Free Methionine Research Articles

Decreased levels of urinary free amino acids in children with autism spectrum disorder

Autism spectrum disorder (ASD) is a range of neurodevelopmental problems without certain causes. Conventional diagnostic or screening tools for ASD rely on the observation of children’s behavioral presentations. Novel methods are focused on the alterations of some important biochemical matters in ASD patients, which are applicable in the screening for ASD. This study investigated and compared amino acids in the first morning urine from age and sex matched ASD and non-ASD children using high performance liquid chromatography. Significantly lower urinary free methionine, phenylalanine, valine, tryptophan, and leucine plus isoleucine were observed in ASD children. The effects of using urinary free amino acids (UFAAs) singly or conjointly to classify participants into ASD or control group were analyzed and compared. ROC curves on these UFAAs singly in classification performed the sensitivity of 0.593–0.889 and the specificity of 0.704–0.963. Binary-logistic regression analysis of these UFAAs obtained a final regression model comprised of urinary free valine and tryptophan. The ROC curve established by the linear combination of the two amino acids achieved a sensitivity of 0.926 and a specificity of 0.889, which showed superiority to single UFAA and comparability to existing diagnostic or screening tools. It was suggested that the multivariate model based on UFAAs was possibly applicable in screening for children at higher risk of ASD.

Biochemical events during somatic embryogenesis in Coffea arabica L.

Several biochemical components associated with different stages of somatic embryogenesis in coffee (Coffea arabica L.) are investigated using foliar explants. Soluble sugar, starch, free amino acids and total proteins were extracted and quantified at different stages of somatic embryogenesis, such as foliar segments (initial explants), primary calluses, embryogenic calluses, globular embryos, torpedoes, cotyledonary embryos and mature fruit zygotic embryos. Total soluble sugar levels increased sixfold at the initial stages of somatic embryogenesis induction. During this period, total soluble sugar in the cultures contained approximately 99.3% glucose and fructose. At 67.4μg/mg MS, no significant changes were observed in total sugar content during the embryo's somatic maturation and regeneration. During this stage, total soluble sugar was composed of 60% sucrose. After primary callus formation, starch contents increased gradually until the culture's conclusion. Total free amino acids, particularly arginine, lysine, methionine, asparagine, glutamine and histidine, revealed a higher synthesis until the formation of the primary callus, after which they remain statistically constant up to the end of the process. During the induction of calluses, a gradual increase of total proteins occurred, which, in the differentiating and maturing of somatic embryos, did not differ statistically till the formation of a cotyledonary embryo, when rates decreased 21.8%.

Relevance of plasma levels of free homocysteine and methionine as risk predictors for ischemic stroke in the young

The debated vascular risk potential of total homocysteine (tHcy), due to failed clinical trials designed on B vitamin supplementation, raises many possible explanations like the higher risk potential of the deleterious, free form of homocysteine (fHcy) or, the unchecked confounding effects of B-vitamins in tHcy-based association studies. Additionally, the cardiovascular risk probability of altered status of the homocysteine precursor, methionine (tMet) could shed light on the causality of association between tHcy and cardiovascular diseases. Hence, we aimed to evaluate the risk associations of elevated plasma levels of tHcy, fHcy and low levels of tMet with premature, ischemic stroke. We recruited 171 young, ischemic stroke patients (aged ≤45 years) and 249 age- and gender-matched healthy controls. Plasma levels of fHcy, tHcy, tMet and vitamin B6 were estimated using HPLC coupled with coulometric electrochemical detection. Plasma levels of vitamin B12 and folate were estimated by radioimmunoassay. Elevated fHcy (>2.9μmol/L) was independently and strongly associated with the risk of premature, ischemic stroke (OR=9.62, 95% CI=3.51-26.40). On the contrary, association between premature ischemic stroke and elevated tHcy (>15.0μmol/L) was found to attenuate when adjusted for vitamin B6 values (OR=0.24, 95%, CI=0.03-1.69). Interestingly, compromised B6-status (<59.2nmol/l) was found to confer high risk of premature ischemic stroke (OR=170.80, 95% CI=58.22-501.06). We could not establish any significant correlation between fHcy and B-vitamin levels (P>0.05). Low tMet (<13.86μmol/L) was also not significantly associated with premature, ischemic stroke (OR=2.53, 95%CI=0.613-10.38). Our results indicate significant but not-correlated, independent associations of fHcy and vitamin B6 with risk of premature, ischemic stroke. However, the causality of these associations need prospective and large scale validations. Further, our findings highlight the crucial confounding effects of B-vitamins on risk association between tHcy and premature ischemic stroke.

