruity effect in linear orders. It is relatively easy to select either the greater of two objects that are high on a dimension or the lesser of two objects that are low on a dimension, but it is relatively difficult to determine the greater of two objects that are low in magnitude or the lesser of two objects that are high in magnitude. One explanation of the congruity effect is the expectancy hypothesis that claims that the choice of the comparative primes objects of particular magnitudes. We present two experiments that demonstrate that a congruity effect of equivalent magnitude is obtained when the comparative is presented after the stimulus pair. Moreover, this equivalence cannot be attributed to the salience of the dimensions we employed, because this equivalence held for stimuli that were classified as salient and for those classified as nonsalient. These findings are interpreted in the context of some current explanations of the congruity effect.

Radiation inactivation analysis of chloroplast CF0-CF1 ATPase

Radiation inactivation technique was employed to measure the functional size of adenosine triphosphatase of spinach chloroplasts. The functional size for acid-base-induced ATP synthesis was 450 +/- 24 kilodaltons; for phenazine methosulfate-mediated ATP synthesis, 613 +/- 33 kilodaltons; and for methanol-activated ATP hydrolysis, 280 +/- 14 kilodaltons. The difference (170 +/- 57 kilodaltons) between 450 +/- 24 and 280 +/- 14 kilodaltons is explained to be the molecular mass of proton channel (coupling factor 0) across the thylakoid membrane. Our data suggest that the stoichiometry of subunits I, II, and III of coupling factor 0 is 1:2:15. Ca2+- and Mg2+-ATPase activated by methanol, heat, and trypsin digestion have a similar functional size. However, anions such as SO3(2-) and CO3(2-) increased the molecular mass for both ATPase's (except trypsin-activated Mg2+-ATPase) by 12-30%. Soluble coupling factor 1 has a larger target size than that of membrane-bound. This is interpreted as the cold effect during irradiation.

Identification of crotonaldehyde as a hepatic microsomal metabolite formed by alpha-hydroxylation of the carcinogen N-nitrosopyrrolidine

Crotonaldehyde (2-butenal), which reacts with DNA and is mutagenic and carcinogenic, was identified as a hepatic microsomal metabolite of the hepatocarcinogen N-nitrosopyrrolidine. Incubation mixtures of N-nitrosopyrrolidine, cofactors, and hepatic microsomes from Aroclor pretreated or control F344 rats were derivatized with (2,4-dinitrophenyl)hydrazine reagent and the resulting mixtures analyzed by high-performance liquid chromatography. Crotonaldehyde (2,4-dinitrophenyl)hydrazone was identified by its retention time in two different systems and by its ultraviolet and mass spectrum. The ratio of 4-hydroxybutyraldehyde, which has previously been identified as a metabolite of NPYR, to crotonaldehyde was 1.5-2 over a range of substrate concentrations. The approximate values of Km and nu max for crotonaldehyde were 5.8 mM and 0.6 nmol/min/mg of protein and for 4-hydroxybutyraldehyde 14.1 mM and 1.7 nmol/min/mg of protein, for substrate concentrations between 1 and 8 mM, with microsomes from Aroclor pretreated rats. The ratio of 4-hydroxybutyraldehyde to crotonaldehyde was 1.9 upon esterase-catalyzed solvolysis of alpha-acetoxy-N-nitrosopyrrolidine, a stable precursor to the initial product of N-nitrosopyrrolidine alpha-hydroxylation. These results demonstrate that crotonaldehyde is formed upon metabolic alpha-hydroxylation of N-nitrosopyrrolidine and suggest that it may be involved in N-nitrosopyrrolidine-macromolecule interactions.

