Low Molecular Weight Enzyme Research Articles

3D architecture and structural flexibility revealed in the subfamily of large glutamate dehydrogenases by a mycobacterial enzyme

Glutamate dehydrogenases (GDHs) are widespread metabolic enzymes that play key roles in nitrogen homeostasis. Large glutamate dehydrogenases composed of 180 kDa subunits (L-GDHs180) contain long N- and C-terminal segments flanking the catalytic core. Despite the relevance of L-GDHs180 in bacterial physiology, the lack of structural data for these enzymes has limited the progress of functional studies. Here we show that the mycobacterial L-GDH180 (mL-GDH180) adopts a quaternary structure that is radically different from that of related low molecular weight enzymes. Intersubunit contacts in mL-GDH180 involve a C-terminal domain that we propose as a new fold and a flexible N-terminal segment comprising ACT-like and PAS-type domains that could act as metabolic sensors for allosteric regulation. These findings uncover unique aspects of the structure-function relationship in the subfamily of L-GDHs.

Dual-Specificity Phosphatases in Neuroblastoma Cell Growth and Differentiation.

Dual-specificity phosphatases (DUSPs) are important regulators of neuronal cell growth and differentiation by targeting proteins essential to neuronal survival in signaling pathways, among which the MAP kinases (MAPKs) stand out. DUSPs include the MAPK phosphatases (MKPs), a family of enzymes that directly dephosphorylate MAPKs, as well as the small-size atypical DUSPs, a group of low molecular-weight enzymes which display more heterogeneous substrate specificity. Neuroblastoma (NB) is a malignancy intimately associated with the course of neuronal and neuroendocrine cell differentiation, and constitutes the source of more common extracranial solid pediatric tumors. Here, we review the current knowledge on the involvement of MKPs and small-size atypical DUSPs in NB cell growth and differentiation, and discuss the potential of DUSPs as predictive biomarkers and therapeutic targets in human NB.

EFFECT OF BIO-STIMULATORS ON PRODUCTION OF COWPEA SEED FOR FOOD SECURITY AND WEALTH CREATION IN JUJA, KENYA

A study was done to evaluate the effect of bio-stimulators on seed production of cowpea crop in Juja, Kenya during short rains season 2014-15. Bio-stimulators are plant and animal derived substances that trigger plant processes when applied to the plants at very low concentrations. They contain amino acids, low molecular weight polypeptides, vitamins, enzymes, hormones, sugars, betaines and antioxidants. Drought causes slow rate of the majority of plant growth and development processes leading to discontinuation of cell growth, stomatal closures, increased abscisic acid and proline, drop in cytokinins levels, reduced protein synthesis and reduced activity of nitrate reductase leading to retarded growth and plant senescence. In reducing the impact of the water stress therefore, cytokinins in bio-stimulators promote growth and slow down plant senescence. Parameters investigated were germination rate, days to flowering and pod formation, number of seeds per pod, length of pods, total number of pods and weight of seeds. Results on the effect of bio-stimulators on cowpea seed production are discussed.

ChemInform Abstract: Can Experimental Electron‐Density Studies be Used as a Tool to Predict Biologically Relevant Properties of Low‐Molecular Weight Enzyme Ligands?

AbstractReview: < 100 refs.