Concurrent Overexpression of Arabidopsis thaliana Cystathionine γ-Synthase and Silencing of Endogenous Methionine γ-Lyase Enhance Tuber Methionine Content in Solanum tuberosum.

Potatoes (Solanum tuberosum) are deficient in methionine, an essential amino acid in human and animal diets. Higher methionine levels increase the nutritional quality and promote the typically pleasant aroma associated with baked and fried potatoes. Several attempts have been made to elevate tuber methionine levels by genetic engineering of methionine biosynthesis and catabolism. Overexpressing Arabidopsis thaliana cystathionine γ-synthase (AtCGS) in S.tuberosum up-regulates a rate-limiting step of methionine biosynthesis and increases tuber methionine levels. Alternatively, silencing S.tuberosum methionine γ-lyase (StMGL), which causes decreased degradation of methionine into 2-ketobutyrate, also increases methionine levels. Concurrently enhancing biosynthesis and reducing degradation were predicted to provide further increases in tuber methionine content. Here we report that S.tuberosum cv. Désirée plants with AtCGS overexpression and StMGL silenced by RNA interference are morphologically normal and accumulate higher free methionine levels than either single-transgenic line.

Determination of free methionine in human blood plasma by species-specific isotope dilution HPLC-ICP-MS using34S-labelled methionine

Determination of free methionine in human blood plasma by HPLC-ICP-MS using34S-labelled methionine as species-specific spike.

Influences of dietary protein sources and crude protein levels on intracellular free amino acid profile in the longissimus dorsi muscle of finishing gilts.

BackgroundThe current study was carried out to determine effects of dietary protein source and crude protein (CP) level on carcass characteristics, meat quality, and muscle amino acid (AA) profile in finishing gilts. The experiment was designed as a 2 × 2 factorial arrangement with two sources of dietary proteins (cottonseed meal, CSM vs. soybean meal, SBM) and two levels of CP (12 % vs. 14 %, as-fed basis). Seventy-two crossbred gilts (89.5 ± 0.9 kg) were allotted to one of four dietary treatments in a randomized complete block design for a period of 28 d. All diets were formulated to be isoenergetic and similar concentrations of standardized ileal digestible essential AA covering the nutrient requirements of pigs.ResultsGrowth, carcass characteristics and meat quality were not affected by dietary protein source nor crude protein level (P > 0.10) except that average daily feed intake was increased by CSM diets (P = 0.03). Gilts offered reduced protein diets had lower muscle pH45min (P < 0.05). Neither dietary protein source nor crude protein level influenced N deposition. However, reduced protein diets decreased N intake, N excretion, and serum urea nitrogen content, whilst improved N efficiency (P < 0.01). CSM diets increased N intake (P = 0.04), but did not depress N efficiency. The concentrations of phenylalanine, tryptophan, cysteine and tyrosine (P < 0.05) of the longissimus muscle were decreased when gilts offered CSM diets, while muscle intracellular free valine concentration was increased (P = 0.03). The gilts offered reduced protein diets had greater intracellular concentrations of free methionine, lysine, and total AA in muscle (P < 0.05).ConclusionThese results suggest that CSM could replace SBM as a primary protein source in finishing pig diets in terms of performance, N efficiency, carcass characteristics, and meat quality, but decrease the concentrations of muscle specific AA. Furthermore, the reduced protein diet played an important role in increasing muscle intracellular concentrations of specific free amino acids (FAA), and in reducing the relative ratios of specific FAA to lysine in longissimus dorsi muscle of pig, whose biological meaning needs further studies.Electronic supplementary materialThe online version of this article (doi:10.1186/s40104-015-0052-x) contains supplementary material, which is available to authorized users.

Selective Oxidation of Methionine and Tryptophan Residues in a Therapeutic IgG1 Molecule

Oxidation of methionine and tryptophan are common degradation pathways for monoclonal antibodies and present major analytical challenges in biotechnology. Generally, protein oxidation is detectable in stability and/or stressed samples (e.g., exposed to hydrogen peroxide, UV light, or metal ions). The induced chemical modifications may impact the biological activity of antibodies and may have biological consequences. However, these effects and the contribution of individual protein modifications are difficult to delineate as different amino acids are often oxidized simultaneously and accompanied by other degradants such as aggregates, especially in forced degradation studies. Here, we report a new method to obtain selective oxidation of methionine or tryptophan by using oxidation reagents combined with large excess of free tryptophan or methionine, correspondingly. More specifically, using hydrogen peroxide or tert-butyl hydroperoxide in combination with addition of free tryptophan allowed for selective oxidation of methionine. Conversely, the use of 2,2-azobis(2-amidinopropane) dihydrochloride in combination with free methionine resulted in selective tryptophan oxidation, whereas methionine oxidation was not significantly altered. This novel stress model system may prove to be valuable tool in future mechanistic studies of oxidative degradation of protein therapeutics.

