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Background/objectives Studies of the effect of vitamin B12 and folate on the risk of asthma and hay fever have shown inconsistent results that may be biased by reverse causation and confounding. We used a Mendelian randomization approach to examine a potential causal effect of vitamin B12 and folate on hay fever, asthma, and selected biomarkers of allergy by using 11 vitamin B12-associated single-nucleotide polymorphisms (SNPs) and 2 folate-associated SNPs as unconfounded markers. Subjects/methods We included 162,736 participants from 9 population-based studies including the UK Biobank. Results were combined in instrumental variable and meta-analyses and effects expressed as odds ratios (ORs) or estimates with 95% confidence interval (CI). Results Using genetic proxies for B12 and folate, instrumental variable analyses did not show evidence for associations between serum B12 and hay fever: OR = 1.02 (95% CI: 0.98, 1.05), asthma: OR = 0.99 (95% CI: 0.95, 1.04), allergic sensitization: OR = 1.02 (95% CI: 0.74, 1.40), or change in serum IgE: 10.0% (95% CI: -9.6%, 29.6%) per 100 pg/ml B12. Similarly, there was no evidence for association between serum folate and hay fever: OR = 0.74 (95% CI: 0.45, 1.21), asthma: OR = 0.80 (95% CI: 0.43, 1.49), or allergic sensitization: OR = 1.92 (95% CI: 0.11, 33.45), but there was a statistically significant association with change in serum IgE: 2.0% (95% CI: 0.43%, 3.58%) per 0.1 ng/ml serum folate. Conclusions Our results did not support the hypothesis that levels of vitamin B12 and folate are causally related to hay fever, asthma, or biomarkers of allergy, but we found evidence of a positive association between serum folate and serum total IgE., Author(s): Tea Skaaby [sup.1] , Amy E. Taylor [sup.2] [sup.3] , Rikke K. Jacobsen [sup.1] , Line T. Møllehave [sup.1] , Nele Friedrich [sup.1] [sup.4] , Betina H. Thuesen [sup.1] [...]

The present project aimed to estimate bioavailability of dietary vitamin B12, for which little information is available in growing pigs. Two approaches, each using 2 quantities of dietary cyanocobalamin, were compared; the first was based on whole body retention for 8 d and the second was based on nycthemeral portal net flux of vitamin [B.sub.12]. In the first trial, 15 blocks of 3 pigs (31.7 [+ or -] 0.5 kg of BW) were formed according to their vitamin [B.sub.12] status. Within each block, 1 pig (CONT) was killed and tissues were sampled for vitamin [B.sub.12] determination. The remaining 2 piglets were fed 25 ([B.sub.12]-25) or 250 ([B.sub.12]-250) [micro]g daily of cyanocobalamin for 8 d. Urine was sampled twice daily, and the pigs were killed and sampled as CONT pigs. The total content of vitamin [B.sub.12] in the carcass, urine, and intestinal tract was affected by the dietary treatments (P < 0.01) but not in the liver (P > 0.019). The whole body retention of vitamin B12 was greater (P = 0.02) in [B.sub.12]-250 than [B.sub.12]-25 pigs, but the corresponding bioavailability was estimated to be 5.3 and 38.2%, respectively. In trial 2, 11 pigs (35.1 [+ or -] 4.0 kg of BW and 75.4 [+ or -] 5.9 d of age) fed a diet unsupplemented with vitamin [B.sub.12] from weaning at 28 d of age were surgically equipped with catheters in the portal vein and carotid artery and an ultrasonic flow probe around the portal vein. Each pig received 3 boluses of 0 ([B.sub.12]-0), 25, and 250 [micro]g of dietary vitamin [B.sub.12] according to a crossover design. Postprandial nycthemeral arterial plasma concentrations of vitamin [B.sub.12] reached minimum values (P < 0.01) between 15 and 18 h postmeal that were 29.6, 15.6, and 10.0% less than the premeal values for [B.sub.12]-0, [B.sub.12]-25, and [B.sub.12]-250 pigs, respectively (linear, P < 0.01). The cumulative net flux of vitamin [B.sub.12] for 24 h corresponded to 2.4 and 5.1 [micro]g for [B.sub.12]-25 and [B.sub.12]-250 treatments, respectively, and the corresponding bioavailability was estimated to be 9.7 and 2.0%, respectively. Although bioavailability estimates varied according to approaches, both showed the inverse relationship between dietary vitamin [B.sub.12] and bioavailability of the vitamin. The dietary supplement of 25 [micro]g was sufficient to maximize hepatic vitamin [B.sub.12] retention and to attenuate the nycthemeral decrease of arterial plasma concentration of the vitamin. Key words: cyanocobalamin, intestinal absorption, pig, retention, vitamin [B.sub.12] doi: 10.2527/jas.2010-2979