제주 재래마와 더러브렛종과의 교잡종인 한라마 사골추출물과 효소분해물의 항산화 효과

본 연구는 제주 재래마와 더러브렛(Thoroughbred)종 교잡종인 제주산 마(한라마) 사골 추출분말(HLBE)과 효소분해물의 항산화 효과를 DPPH, ABTS 라디칼 소거능, FRAP, ORAC 방법을 이용하여 확인하기 위해 실시하였다. 말 사골 추출물은 열수로 8시간씩 3회 추출하여 혼합한 후 동결 건조하여 분말로 이용하였다. 동결 건조된 말 사골 추출물은 식품효소인 multifect PR 6L (MP), pepsin (PS), pepsin+ pancreatin 혼합효소(1:1, PSPC)를 첨가하고 4시간 동안 각 효소의 최적활성 온도인 60, 50, <TEX>$50^{\circ}C$</TEX>에서 분해하였다. 분해 후 3 kDa 이상의 분획과 이하의 분획으로 분리하였다. 말 사골추출물의 수율을 100%으로 고정하였을 때 각 효소에 의해 분해되어 분리한 3 kDa 이상의 크기의 분획의 수율은 각각 10.86%, 3.26%, 8.00%이었다. 단백질 함량은 말 사골 추출물보다 3 kDa 이하의 저분자 분획에서 유의적으로 감소하였다. MP와 PSPC처리군의 3 kDa 이하의 저분자 분획은 말 사골추출물과 3 kDa 이상의 효소분해물에 비해 유의적으로 높은 DPPH와 ABTS 라디칼 소거능과 ORAC 활성을 나타내었다. 그러나 PS처리군 내 3 kDa 이하의 저분자 분획은 MP처리군 보다 유의적으로 높은 FRAP 활성을 나타내었다. 이러한 결과는 말 사골 추출물 자체 보다는 효소를 이용하여 분리한 3kDa 이하의 저분자 펩타이드가 더욱 강한 항산화 효과를 갖는 것을 제시하는 것으로 특히 pepsin에 의해 생성된 저분자펩타이드 보다는 multifect와 pepsin+pancreatin 혼합효소(1:1)에 의해 생성된 분해물이 더욱 높은 항산화 효과를 나타내었다. 그러므로 말 사골추출물을 multifect와 pepsin+pancreatin 혼합효소(1:1)를 이용하여 효소 분해하여 얻은 3 kDa 이하의 저분자 펩타이드 분획은 항산화제로서 식품산업계에서 이용될 수 있을 것으로 예상되며 이를 뒷받침하기 위해 in vivo 테스트가 추후 진행되어야 할 것으로 판단된다. This study was conducted to evaluate the antioxidation activity of Jeju crossbred horse (Jeju native horse <TEX>${\times}$</TEX> thoroughbred) leg bone extracts (HLBE) and its enzyme hydrolysates by determination of 1,1-diphenyl-2picryl-hydrazyl (DPPH), 2,2-azino-bis(3-ethylbenzo thiazoline-6-sulfonic acid) diammonium salt (ABTS) radical scavenging activity, ferric reducing/antioxidant power (FRAP), and oxygen radical absorbance capacity (ORAC). HLBE was extracted with hot water for 24 hr and lyophilized. The lyophilized HLBE was hydrolyzed using multifect PR6L (MP), pepsin (PS), and a pepsin and pancreatin mixture (PSPC) for 4 hr at 60, 50, and <TEX>$50^{\circ}C$</TEX>, respectively. The hydrolysates were separated by a molecular weight of 3 kDa more or less. When the yield of HLBE was 100%, the yield of hydrolysates less than 3 kDa of MP, PS, and PSPC was 10.86, 3.26, and 8.00%, respectively. Enzyme hydrolysates with low molecular weight less than 3 kDa in MP and PSPC showed significantly higher DPPH, ABTS radical scavenging activity, and ORAC compared to HLBE and its hydrolysates with more than 3 kDa. However, the FRAP of the hydrolysates less than 3 kDa in PS was significantly higher than in MP. These results suggest that low molecular weight enzyme hydrolysates less than 3 kDa have more powerful antioxidation activity, especially when they are hydrolyzed by MP and PSPC rather than PS. Therefore, low molecular weight enzyme hydrolysates of HLBE hydrolyzed with MP and PSPC have significant potential as antioxidants in the food industry. Further in vivo studies are required to support the antioxidation activities of the hydrolysates in vitro.