Metabolic Response of Escherichia coli upon Treatment with Hypochlorite at Sub-Lethal Concentrations

Hypochlorite is a reactive oxygen species that is worldwide as an antibacterial disinfectant. Hypochlorite exposure is known to cause oxidative damage to DNA and proteins. As a response to these effects, the metabolite profiles of organisms treated with sub-lethal doses of hypochlorite are assumed to be severely modified; however, the nature of these changes is hardly understood. Therefore, using nuclear magnetic resonance spectroscopy and gas chromatography-coupled mass spectrometry, we analyzed the time-dependent impact of hypochlorite exposure with a sub-lethal concentration (50 µM) on the metabolite profile of the Escherichia coli strain MG1655. Principle component analysis clearly distinguished between the metabolite profiles of bacteria treated for 0, 5,10, 20, 40, or 60 min. Major changes in the relative amounts of fatty acids, acetic acid, and formic acid occurred within the first 5 min. Comparative gas chromatography-coupled mass spectrometry analyses revealed that the amounts of free methionine and alanine were significantly decreased in the treated cells, demonstrating their susceptibility to hypochlorite exposure. The concentrations of succinate, urea, orotic acid, 2-aminobutyric acid, and 2-hydroxybutyric acid were also severely affected, indicating general changes in the metabolic network by hypochlorite. However, most metabolite levels relaxed to the reference values of untreated cells after 40–60 min, reflecting the capability of E. coli to rapidly adapt to environmental stress factors such as the presence of sub-lethal oxidant levels.

Juvenile Atlantic salmon decrease white trunk muscle IGF-1 expression and reduce muscle and plasma free sulphur amino acids when methionine availability is low while liver sulphur metabolites mostly is unaffected by treatment

We previously reported that juvenile Atlantic salmon with mean initial BW 11.5 g offed a methionine deficient diet had lower weight gain due to a reduced protein accretion, while lipid gain was unaffected. Muscle of the fish fed the methionine deficient diet was depleted for sulphur amino acids, while in liver, the concentration of these metabolites was maintained within narrow limits. We speculated whether this could be due to an increased muscle proteolysis to support a prioritized liver metabolism in fish fed the low methionine diets. In this study, we assessed whether genes associated with muscle proteolysis increased under methionine deficiency. The composition of the diets was similar to those used previously containing 1.6 or 2.1 g Met/16 g N. We confirmed that the fish fed the low methionine diet gained less protein compared to fish fed the DL-methionine enriched diet (P = 0.014), but growth did not reduce significantly. Also the deficient fish maintained the concentrations of liver sulphur amino acids and reduced muscle free methionine. Several of the other free amino acids within muscle increased. Further, methylation capacity was maintained in liver but reduced in the muscle (P = 0.78 and 0.04, respectively). Gene expression of muscle IGF-1 was lower (P = 0.008) and myosin light chain 2 tended (MLC2, P = 0.06) to be reduced in fish fed low methionine diet, concurrently the activity of cathepsins B+L increased (P = 0.047) in muscle of fish fed the low methionine diet. Gene expression of the muscle-specific E3 ubiquitine ligases (Murf and MaFbx) was not affected by treatment. Thus, the lower protein gain observed in fish fed the low methionine diet may be caused by reduced protein synthesis in line with the reduced IGF-1 gene expression in the white trunk muscle. Thus, to support metabolism, the dietary protein needs to be balanced in amino acids to support metabolism in all compartments of the body and secure maximal protein gain.