Background/Objectives: Methionine synthase catalyzes the conversion of 5- methyltetrahydrofolate to tetrahydrofolate and homocysteine (Hcy) to methionine using vitamin [B.sub.12] as a cofactor. Transcobalamin is the main transporter of vitamin [B.sub.12] from blood into cells. This study was undertaken to assess the relationship between the transcobalamin P259R (TCN2 776C>G) polymorphism and both serum vitamin [B.sub.12] and total Hcy (tHcy) levels. Subjects/Methods: The population comprised 613 men from Northern Ireland, aged 30-49 years, for whom tHcy, serum vitamin [B.sub.12] and serum folate concentrations were available. TCN2 776C>G genotypes were determined using a TaqMan 5' nuclease Real-Time PCR assay. Standard statistical tests of association were applied to assess the relationships between the polymorphism and phenotypic variables. Results: The TCN2 776CC homozygous genotype was associated with lower serum vitamin [B.sub.12] concentrations compared with the 776CG ([P.sub.unadjusted] = 0.01; [P.sub.adjusted] = 0.03) and 776GG genotypes ([P.sub.unadjusted] = 0.015; [P.sub.adjusted] = 0.045). Among individuals with vitamin [B.sub.12] concentrations in the lower half of the distribution, tHcy concentrations were higher in TCN2 776GG homozygotes than in individuals with the other genotypes ([P.sub.unadjusted] = 0.015; [P.sub.adjusted] = 0.06). Conclusions: These data suggest that, relative to transcobalamin with arginine at position 259 (776G), transcobalamin with proline at this position (776C) is either more efficient at vitamin [B.sub.12] transport from blood to tissues or has higher affinity for vitamin [B.sub.12]. Furthermore, vitamin [B.sub.12] status influences the relationship between TCN2 776C>G genotype and tHcy concentrations. Thus, the TCN2 776C> G polymorphism may contribute to the risk of pathologies associated with a low [B.sub.12], and high tHcy phenotype. European journal of Clinical Nutrition (2010) 64, 1338-1343; doi:10.1038/ejcn.2010.157; published online 1 September 2010 Keywords: cobalamin; Hcy; transcobalamin; vitamin [B.sub.12], Introduction Vitamin [B.sub.12] (cobalamin) is an enzyme cofactor that is synthesized only in microorganisms and, in humans, must be obtained from food or supplements (Scott and Weir, 1994). Serum vitamin [...]

Axenic cultures of the [N.sub.2]-fixing marine cyanobacterium Crocosphaera watsonii exhibit very high [B.sub.12] excretion rates (up to 40 times higher per cell), compared to the smaller non--[N.sub.2]-fixing strain of marine Synechococcus. The effect of N availability on vitamin synthesis is also evident in the non-diazotrophic strain, as they release five times more [B.sub.12] under N-replete conditions relative to N-limiting conditions, although this value is still an order of magnitude smaller than the amount produced by the diazotroph. The cyanobacterial contribution to the oceanic B12 supply may be ~ 50 times higher than the contribution of heterotrophic bacteria. Oceanic cyanobacteria do not compete for exogenous [B.sub.12] with other prokaryotes and eukaryotes, but instead are obligate producers, thereby defining a unique dual ecological role for [N.sub.2]-fixing cyanobacteria in the oligotrophic ocean. They provide both a source of 'new' bioavailable nitrogen and the [B.sub.12] needed to support the growth of larger auxotrophic eukaryotic phytoplankton important for the biological carbon pump. doi: 10.4319/lo.2010.55.4,1959