Functional size of photosynthetic electron transport chain determined by radiation inactivation

Radiation inactivation technique was employed to determine the functional size of photosynthetic electron transport chain of spinach chloroplasts. The functional size for photosystem I+II (H(2)O to methylviologen) was 623 +/- 37 kilodaltons; for photosystem II (H(2)O to dimethylquinone/ferricyanide), 174 +/- 11 kilodaltons; and for photosystem I (reduced diaminodurene to methylviologen), 190 +/- 11 kilodaltons. The difference between 364 +/- 22 (the sum of 174 +/- 11 and 190 +/- 11) kilodaltons and 623 +/- 37 kilodaltons is partially explained to be due to the presence of two molecules of cytochrome b(6)/f complex of 280 kilodaltons. The molecular mass for other partial reactions of photosynthetic electron flow, also measured by radiation inactivation, is reported. The molecular mass obtained by this technique is compared with that determined by other conventional biochemical methods. A working hypothesis for the composition, stoichiometry, and organization of polypeptides for photosynthetic electron transport chain is proposed.

Anti-progesterone monoclonal antibody affects early cleavage and implantation in the mouse by mechanisms that are influenced by genotype

Pregnancy was blocked by anti-progesterone monoclonal antibody in two inbred (BALB/cJ, CBA/Ca) but to a lesser degree in an F1 hybrid (CBA/Ca male X BALB/cJ female) or an outbred (Tuck's no. 1) stock of mice when antibody was injected intraperitoneally (i.p.) at 32 h post coitum (p.c.) using a dosage of 9.5-10.9 nmol. This different antifertility effect could not be explained solely by altered tubal transport in inbred mice since the rate of transport was slightly accelerated in one stock (BALB/c) but not in another (CBA). In crossbred mice tubal transport was not significantly altered by antibody treatment. At Day 3 (54-58 h p.c.), the majority of embryos in control mice were at the 4-cell and 8-cell to morula stages in inbred and crossbred stock, respectively, but after antibody treatment they were mainly at the 4-cell stage in all 4 stocks. At Day 4 (78-82 h p.c.) the majority of embryos in control females had reached the blastocyst stage in all stocks, whereas after antibody treatment they had reached this stage in crossbred stock and relatively few had progressed so far in inbred stock. The results indicate that there are two events in early gestation which are susceptible to passive immunization with anti-progesterone monoclonal antibody. The first of these occurs during cleavage shortly after the 4-cell stage when embryo development was arrested in two inbred stocks of mice. Antibody effects on cleavage were not direct since embryos cultured in the presence of high concentrations of antibody, or antibody saturated with progesterone, continued to develop in the normal way and formed blastocysts. The second event is the onset of implantation, an effect also influenced by genotype. The decidual cell reaction induced by intraluminal oil injection was blocked by antibody injected at 8 or 32 h p.c. in BALB/c females, but only when injected at 8 h, and not at 32 h p.c., in F1 hybrid females. The results show that there is a greater resistance in two crossbred stocks compared with two inbred stocks to the effects of passive immunization against progesterone in early pregnancy.

Identification of a new tissue-kallikrein-binding protein

We have identified a tissue-kallikrein-binding protein in human serum and in the serum-free culture media from human lung fibroblasts (WI-38) and rodent neuroblastoma X glioma hybrid cells (NG108-15). Purified and 125I-labelled tissue kallikrein and human serum form an approximately 92,000-Mr SDS-stable complex. The relative quantity of this complex-formation is measured by densitometric scanning of autoradiograms. Complex-formation between tissue kallikrein and the serum binding protein was time-dependent and detectable after 5 min incubation at 37 degrees C, with half-maximal binding at 28 min. Binding of 125I-kallikrein to kallikrein-binding protein is temperature-dependent and can be inhibited by heparin or excess unlabelled tissue kallikrein but not by plasma kallikrein, collagenase, thrombin, urokinase, alpha 1-antitrypsin or kininogens. The kallikrein-binding protein is acid- and heat-labile, as pretreatment of sera at pH 3.0 or at 60 degrees C for 30 min diminishes complex-formation. However, the formed complexes are stable to acid or 1 M-hydroxylamine treatment and can only be partially dissociated with 10 mM-NaOH. When kallikrein was inhibited by the active-site-labelling reagents phenylmethanesulphonyl fluoride or D-Phe-D-Phe-L-Arg-CH2Cl no complex-formation was observed. An endogenous approximately 92,000-Mr kallikrein-kallikrein-binding protein complex was isolated from normal human serum by using a human tissue kallikrein-agarose affinity column. These complexes were recognized by anti-(human tissue kallikrein) antibodies, but not by anti-alpha 1-antitrypsin serum, in Western-blot analyses. The results show that the kallikrein-binding protein is distinct from alpha 1-antitrypsin and is not identifiable with any of the well-characterized plasma proteinase inhibitors such as alpha 2-macroglobulin, inter-alpha-trypsin inhibitor, C1-inactivator or antithrombin III. The functional role of this kallikrein-binding protein and its impact on kallikrein activity or metabolism in vivo remain to be investigated.