Phenylethynyl-Butyltellurium Inhibits the Sulfhydryl Enzyme Na+, K+-ATPase: An Effect Dependent on the Tellurium Atom

Organotellurium compounds are known for their toxicological effects. These effects may be associated with the chemical structure of these compounds and the oxidation state of the tellurium atom. In this context, 2-phenylethynyl-butyltellurium (PEBT) inhibits the activity of the sulfhydryl enzyme, δ-aminolevulinate dehydratase. The present study investigated on the importance of the tellurium atom in the PEBT ability to oxidize mono- and dithiols of low molecular weight and sulfhydryl enzymes in vitro. PEBT, at high micromolar concentrations, oxidized dithiothreitol (DTT) and inhibited cerebral Na(+), K(+)-ATPase activity, but did not alter the lactate dehydrogenase activity. The inhibition of cerebral Na(+), K(+)-ATPase activity was completely restored by DTT. By contrast, 2-phenylethynyl-butyl, a molecule without the tellurium atom, neither oxidized DTT nor altered the Na(+), K(+)-ATPase activity. In conclusion, the tellurium atom of PEBT is crucial for the catalytic oxidation of sulfhydryl groups from thiols of low molecular weight and from Na(+), K(+)-ATPase.

Two β-xylanases from Aspergillus terreus: Characterization and influence of phenolic compounds on xylanase activity

Sugarcane bagasse was used as an inexpensive alternative carbon source for production of β-xylanases from Aspergillus terreus. The induction profile showed that the xylanase activity was detected from the 6th day of cultivation period. Two low molecular weight enzymes, named Xyl T1 and Xyl T2 were purified to apparent homogeneity by ultrafiltration, gel filtration and ion exchange chromatographies and presented molecular masses of 24.3and 23.60kDa, as determined by SDS–PAGE, respectively. Xyl T1 showed highest activity at 50°C and pH 6.0, while Xyl T2 was most active at 45°C and pH 5.0. Mass spectrometry analysis of trypsin digested Xyl T1 and Xyl T2 showed two different fingerprinting spectra, indicating that they are distinct enzymes. Both enzymes were specific for xylan as substrate. Xyl T1 was inhibited in greater or lesser degree by phenolic compounds, while Xyl T2 was very resistant to the inhibitory effect of all phenolic compounds tested. The apparent km values of Xyl T2, using birchwood xylan as substrate, decreased in the presence of six phenolic compounds. Both enzymes were inhibited by N-bromosuccinimide and Hg2+ and activated by Mn2+. Incubation of Xyl T1 and Xyl T2 with l-cysteine increased their half-lives up to 14 and 24h at 50°C, respectively. Atomic force microscopy showed a bimodal size distribution of globular particles for both enzymes, indicating that Xyl T1 is larger than Xyl T2.

Considering water availability and the effect of solute concentration on high solids saccharification of lignocellulosic biomass

Milliliter scale (ligno)cellulose saccharifications suggest general solute concentration and its impact on water availability plays a significant role in detrimental effects associated with high solids lignocellulose conversions. A microtumbler developed to enable free-fall mixing at dry solids loadings up to 35% (w/w) repeatedly produced known detrimental conversion trends on cellulose, xylan and pretreated lignocellulose with commercial enzymes. Despite this, high concentrations of insoluble nonhydrolysable dextrans did not depress saccharification extents in 5% (w/w) cellulose slurries suggesting mass transfer limitations may not significantly limit hydrolysis extents at high solids loadings. Interestingly, cellulose saccharification by purified cellulases showed increased conversions with increasing dry solids loadings. This prompted investigations into impacts the concentration of soluble species, such as sugar alcohols, low molecular weight enzyme preparation components, and monomer hydrolysis products, have on the hydrolysis environment. Such substances significantly depress conversion rates and were shown to correlatively lower water activity (A(w) ) in the hydrolysis environment while high insoluble solids concentrations did not. Furthermore, low-field NMR on concentrated slurries of insoluble complex carbohydrates, including the nonhydrolysable dextrans, showed all solids constrained water significantly more than high concentrations of soluble species (inhibitory) suggesting water constraint may not be as problematic an issue at high solids loadings compared to the availability of water in the system. Additionally, the introduction of soluble species lessened overall water constraint in high solids systems and appears to shift the distribution of water away from insoluble surfaces. This is potentially a critical issue for industrial processes operating at high dry solids levels.