A strictly host-dependent lifestyle has profound evolutionary consequences for bacterial genomes. Most prominent is a sometimes-dramatic amount of gene loss and genome reduction. Recently, highly reduced genomes from the co-resident intracellular symbionts of sharpshooters were shown to exhibit a striking level of metabolic interdependence. One symbiont, called Sulcia muelleri (Bacteroidetes), can produce eight of the 10 essential amino acids, despite having a genome of only 245 kb. The other, Baumannia cicadellinicola ([gamma]-Proteobacteria), can produce the remaining two essential amino acids as well as many vitamins. Cicadas also contain the symbiont Sulcia, but lack Baumannia and instead contain the co-resident symbiont Hodgkinia cicadicola ([alpha]-Proteobacteria). Here we report that, despite at least 200 million years of divergence, the two Sulcia genomes have nearly identical gene content and gene order. Additionally, we show that despite being phyiogenetically distant and drastically different in genome size and architecture, Hodgkinia and Baumannia have converged on gene sets conferring similar capabilities for essential amino acid biosynthesis, in both cases precisely complementary to the pathways conserved in Sulcia. In contrast, they have completely divergent capabilities for vitamin biosynthesis. Despite having the smallest gene set known in bacteria, Hodgkinia devotes at least 7% of its proteome to cobalamin (vitamin [B.sub.12]) biosynthesis, a significant metabolic burden. The presence of these genes can be explained by Hodgkinia's retention of the cobalamin-dependent version of methionine synthase instead of the cobalamin-independent version found in Baumannia, a situation that necessitates retention of cobalamin biosynthetic capabilities to make the essential amino acid methionine. cobalamin | genome reduction | genome sequencing | proteomics

Byline: Sidharth. Sonthalia, Adity. Priya, Desmond. Tobin Background: The incidence of self-reported premature hair graying (PHG) seems to be on the rise. PHG has a profound impact on the patient's [...]

Background/Objectives: The roles of vitamin B[sub.12] and homocysteine concentration in depression are not clear. We investigated cross-sectional and prospective associations of serum vitamin B[sub.12] and plasma homocysteine with depressive symptoms in Dutch older adults. Subjects/Methods: In the Longitudinal Aging Study Amsterdam (LASA), blood was collected in 1995/1996 among 1352 men and women aged [succeeds/equal to]65 years. Depressive symptoms were assessed with the Center for Epidemiologic Studies Depression Scale (CES-D) six times from 1995/1996 to 2011/2012. Multiple linear regression and mixed models were used to assess whether vitamin B[sub.12] and homocysteine were associated with severity at baseline and course of depressive symptoms over 16 years. Cox regression analyses were performed for the associations with incidence of depression (CES-D [succeeds/equal to]16 and/or antidepressant use). All analyses were adjusted for sociodemographic characteristics and lifestyle factors. Results: Vitamin B[sub.12] was neither cross-sectionally (n=1205) nor prospectively (n=1012) associated with depressive symptoms (adjusted [beta] for CES-D over time, lowest versus highest quartile: -0.04 (95% confidence interval (CI): -0.15-0.06)). We also found no association with incident depression (n=853), except for a higher risk of depression over time in younger participants (aged 64.8-73.4 years; continuous vitamin B12, adjusted hazard ratio per s.d.: 1.38 (95% CI: 1.10-1.72)). For homocysteine, no associations were found, except for a lower risk of depression in younger participants. Conclusions: Our study did not confirm earlier shown associations of serum vitamin B[sub.12] and plasma homocysteine with severity and course of depressive symptoms and incidence of depression in older adults. Further research into the influence of homocysteine metabolism on mental health is needed. European Journal of Clinical Nutrition (2017) 71, 468-475; doi: 10.1038/ejcn.2016.224; published online 1 February 2017, Author(s): L E M Elstgeest [1]; I A Brouwer [1]; B WJ H Penninx [2]; N M van Schoor [3]; M Visser [1, 4] Introduction A low vitamin B[sub.12] status, [...]

Study is conducted to find whether the well characterized ligand trans influence described for free cob(III)alamins applies to cob(III)alamins bound to methionine synthase (MetH). It is observed that affinity of flavodoxin for cob(III)alamin forms of MetH varied inversely with the ligand trans influence.

Abstract Nail health and appearance are global concerns. We investigated the use of biotin vitamin E, alpha-tocopherol, vitamin C (ascorbic acid), vitamin A, retinoids, retinol, retinal, silicon, zinc, iron, copper, [...]

Different corrinoids of different geometry are interacted with the transporting proteins HC, TC and IF. The absolute affinities for a group of analogues are determined and the critical kinetic steps important for the ligand recognition are found.

The growth of Dehalococcoides ethenogenes 195 is described in a defined mineral salts medium, improved growth of strain 195 when the medium is amended with high concentrations of vitamin [B.sub.12]. The growth of D. ethenogenes strain 195 in defined medium is optimized by providing high concentrations of vitamin [B.sub.12].