Residual effect of storage in an elevated carbon dioxide atmosphere on the microbial flora of rock cod (Sebastes spp.)

A residual inhibitory effect on microbial growth due to modified-atmosphere (MA) storage (MA, 80% CO2-20% air) was demonstrated for rock cod fillets stored in MA and transferred to air at 4 degrees C. Results of measurements of CO2 concentrations of the fillets suggested that the residual effect after transfer from MA to air was not due to retention of CO2 at the surface of the fillets but was probably due to the microbial ecology of the system. Lactobacillus spp. and tan Alteromonas spp. (TAN) predominated after 7 and 14 days of storage in MA. During storage in MA, Pseudomonas spp. were inhibited or killed. Following transfer from MA to air, the percentage of the total flora represented by Lactobacillus spp. and TAN bacteria decreased, and 6 days after transfer Pseudomonas spp. were again dominant.

Anti-fertility effect of passive immunization against progesterone is influenced by genotype

The anti-fertility effect of a monoclonal progesterone antibody injected i.p. 32 h after mating is influenced by genotype since a single dose of 5.7 nmol immunoglobulin G successfully blocked the establishment of pregnancy in BALB/c but not in F1 hybrid mice (CBA male X BALB/c female). Progesterone concentrations in circulation were significantly higher at days 3 and 4 after mating in F1 females compared with those of the BALB/c stock. Moreover, the pattern of mitotic activity in the endometrium after passive immunization differed between the two genotypes. In treated BALB/c mice there was no increase in mitotic activity in stromal cells at days 3, 4 and 5 after mating (in contrast to BALB/c control females in which the number of stromal mitoses increased sharply). In F1 females there was a transient effect of antibody at day 3 (no increase in stromal mitoses but enhanced mitotic activity in the glandular epithelium compared with F1 control females), and subsequently a normal increase in mitotic divisions in stromal cells. The hypothesis is proposed that passive immunization against progesterone at 32 h after mating will only block the establishment of pregnancy in genotypes in which there is a gradual, rather than a steep rise in circulating progesterone concentrations during the preimplantation period. In F1 mice, high concentrations of circulating progesterone at days 3 and 4 of pregnancy apparently over-ride the effect of antibody and facilitate the normal development of stromal mitotic activity associated with the onset of implantation.

Bile acids. LXXVII. Large-scale preparation of 5 alpha-anhydrocyprinol from carp bile

An improved method of preparation of 5 alpha-anhydrocyprinol from large quantities of carp bile is reported. The following materials were obtained by this method: 5 alpha-anhydrocyprinol, 5 alpha-cholestane-3 alpha,7 alpha,12 alpha,25-tetrol, 5 alpha-cholestane 3 alpha,7 alpha,12 alpha,26-tetrol, an unidentified sterol from the neutral lipid fraction, allocholic acid and allochenodeoxycholic acid from the bile acid fraction. Yields of 5 alpha-anhydrocyprinol and bile acids vary in different batches. The identity and purity of these materials were verified by thin-layer chromatography, gas liquid chromatography and gas chromatography-mass spectrometry.