Nutrient Composition and Phytochemical Screening of Crushed, Toasted and Fermented Roselle (Hibiscus sabdariffa L) Seeds

Aims: To examine the effects of crushing (CRRS), Toasting (TRS) and fermentation (FRS) on the nutrient composition and phytochemical constituents of Roselle seeds (Hibiscus sabdariffa). Study Design: Rosselle (Hibiscus sabdariffa L) seeds were divided into three (3) and subjected to crushing, toasting and fermentation processing methods. Duplicate samples of 100 grams each of the processed Roselle seeds were subjected to proximate analysis, amino acid evaluation, mineral determination and phytochemical screening while data collected were analysed using one-way ANOVA Place and Duration of Study: Livestock Unit of Faculty of Agriculture, Nasarawa State University Keffi, ShabuLafia Campus and the Nutrition Laboratory of the university between October 2014 Original Research Article Ari et al.; ARRB, 7(1): 39-44, 2015; Article no.ARRB.2015.103 40 and November 2014. Methodology: Raw Roselle seeds were subjected to three (3) processing methods viz: crushing (T1), toasting (T2) and fermentation (T3).Duplicate samples of each of the processed Roselle seeds were subjected to proximate analysis, amino acid evaluation, mineral determination and phytochemical screening. Results: Crude Protein (CP), Crude Fat (EE), Crude Fibre (CF), Total Ash, Dry matter (DM), Nitrogen Free Extract (NFE), Methionine, Lysine and Tryptophan values showed significant (P=0.05) increase with fermentation. Na, K, Ca and P were significantly (P=0.05) affected by processing. Phytochemicals screening indicates the presence of alkaloids, saponin, and phenols in an appreciable amount in the crushed and fermented while tannin, flavonoids and glycosides are present in moderate amounts; phlobatannin was found to be moderately present only in fermented Roselle seeds. Conclusion: Nutrient improvement and the preservation of most phytochemical constituents of Roselle seeds was best achieved through fermentation process.

Comparative Study of Indian Varieties of Lablab and Field Bean for Phenotypic and Nutritional Traits

Through varietal improvement, bushy and determinate and indeterminate Lablab bean ( Lablab purpureus var. typicus Prain) and Field bean ( Lablab purpureus var. lignosus Prain) varieties were developed in India. A comparative study among the improved cultivars for phenotypic and nutritional traits was attempted. The phenotypic traits selected for comparison are growth habit, earliness and yield. The nutritional traits studied include crude fiber, protein content, free amino acids, tryptophan, methionine and proline and the anti-nutritional traits include trypsin inhibitors, tannic acid and total phenols. The determinate bushy varieties are early, do not require any support for growth with desirable pod traits suitable for human consumption. There is variation in proximate principle content, nutritional parameters (free amino acids, methionine, tryptophan and proline) and anti-nutritional contents trypsin inhibitors, tannic acid and total phenol in different varieties of Lablab and Field beans. There is a great scope to develop varities of Labab bean having good balance between nutritional and anti-nutritional factors. Soaking, germination and cooking of beans hold a good promise for improving the nutritional value of lablab/ field beans by reducing the anti-nurtritional factors.

Pertinent plasma indicators of the ability of chickens to synthesize and store lipids.

Excessive deposition of body fat is detrimental to production efficiency. The aim of this study was to provide plasma indicators of chickens' ability to store fat. From 3 to 9 wk of age, chickens from 2 experimental lines exhibiting a 2.5-fold difference in abdominal fat content and fed experimental diets with contrasted feed energy sources were compared. The diets contained 80 vs. 20 g of lipids and 379 vs. 514 g of starch per kg of feed, respectively, but had the same ME and total protein contents. Cellulose was used to dilute energy in the high-fat diet. At 9 wk of age, the body composition was analyzed and blood samples were collected. A metabolome-wide approach based on proton nuclear magnetic resonance spectroscopy was associated with conventional measurements of plasma parameters. A metabolomics approach showed that betaine, glutamine, and histidine were the most discriminating metabolites between groups. Betaine, uric acid, triglycerides, and phospholipids were positively correlated (r > 0.3; P < 0.05) and glutamine, histidine, triiodothyronine, homocysteine, and β-hydroxybutyrate were negatively correlated (r < -0.3; P < 0.05) with relative weight of abdominal fat and/or fat situated at the top of external face of the thigh. The combination of plasma free fatty acids, total cholesterol, phospholipid, β-hydroxybutyrate, glutamine, and methionine levels accounted for 74% of the variability of the relative weight of abdominal fat. On the other hand, the combination of plasma triglyceride and homocysteine levels accounted for 37% of the variability of fat situated at the top of external face of the thigh. The variations in plasma levels of betaine, homocysteine, uric acid, glutamine, and histidine suggest the implication of methyl donors in the control of hepatic lipid synthesis and illustrate the interplay between AA, glucose, and lipid metabolisms in growing chickens.

Effect of starter cultures and packaging methods on amino acid profile and eating quality characteristics of pork ham.