There is a need for an improved test of human ability to assimilate dietary vitamin [B.sub.12]. Assaying and understanding absorption and uptake of [B.sub.12] is important because defects can lead to hematological and neurological complications. Accelerator mass spectro metry is uniquely suited for assessing absorption and kinetics of carbon-14 ([sup.14]C)-Iabeled substances after oral ingestion because it is more sensitive than decay counting and can measure levels of [sup.14]C in microliter volumes of biological samples with negligible exposure of subjects to radioactivity. The test we describe employs amounts of [B.sub.12] in the range of normal dietary intake. The [B.sub.12] used was quantitatively labeled with [sup.14]C at one particular atom of the dimethylbenzimidazole (DMB) moiety by exploiting idiosyncrasies of Salmonella metabolism. To grow aerobically on ethanolamine,Salmonella enterica must be provided with either preformed [B.sub.12] or two of its precursors, cobinamide and DMB. When provided with [sup.14]C-DMB specifically labeled in the C2 position, cells produced [sup.14]C-[B.sub.12] of high specific activity (2.1 GBq/ mmol, 58 mCi/mmol) (1Ci = 37 GBq) and no detectable dilution of label from endogenous DMB synthesis. In a human kinetic study, a physiological dose (1.5[micro]g, 2.2 kBq/59 nCi) of purified [sup.14] C-B.sub.12] was administered and showed plasma appearance and clearance curves consistent with the predicted behavior of the pure vitamin. This method opens new avenues for study of [B.sub.12] assimilation. dimethylbenzimidazole | ethanolamine | metabolic engineering | Salmonella | Schilling test

An insight into a previously unknown step in [B.sub.12] biosynthesis was unexpectedly obtained through our analysis of a mutant of the symbiotic nitrogen fixing bacterium Sinorhizobium meliloti. This mutant was identified based on its unusually bright fluorescence on plates containing the succinoglycan binding dye calcofluor. The mutant contains a Tn5 insertion in a gene that has not been characterized previously in S. meliloti. The closest known homolog is the bluB gene of Rhodobacter capsulatus, which is implicated in the biosynthesis of [B.sub.12] (cobalamin). The S. meliloti bluB mutant is unable to grow in minimal media and fails to establish a symbiosis with alfalfa, and these defects can be rescued by the addition of vitamin [B.sub.12] (cyanocobalamin) or the lower ligand of cobalamin, 5,6-dimethylbenzimidazole (DMB). Biochemical analysis demonstrated that the bluB mutant does not produce cobalamin unless DMB is supplied. Sequence comparison suggests that BluB is a member of the NADH/flavin mononucleotide (FMN)-dependent nitroreductase family, and we propose that it is involved in the conversion of FMN to DMB. cobalamin | symbiosis | bacteria | vitamin [B.sub.12] | biosynthesis

Salmonella enterica degrades 1,2-propanediol (1,2-PD) by a pathway that requires coenzyme [B.sub.12] (adenosylcobalamin; AdoCbl). The genes specifically involved in 1,2-PD utilization (pdu) are found in a large contiguous cluster, the pdu locus. Earlier studies have indicated that this locus includes genes for the conversion of vitamin [B.sub.12] (cyanocobalamin; CNCbl) to AdoCbl and that the pduO gene encodes an ATP : cob(I)alamin adenosyltransferase which catalyses the terminal step of this process. Here, in vitro evidence is presented that the pduS gene encodes a bifunctional cobalamin reductase that catalyses two reductive steps needed for the conversion of CNCbl into AdoCbl. The PduS enzyme was produced in high levels in Escherichia coli. Enzyme assays showed that cell extracts from the PduS expression strain reduced cob(III)alamin (hydroxycobalamin) to cob(II)alamin at a rate of 91 nmol [min.sup.-1] [mg.sup.-1] and cob(II)alamin to cob(I)alamin at a rate of 7.8 nmol [min.sup.-1] [mg.sup.-1]. In contrast, control extracts had only 9.9 nmol [min.sup.-1] [mg.sup.-1] cob(III)alamin reductase activity and no detectable cob(II)alamin reductase activity. Thus, these results indicated that the PduS enzyme is a bifunctional cobalamin reductase. Enzyme assays also showed that the PduS enzyme reduced cob(II)alamin to cob(I)alamin for conversion into AdoCbl by purified PduO adenosyltransferase. Moreover, studies in which iodoacetate was used as a chemical trap for cob(I)alamin indicated that the PduS and PduO enzymes physically interact and that cob(I)alamin is sequestered during the conversion of cob(II)alamin to AdoCbl by these two enzymes. This is likely to be important physiologically, since cob(I)alamin is extremely reactive and would need to be protected from unproductive by-reactions. Lastly, bioinformatic analyses showed that the PduS enzyme is unrelated in amino acid sequence to enzymes of known function currently present in GenBank. Hence, results indicate that the PduS enzyme represents a new class of cobalamin reductase.