Effects of dietary indoles and isothiocyanates on N-nitrosodimethylamine and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone alpha-hydroxylation and DNA methylation in rat liver

Dietary-related indoles, isothiocyanates, and the allyl isothiocyanate glucosinolate, sinigrin, were administered to F344 rats in the diet for 2 weeks (chronic protocol) or by gavage 2 h before sacrifice (acute protocol) and the effects of these pretreatments on the alpha-hydroxylation of two carcinogenic nitrosamines, N-nitrosodimethylamine (NDMA) and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), were evaluated. alpha-Hydroxylation was measured in vitro by quantitation of formaldehyde formation upon incubation of the nitrosamines with liver microsomes, and in vivo by quantitation of levels of 7-methylguanine and O6-methylguanine in hepatic DNA, 4 h after nitrosamine treatment. Compounds shown to be inhibitory in the in vitro assay were selected to be further evaluated using the in vivo assay. The results of the in vitro assays showed that indoles were inducers of the demethylation of both nitrosamines. Indole, L-tryptophan and indole-3-carbinol were strong inducers of NDMA and NNK demethylation, respectively. In contrast, isothiocyanates such as phenethyl isothiocyanate and phenyl isothiocyanate demonstrated a wide range of inhibitory activities toward demethylation of these nitrosamines in both the acute and chronic studies. Chronic, but not acute, pretreatment with sinigrin also caused a significant decrease in the demethylation of NDMA and NNK. In view of their promising inhibitory activities, the effects of phenethyl isothiocyanate, phenyl isothiocyanate and sinigrin on the in vivo methylation of DNA by NDMA and NNK were evaluated. The results were parallel to those obtained in the in vitro assays. Phenethyl isothiocyanate, phenyl isothiocyanate and sinigrin generally inhibited the formation of 7-methylguanine and O6-methylguanine in rat hepatic DNA. The results of this study suggest that these compounds could be anticarcinogenic to NDMA and NNK.

Beta- to omega-hydroxylation of the esophageal carcinogen methyl-n-amylnitrosamine by the rat esophagus and related tissues

When the esophageal carcinogen methyl-n-amylnitrosamine (MNAN; concentration, 3 mg/liter) was incubated in vitro with rat esophagi for 3 hr, five principal neutral metabolites (Metabolites 2 to 6; total yield, 3.0% of the MNAN per 100 mg tissue) were separated by gas chromatography, with detection by a thermal energy analyzer. Rat liver produced similar metabolites (total yield, 2.1% of the MNAN per 100 mg tissue). Metabolites 4 to 6 and a minor product, Metabolite 7, were tentatively identified as 2-, 3-, 4-, and 5-hydroxy-MNAN (HO-MNAN), respectively, from a comparison of their gas chromatography retention times with those of the synthesized compounds. Rat esophagus produced similar amounts of 3- and 4-HO-MNAN and lesser amounts of 2-HO-MNAN, whereas rat liver produced mainly 4-HO-MNAN. Rat nasal tissue metabolized 8.0% of the MNAN per 100 mg tissue, with a metabolite pattern like that of the esophagus. Rat lungs produced mostly 5-HO-MNAN. A comparison of yields from tissues of rats, hamsters, guinea pigs, and mice supported the view that the total production of neutral MNAN metabolites indicated the sensitivity of MNAN carcinogenesis, with some exceptions. MNAN injected i.p. was less carcinogenic for the esophagus and nasal cavity in Sprague-Dawley than in MRC-Wistar rats, perhaps because the livers of Sprague-Dawley rats metabolized more of the MNAN. The urine of MNAN-treated MRC-Wistar rats contained MNAN and metabolites provisionally identified as 2-, 3-, and (as the major product) 4-HO-MNAN. The identity of the urinary 4-HO-MNAN was confirmed by gas chromatography-mass spectrometry. We speculate that tissues like the esophagus, which (unlike the liver) produce significant proportions of 2- and 3-HO-MNAN, also produce significant amounts of the most likely proximal carcinogen, 1-HO-MNAN.