Cross-linking of collagen with laccases and tyrosinases

Oxidation of acid soluble collagen (ASC), collagen suspension and BrCN-peptides (BrCN-P) with tyrosinases from B. obtusa (BoT1, BoT2) and A. bisporus (AbT) and laccases from T. versicolor (TvL) and T. hirsuta (ThL) resulted in UV/VIS peaks at 475 nm and 305 nm indicating formation of reactive o-quinones and cross-linked components. Concomitant oxygen consumption was higher for the low molecular weight enzymes (TvL and BoT2) indicating limited accessibility. SDS-PAGE and SEC bands at higher MW demonstrated the formation of cross-linked material. LC-MS/MS analysis suggested the involvement of tyrosine residues in cross-linking without major changes of sequence similarities to untreated collagen. However, an increase of the SEC α-peak together with a decrease of β-peak and the 1235/1450 cm − 1 ratio (FTIR) indicated partial degradation. Crosslinking was enhanced by phenolic molecules such as catechine which lead to increased denaturation temperature and reduced degradation by microbial collagenase. The tensile strength was increased whereas resistance to compressive forces was not influenced.

Low molecular weight serine protease from the viscera of sardinelle ( Sardinella aurita) with collagenolytic activity: Purification and characterisation

A new low molecular weight (LMW) serine-protease from sardinelle ( Sardinella aurita) viscera was purified using ammonium sulphate precipitation and Sephadex G-100 gel filtration, with a 3.82-fold increase in specific activity. The molecular weight of the enzyme was estimated to be 14.2 kDa by SDS-PAGE. The optimum pH and temperature for the enzyme activity were around pH 8.0 and 60 °C, respectively. The purified protease was strongly inhibited by phenylmethylsulphonyl fluoride, a serine-protease inhibitor, and soybean trypsin inhibitor. The N-terminal amino acid sequence of the first 10 amino acids of the purified protease was APVQPCVVVI. This sequence showed low homology with several peptidases, suggesting that the enzyme is a new protease. Interestingly, the protease was found to cleave collagen type I and hydrolyze succinyl-L-Ala-L-Ala-L-Pro-L-Phe-p-nitroanilide (sAAPFpna), an amide substrate of chymotrypsin. Our findings indicate that the S. aurita protease is a new LMW enzyme with collagenolytic activity.

Purification and Characterization of a Low Molecular Weight of β-Mannanase from Penicillium occitanis Pol6

The highest beta-mannanase activity was produced by Penicillium occitanis Pol6 on flour of carob seed, whereas starch-containing medium gave lower enzymes titles. The low molecular weight enzyme was purified to homogeneity by ammonium sulfate precipitation, gel filtration, and ion-exchange chromatography procedures. The purified beta-mannanase (ManIII) has been identified as a glycoprotein (carbohydrate content 5%) with an apparent molecular mass of 18 kDa. It was active at 40 degrees C and pH 4.0. It was stable for 30 min at 70 degrees C and has a broad pH stability (2.0-12.0). ManIII showed K (m), V (max), and K (cat) values of 17.94 mg/ml, 93.52 U/mg, and 28.13 s(-1) with locust bean gum as substrate, respectively. It was inhibited by mannose with a K (I) of 0.610(-3) mg/ml. ManIII was activated by CuSO4 and CaCl2 (2.5 mM). However, in presence of 2.5 mM Co2+, its activity dropped to 60% of the initial activity. Both N-terminal and internal amino acid sequences of ManIII presented no homology with mannanases of glycosides hydrolases. During incubation with locust bean gum and Ivory nut mannan, the enzyme released mainly mannotetraose, mannotriose, and mannobiose.