The colchicine-cobalamin bioconjugate exhibits nanomolar LC(sub 50) values against breast, brain, and melanoma cancer cell lines in culture. Attachment of colchicine and cobalamin is expected to increase the therapeutic index of the drug by limiting the side effects caused by the current nonselective administration of tubulin-targeted chemotherapeutic drugs.

Subclinical vitamin B-12 deficiency is common in the elderly. Encouraged by early indications, we investigated the plasma vitamin B-12 status in association with bone mineral content (BMC) and bone mineral density (BMD) in frail elderly people. Data of 194 free-living Dutch frail elderly (143 women and 51 men) were available. BMC and BMD were measured by dual energy X-ray analysis. Biochemical analyses were performed on plasma or serum including vitamin B-12, methylmalonic acid, homocysteine, 25-hydroxy vitamin D and parathyroid hormone. Women had higher plasma vitamin B-12 (288 and 238 pmol/L, respectively) and lower plasma homocysteine levels (15.8 and 21.3 [micro]mol/L, respectively) than men. Of the total explained variance of BMC and BMD in women (46 and 22%, respectively), 1.3-3.1% was explained by plasma vitamin B-12, in addition to weight and height or energy intake. In men, the variance of BMC and BMD was explained by weight, smoking and/or height (total [R.sup.2] was 53 and 25%, respectively), but not by plasma vitamin B-12. Osteoporosis occurred more often among women whose vitamin B-12 status was considered marginal or deficient than in women with a normal status, i.e., the prevalence odds ratios (after adjustment for weight, age and calcium intake) (95% confidence intervals) were 4.5 (0.8;24.8) and 6.9 (1.2;39.4), respectively. These results suggest that vitamin B-12 status is associated with bone health in elderly women. Future studies on bone health should take into account a possible role of vitamin B-12 status in different populations. KEY WORDS: * cobalamin * osteoporosis * multiple regression analysis * logistic analysis

Kinetic and mechanistic information on the reaction of nitric oxide with reduced form of aquacobalamin is studied. This contributes to the biological interactions observed between vitamin B12 and NO.

The characterization of the distance and relative orientation of the C5' methyl group of 5'-deoxyadenosine in vitamin B12 coenzyme-dependent ethanolamine deaminase is described.

Researchers examined the binding of cobalamin to methionine synthase by dividing the modular enzyme in half and then reacting one fragment with another fragment that contains the cobalamin factor. This enzyme methylates homocysteine using methyltetrahydrofolate as the methyl donor.

The existence of hyper-long axial Co(II) bonds in cobinamide B12 models is investigated using electron paramagnetic resonance spectroscopy.

A coenzyme B12 analogue with unusual properties is described.

A multinuclear solid-state NMR analysis of vitamin B12 was undertaken.

A product radical trap strategy is proposed to contribute to radical pair stabilization and productive reaction in ethanolamine deaminase.

Research is presented describing the interactions of aminoethanol-derived product radical catalytic intermediates and cryotrapped 2-aminopropanol-1-yl substrate radical with the active site of vitamin B12 coenzyme-dependent ethanolamine deaminase in disordered frozen aqueous solution.

Results points out to the involvement of cobK and cobJ genes in the anaerobic synthesis of cobalamin in Paracoccus denitrificans. This unusual anerobic behavior is mediated by the cobalamin-dependent ribonucleotide reductase.

Research was conducted to examine the mechanism of reactivation of diol dehydratase by its reactivating factor through the use of enzyme*cyanocobalamin complex as a model for inactivated holoenzyme. The intermediary formation of apoenzyme in the reactivating factor-mediated cobalamin exchanges and the role of ATP in the reactivation process are described. It is proposed that the reactivating factor is a new type of molecular chaperone that participates in reactivation of the inactivated enzymes.