Structure-function studies on the bradykinin potentiating peptide from Chinese snake venom (Agkistrodon halys Pallas)

A bradykinin potentiating peptide (BPP) was purified from the Chinese snake venom (Agkistrodon halys Pallas). The amino acid sequence of this BPP was determined to be pyroGlu-Gly-Arg-Pro-Pro-Gly-Pro-Pro-Ile-Pro-Pro. Removal of the N-terminal residue with pyroglutamate aminopeptidase enhanced two-fold the activity of BPP, the resulting despyroGlu-BPP gradually lost its activity on further Edman degradation. However, around 90% of the original activity was still present in the C-terminal tripeptide Ile-Pro-Pro. Some analogs of this tripeptide were synthesized by the conventional method, and investigated by two biological assays, i.e., potentiating response on bradykinin (BK) and inhibitory activity on angiotensin converting enzyme (ACE). It was shown that the two biological activities inherent in the synthetic analogs were not parallel to each other. In addition, the isolated guinea pig ileum strips treated with chelating agent to irreversibly inactivate kininase (the same enzyme ACE) still responded to BPP. Consequently the potentiating effect of BPP on BK in vitro bioassay might be due to its influence on the binding receptor for BK rather than the inhibitory effect on kininase.

Extraction of proteins for sodium dodecyl sulfate-polyacrylamide gel electrophoresis from protease-rich plant tissues

A method of extracting proteins for sodium dodecyl sulfate-polyacrylamide gel electrophoresis from plant tissues with high protease activity was described. It resolved protein bands in high-molecular-weight regions of the gel and replaced commonly used procedures which showed severe degradation of proteins, even in the presence of protease inhibitors.

Action of anti-progesterone monoclonal antibody in blocking pregnancy after postcoital administration in mice

Anti-progesterone monoclonal antibody injected intraperitoneally as a single dose 32 h post coitum completely blocked pregnancy in BALB/c and CBA nulliparous mice. The dose required was greater in CBA than in BALB/c females, but in both strains no implantation sites were detectable at autopsy on day 10 after mating. The action of the antibody in BALB/c females was associated with a failure to initiate an implantation response as indicated by the Pontamine Blue reaction. The most pronounced effect, however, was an arrest of embryonic development at a stage prior to cavitation. Plasma progesterone concentration in blood taken by cardiac puncture was greatly increased after treatment, by virtue of high-affinity binding by antibody in circulation. The results show that passive immunization against progesterone shortly after mating interferes with early hormone-dependent steps which are essential for normal embryonic development.

Studies on bradykinin potentiating peptide (BPP) from venom of Zhejiang pit viper (Agkistrodon halys pallas)--relationship between structure and function of BPP

The structure of the bradykinin potentiating peptide component BPP1 from a 70% methanol extract of the lyophilized powder of pit viper from Zhejiang Province is shown as follows: (formula see text) When the pyroglutamyl residue was removed by pyroglutamate aminopeptidase, the activity of BPP1 was enhanced two-fold but decreased gradually during the course of Edman degradation. The above facts show that the structure integrity of the C-terminal is absolutely necessary for the activity of BPP1.

Quantitative analysis of Roussin red methyl ester in pickled vegetables

In a study of the etiological factors in esophageal cancer, Roussin red methyl ester was isolated and identified in pickled vegetables of Linxian County, North China, where there is a high incidence of esophageal cancer. In this paper, a method is described for quantitative analysis of Roussin red methyl ester in pickled vegetables by gas chromatography-high-resolution mass spectrometry single-ion monitoring. The content of Roussin red methyl ester in pickled vegetables from Linxian has been found to be 0.1 to 4.5 mg/kg, and that from Beijing is below 0.005 mg/kg, which is the detection limit of the analytical method used. The marked difference between the contents might be one of the possible reasons for the difference in esophageal cancer incidence between the two regions.