Hydrolyzing Ability of Protease of Enzyme Complex of Cholera Vibrio that is Proteovibrin for Protein Substrates

The way of production of low-molecular weight enzyme complex of cholera vibrio (proteovibrin) with high proteolytic activity is described. Its prevailing accumulation in ultrafiltrate of cultural liquid of M41 production strain is shown. Proteovibrin protease doesn't yield to commercial trypsin in proteolytic activity as regards some protein substrates and can be used for enzymolysate preparation.

Reactivity of Penicillin-Binding Proteins with Peptidoglycan-Mimetic β-Lactams: What's Wrong with These Enzymes?

Beta-lactams exert their antibiotic action through their inhibition of bacterial DD-peptidases (penicillin-binding proteins). Bacteria, in general, carry several such enzymes localized on the outside of their cell membrane to catalyze the final step in cell wall (peptidoglycan) synthesis. They have been classified into two major groups, one of high molecular weight, the other of low. Members of the former group act as transpeptidases in vivo, and their inhibition by beta-lactams leads to cessation of bacterial growth. The latter group consists of DD-carboxypeptidases, and their inhibition by beta-lactams is generally not fatal to bacteria. We have previously shown that representatives of the former group are ineffective at catalyzing the hydrolysis/aminolysis of peptidoglycan-mimetic peptides in vitro [Anderson et al. (2003) Biochem. J. 373, 949-955]. The theme of these experiments is expanded in the present paper where we describe the synthesis of a series of beta-lactams (penicillins and cephalosporins) containing peptidoglycan-mimetic side chains and the kinetics of their inhibition of a panel of penicillin-binding proteins spanning the major classes (Escherichia coli PBP 2 and PBP 5, Streptococcus pneumoniae PBP 1b, PBP 2x and PBP 3, the Actinomadura R39 DD-peptidase, and the Streptomyces R61 DD-peptidase). The results of these experiments mirror and expand the previous results with peptides. Neither peptides nor beta-lactams with appropriate peptidoglycan-mimetic side chains react with the solubilized constructs of membrane-bound penicillin binding proteins (the first five enzymes above) at rates exceeding those of generic analogues. Such peptides and beta-lactams do react at greatly enhanced rates with certain soluble low molecular weight enzymes (R61 and R39 DD-peptidases). The former result is unexpected and interesting. Why do the majority of penicillin-binding proteins not recognize elements of local peptidoglycan structure? Possible answers are discussed. That this question needs to be asked casts fascinating shadows on current studies of penicillin-binding proteins for new drug design.

Analysis of expression of secreted phospholipases A 2 in mouse tissues at protein and mRNA levels

Secreted phospholipases A 2 (sPLA 2) form a group of low-molecular weight enzymes that catalyze the hydrolysis of phospholipids. Some sPLA 2s are likely to play a role in inflammation, cancer, and as antibacterial enzymes in innate immunity. We developed specific and sensitive time-resolved fluroimmunoassays (TR-FIA) for mouse group (G) IB, GIIA, GIID, GIIE, GIIF, GV and GX sPLA 2s and measured their concentrations in mouse serum and tissues obtained from both Balb/c and C57BL/6J mice. We also analyzed the mRNA expression of the sPLA 2s by quantitative real-time reverse transcriptase PCR (qPCR). In most tissues, the concentrations of sPLA 2 proteins corresponded to the expression of sPLA 2s at the mRNA level. With a few exceptions, the sPLA 2 proteins were found in the gastrointestinal tract. The qPCR results showed that GIB sPLA 2 is synthesized widely in the gastrointestinal tract, including esophagus and colon, in addition to stomach and pancreas. Our results also suggest that the loss of GIIA sPLA 2 in the intestine of GIIA sPLA 2-deficient C57BL/6J mice is not compensated by other sPLA 2s under normal conditions. Outside the gastrointestinal tract, sPLA 2s were expressed occasionally in a number of tissues. The TR-FIAs developed in the current study may serve as useful tools to measure the levels of sPLA 2 proteins in mouse serum and tissues in various experimental settings.