Protein guidance of reactivity in the vitamin B12 coenzyme-dependent enzymes is characterized by the acceleration of the effective cobalt-carbon bond cleavage rate by approximately 10(to the 12th power)-fold relative to the rate for the free coenzyme in solution. This feature is attributed to substrate-derived radical formation and the specific interactions of the cobalamin moeity of the protein. Techniques of X-band electron spin-echo envelope modulation spectroscopy confirmed these protein-specific effects on cob(II)alamin structure and reactivity.

Receptors that endocytose high-density lipoproteins (HDL) have been elusive. Here yolk-sac endoderm-like cells were used to identify an endocytic receptor for HDL. The receptor was isolated by HDL affinity chromatography and identified as cubilin, the recently described endocytic receptor for intrinsic factor-vitamin [B.sub.12]. Cubilin antibodies inhibit HDL endocytosis by the endoderm-like cells and in mouse embryo yolk-sac endoderm, a prominent site of cubilin expression. Cubilin-mediated HDL endocytosis is inhibitable by [HDL.sub.2], [HDL.sub.3], apolipoprotein (apo)A-I, apoA-II, apoE, and RAP, but not by low-density lipoprotein (LDL), oxidized LDL, VLDL, apoC-I, apoC-III, or heparin. These findings, coupled with the fact that cubilin is expressed in kidney proximal tubules, suggest a role for this receptor in embryonic acquisition of maternal HDL and renal catabolism of filterable forms of HDL.

Research was conducted to determine the cellular component of the intestinal villus where transcobalamin II (TCII) is synthesized since the protein provides an important function in the intestinal absorption of vitamin B12. The TCII transcript was identified by the northern blot analysis of RNA from both proximal and distal small intestine. Results indicate that TCII is constitutively expressed in the intestinal villi where vascular endothelium is abundant.

Research was conducted to examine the hydrolytic dealkylation of organocobaloximes related to coenzyme B12. The organocobaloxime comples R-Co(DH)2(L) were prepared and characterized using 1H NMR and UV-vis spectroscopy. The Co-C bond hydrolysis rates were identified as a function of pH and temperature. An assessment and validation of the use of (coII(DH)2(OH2)2) as a radical trap in the kinetic determination of the Co-C bond dissociation enthalpy of coenzyme B12 was performed.

Catalytic films were produced through the covalent binding of vitamin B12 poly-L-lysine. The latter compound is covalently bound to graphite electrodes resulting in an ionic polymer coating that is stable in microemulsions. The films have reversible Co(II)/Co(I) voltammetry and were stable in microemulsion for four to five days. They can be used in the dehalogenation of various organohalides in water and microemulsions and for alkylation of activated olefins.

A study was conducted to analyze the coenzyme-B12-dependent rearrangement of 2-methyleneglutarate to (R)-3-methylitaconate catalyzed by 2-methyleneglutarate mutase. Ab initio molecular orbital theory was utilized to carry out the analysis. A transient fragmentation of the substrate after recombination of the fragments was examined. Results indicated that a cyclization/ring-opening mechanism needed less energy than the fragmentation and recombination mechanism.

Ribonucleoside triphosphate reductase from Lactobacillus leichmannii catalyzes the homolytic cleavage of the carbon-cobalt bond of adenosylcobalamin (AdoCbl) at a much faster rate than the uncatalyzed reaction. Evidence for the thermodynamic basis of this reaction was garnered using the kinetics of cob(II)alamin formation, as well as the measurements of the amounts of cob(II)alamin formed as a function of AdoCbl concentration and temperature. Findings also reveal that the enzyme perturbs the equilibrium between the reactant and the product thiyl radical states.

The structural, molecular and spectroscopic properties of B12 cobaloxime and imine/oxime model complexes were investigated. Experimental results showed that the cobaloximes with pyridine and benzimidazole ligands exhibit an A-type conformation regardless of the strength of the trans influence of the ligand opposite to the N-donor heterocyclic ligand. Slight reduction of the van der Waals parameters for both the N donors and the C(sp(super 2)) atoms linked to the N donors improved the fit of the calculated and experimental structures of the model complexes.

A study is conducted on the crystals of chloro- and azidocobalamin containing LiCl, C62H103Cl3CoLi2N13O21.5P and C62H106.60Cl2CoLi2N16O23.3P to assess the interactions between corrin and ionic species. The crystals were prepared using the hanging-drop method of vapor diffusion while crystal structure was determined via the X-ray diffraction beamline of the Elettra Synchrotron. It is shown that the corrin functions as a molecular 'octopussy' which 'clutch' anions and cations through its amide side chains.