Cobalt-substituted cytochrome P-450cam

Reconstitution of the apo-cytochrome with cobalt protoporphyrin provides a faithful P-450cam analogue as characterized by optical, ligand-binding, and enzymatic parameters. The thiol and cyanide complexes exhibit Soret "hyper" spectra, not previously observed in cobalt porphyrins. Substrate-induced spectral changes and limited stereospecific hydroxylation activity are retained in the cobalt P-450cam. The EPR (electron paramagnetic resonance) spectra of the reduced cobaltous protein indicate clearly an endogenous axial ligand other than a nitrogenous base and support an assignment of thiolate coordination. A thiolate ligand is also indicated by EPR measurements in the oxygenated cobaltous analogue. By analogy, these studies suggest that the native ferrous and oxygenated P-450cam states retain a thiolate axial ligand.

Mutagenic, transforming and promoting effect of pickled vegetables from Linxian county, China

A recent epidemiological survey in China showed that there is a regional distribution of esophageal cancer and a correlation between mortality for this cancer and environmental factors, especially the consumption of pickled vegetables. A series of experimental studies with pickled vegetable extract were done using different in vitro biological systems. The results showed that pickled vegetable extract induced 6-thioguanine-resistant mutants in V79 cells and increased sister chromatid exchanges in the same cells and in Syrian hamster embryo cells. Pickled vegetables extract induced transformed foci in Syrian hamster embryo cells and in 3-methylcholanthrene initiated C3H/10T1/2 cells. The mutagenic, transforming and promoting activities of pickled vegetable extract seen in vitro conform with in vivo results and provide evidence for the presence of a mutagen and/or a carcinogen in pickled vegetable extract. A possible role of pickled vegetables consumption in the etiology of esophageal cancer is discussed.

Resonance Raman and EPR of nitrosyl human hemoglobin and chains, carp hemoglobin, and model compounds. Implications for the nitrosyl heme coordination state

We report the joint resonance Raman (RR) and electron paramagnetic resonance (epr) study of five- and six-coordinate nitrosyl heme model compounds and of the titled nitrosyl hemoproteins. Both epr and RR spectra fall into two types which, in the models, correspond to five- and six-coordinate nitrosyl hemes. However, neither RR nor epr spectroscopy is highly sensitive to the nature of the bond between a nitrosyl heme and a coordinated nitrogenous base, nor do the results of one technique uniformly correlate with those of the other. It is not possible to use epr spectroscopy as a test for the coordination state of a nitrosyl heme. The position of the highest frequency (depolarized) RR band possibly provides such a test. Any breaking of the very weak bond between nitrosyl heme and proximal histidine in T state human HbNO is more a consequence of tertiary structural features unique to the human alphaNO chains than it is of properties of the T quaternary conformation.

Cobalt-substituted horseradish peroxidase

Horseradish peroxidase can be reconstituted with cobalt porphyrin to give a cobaltic holoenzyme having physicochemical properties quite similar to those of the native ferric protein. The cobaltic protein (Co3+HRP) can be reduced to the cobaltous form (CoHRP), the analogue of ferroperoxidase and the reduced cobalt protein can bind O2 to form an analogue of oxyferroperoxidase (Compound III). Since both the CoHRP and oxy-CoHRP are EPR-visible, the cobalt has been used to probe the nature of the heme crevice in these two protein forms. The occurrence of a three-line 14N superhyperfine pattern in the spectrum of the former unambiguously shows that in the divalent state of the protein the proximal axial ligand is a nitrogenous base. The spectrum of the latter shows a uniquely large Aparallel(59Co) = 23.2 G. Although we confirm the reported failure of the Co3+HRP to catalyze peroxide-dependent oxidations of classical peroxidase substrates (Gjessing, E.C., and Sumner, J.B. (1942) Arch. Biochem. 1, 1), the oxy-CoHRP does undergo oxidation-reduction reactions analogous to those exhibited in the cytochrome P-450 catalytic cycle.