X-ray Structure of the R69D Phosphatidylinositol-Specific Phospholipase C Enzyme: Insight into the Role of Calcium and Surrounding Amino Acids in Active Site Geometry and Catalysis

Phosphatidylinositol-specific phospholipase Cs (PLCs) are a family of phosphodiesterases that catalyze the cleavage of the P-O bond via transesterification using the internal hydroxyl group of the substrate as a nucleophile, generating the five-membered cyclic inositol phosphate as an intermediate or product. To better understand the role of calcium in the catalytic mechanism of PLCs, we have determined the X-ray crystal structure of an engineered PLC enzyme from Bacillus thuringiensis to 2.1 A resolution. The active site of this enzyme has been altered by substituting the catalytic arginine with an aspartate at position 69 (R69D). This single-amino acid substitution converted a metal-independent, low-molecular weight enzyme into a metal ion-dependent bacterial PLC with an active site architecture similar to that of the larger metal ion-dependent mammalian PLC. The Ca(2+) ion shows a distorted square planar geometry in the active site that allows for efficient substrate binding and transition state stabilization during catalysis. Additional changes in the positions of the catalytic general acid/general base (GA/GB) were also observed, indicating the interrelation of the intricate hydrogen bonding network involved in stabilizing the active site amino acids. The functional information provided by this X-ray structure now allows for a better understanding of the catalytic mechanism, including stereochemical effects and substrate interactions, which facilitates better inhibitor design and sheds light on the possibilities of understanding how protein evolution might have occurred across this enzyme family.

Cellular Distribution, Post-translational Modification, and Tumorigenic Potential of Human Group III Secreted Phospholipase A2

Human group III secreted phospholipase A(2) (sPLA(2)-III) consists of a central group III sPLA(2) domain flanked by unique N- and C-terminal domains. We found that the sPLA(2) domain alone was sufficient for its catalytic activity and for its prostaglandin E(2) (PGE(2))-generating functions in various cell types. In several if not all cell types, the N- and C-terminal domains of sPLA(2)-III were proteolytically removed, leading to the production of the form containing only the sPLA(2) domain, which could be further N-glycosylated at two consensus sites. Immunohistochemistry demonstrated that sPLA(2)-III was preferentially expressed in the microvascular endothelium in human tissues with inflammation, ischemic injury, and cancer. In support of this, sPLA(2)-III was induced in cultured microvascular endothelial cells after stimulation with proinflammatory cytokines. Expression of sPLA(2)-III was also associated with various tumor cells, and colorectal cancer cells transfected with sPLA(2)-III exhibited enhanced PGE(2) production and cell proliferation, which required sPLA(2)-III catalytic activity. When implanted into nude mice, the sPLA(2)-III-transfected cells formed larger solid tumors with increased angiogenesis compared with control cells. Moreover, small interfering RNA for sPLA(2)-III significantly reduced PGE(2) production and proliferation of colorectal cancer cells. Taken together, these results reveal unique cell type-specific processing and N-glycosylation of sPLA(2)-III and the potential role of this enzyme in cancer development by stimulating tumor cell growth and angiogenesis.

Evolutionary aspects of the gene for the classical enzyme polymorphism, ACP1

The gene for the classical polymorphic marker, ACP1, contains an unusual construction, two alternative exons, 3F and 3S, interspaced by a short 41-bp non-coding sequence, too short to function as a normal intron. During processing, two different mRNAs are produced, one containing 3F, the other 3S, resulting in the expression of two isoforms of the enzyme in human tissues. The fast and slow isoforms have different enzymatic properties and may have different physiological functions. This low molecular weight enzyme seems to function as a protein phosphotyrosine phosphatase (LMPTP). The LMPTP gene is highly conserved through evolution and has been found all the way back to yeasts, however, these express only one isoform. The ability to generate two functionally different isoforms by alternative splicing may be of evolutionary significance. We have analysed various species for LMPTP isoforms and gene structure. Two isoforms with different properties were observed in mammals and in fish, even in the evolutionary old shark. Exons similar to the human 3F and 3S were detected in cow, pig and cod, however, the intron between them is longer, 47 bp in cow and pig and 56 bp in cod.

Simultaneous detection of ACP1 and GC genotypes using PCR/SSCP.

The classical enzyme and protein markers ACP1 and GC have gained new importance because of the biological functions of their gene products. ACP1 encodes a low molecular weight enzyme which is now recognized as a phosphotyrosine phosphatase with a role in the regulation of signal transduction pathways, and GC-globulin acts both as a transporter of vitamin D and as a plasma actin scavenger and plays a role in macrophage activation. These two polymorphisms were phenotyped for decades on the basis of electrophoretic isozyme or protein patterns; the gene structures are now known. Nucleotide substitutions determining the common alleles are close enough at each locus to be contained in one short PCR product. We have developed a simple, rapid and reliable multiplex method based on PCR and SSCP which allows the simultaneous determination of the common ACP1 and GC genotypes.

Diet restriction in mice causes differential tissue responses in total reducing power and antioxidant compounds.

Diet restriction (DR) has been shown to extend the life spans of various laboratory animals, the mechanism may involve a decrease in oxidative stress. When determining if the total tissue defense has been altered, it is important to observe the overall direct antioxidant capacity, which consists of low molecular weight antioxidants (LMWA) and enzymes. To determine DR induced changes in total reducing power and overall direct antioxidant capacity of various mouse tissues. Young female Sabra mice were fed a 60% food restricted diet for 40 days (DR group). Organs of the DR group and of ad libitum (AL) fed controls were then dissected and examined. A cyclic voltammetry method was used to quantify the total reducing power, which correlates with the overall LMWA activity. Specific LMWA were identified by HPLC-ECD. Superoxide dismutase activity and H2O2 degrading ability were measured in order to include the enzymatic antioxidant component. Short-term DR caused alterations in the total reducing power of various mouse tissues, indicating changes in the total scavenging ability of these tissues. Overall direct antioxidant capacity of heart, kidney and muscle was enhanced; liver and small intestine deteriorated; brain did not differ between DR and AL groups; lung and spleen exhibited a mixed response. We have shown for the first time that DR causes changes in the total reducing power of different mouse tissues, thus, affecting the overall direct antioxidant capacity. These findings support the suggestion that there may be a biological regulation of the antioxidant system.

Prospects for nutritional interventions in the clinical management of Fanconi anemia.

The evidence associating Fanconi anemia (FA) phenotype to in-vitro and ex-vivo oxidative stress is reviewed. A cancer-prone genetic disease, FA is characterized by delayed bone marrow failure with a progression to aplastic anemia. It is diagnosed by excess chromosomal instability induced by two clastogens, either diepoxybutane (DEB) or mitomycin C (MMC). Clinical symptoms vary in a broad range including a life-threatening hematological impairment, and an extended set of developmental abnormalities, growth retardation and skin pigmentation. Cancer-proneness in FA results in excess incidence of non-lymphoblastic leukemias, and of some defined solid tumors. The relationships of oxidative stress with FA phenotype rely on a consistent body of evidence that includes: (1) excess formation of DNA oxidative damage (both in vitro and in vivo); (2) cellular protection by hypoxia, low molecular-weight antioxidants, antioxidant enzymes, and thioredoxin overexpression; (3) impaired expression and/or activity of antioxidant enzymes, and (4) the redox-dependent action mechanisms of MMC and DEB. This evidence points to a re-appraisal of FA phenotype, suggesting a causative role for oxidative stress in disease progression towards malignancies and/or bone marrow depletion. A well-established literature reporting epidemiological and experimental data provides the nutritional bases for cancer control. Thus, the present state-of-the-art in the related fields of oxidative stress, nutrition, cancer-proneness and FA phenotype, altogether implies the need to undertake the most appropriate efforts to counteract oxidative stress in the clinical management of FA patients.