Wet cured pork hams were inoculated with a mixed starter cultures comprising of Lactobacillus acidophilus and Micrococcus varians M483 at the dose level of 106cfu/g and the un inoculated hams served as controls. The amino acid profile of hams of the treated and the control groups stored at 4oC under MAP and VP and evaluated on 60th day of storage revealed that treated hams liberated higher concentration of free amino acids except for proline and methionine which were found in higher concentration (P < 0.01) in the MAP control samples. The MAP control samples liberated glutamic acid (85.65 ± 1.40ppm), cystine (21.56 ± 1.14ppm) and tyrosine (16.63 ± 1.94ppm) whereas, the treated samples did not release these amino acids. The VP control samples too liberated cystine (6.98 ± 1.36ppm) and arginine (42.70 ± 2.78ppm) but the treated ham of the VP did not liberate these amino acids. The VP hams had higher concentration (P < 0.01) of free proline, glycine, alanine, valine, methionine, isoleucine, phenylalanine, lysine and histidine than the MAP samples. Colour analysis of ham using CIE Lab colour system revealed that the treated samples had significantly higher concentrations of L*, a* and b* components. The L* and a* values were higher in the MAP than under VP systems while the b* values were higher in the VP samples than the MAP samples. Neither the bacterial cultures nor the packaging system influenced the textural property of ham. Starter cultures inoculated hams were rated superior (P < 0.05) in terms of their sensory properties. Hams packaged under MAP were rated superior (P < 0.05) than those packaged under VP in terms of appearance, colour, taste, tenderness, flavour, juiciness and overall acceptability.

The significance of methionine, histidine and tryptophan in plant responses and adaptation to cadmium stress

Noccaea caerulescens (NC) and Arabidopsis halleri (AH) were studied to compare cadmiunm (Cd) accumulation and resistance. After 30, 60 and 90 days of plant cultivation in Cd contaminated soil (Cd1 = 30, Cd2 = 60 and Cd3 =&amp;nbsp;90 mg Cd/kg soil) amino acids were determined in plants. The comparison between both species showed that Cd stress resulted in different changes of amino acids levels playing a significant role in plant adaptation to Cd stress. Our analyses indicated higher accumulations of amino acids in the roots of NC compared to AH. Contrasting responses of plants to Cd contamination were confirmed in methionine metabolism. Methionine was determined only in roots of AH after 30 and 60 days of plant cultivation. Free methionine content decreased with increasing Cd contamination (Cd3 treatment &amp;ndash; 40% decrease compared to the control treatment). Our results also showed that NC contains more than 10-fold higher content of histidine than AH. These observations indicated that this amino acid may be involved in Cd resistance and accumulation by reducing oxidative damage. Tryptophan plays a major role in the regulation of plant development and in defense responses. Its significant increase for NC treatments in contrast to AH treatments was determined.

Methionine deficiency does not increase polyamine turnover through depletion of hepatic S-adenosylmethionine in juvenile Atlantic salmon.

During the last few decades, plant protein ingredients such as soya proteins have replaced fishmeal in the diets of aquacultured species. This may affect the requirement and metabolism of methionine as soya contains less methionine compared with fishmeal. To assess whether methionine limitation affects decarboxylated S-adenosylmethionine availability and polyamine status, in the present study, juvenile Atlantic salmon were fed a methionine-deficient plant protein-based diet or the same diet supplemented with dl-methionine for 8 weeks. The test diets were compared with a fishmeal-based control diet to assess their effects on the growth performance of fish. Methionine limitation reduced growth and protein accretion, but when fish were fed the dl-methionine-supplemented diet their growth and protein accretion equalled those of fish fed the fishmeal-based control diet. Methionine limitation reduced free methionine concentrations in the plasma and muscle, while those in the liver were not affected. S-adenosylmethionine (SAM) concentrations were higher in the liver of fish fed the methionine-deficient diet, while S-adenosylhomocysteine concentrations were not affected. Putrescine concentrations were higher and spermine concentrations were lower in the liver of fish fed the methionine-deficient diet, while the gene expression of SAM decarboxylase (SAMdc) and the rate-limiting enzyme of polyamine synthesis ornithine decarboxylase (ODC) was not affected. Polyamine turnover, as assessed by spermine/spermidine acetyltransferase (SSAT) abundance, activity and gene expression, was not affected by treatment. However, the gene expression of the cytokine TNF-α increased in fish fed the methionine-deficient diet, indicative of stressful conditions in the liver. Even though taurine concentrations in the liver were not affected by treatment, methionine and taurine concentrations in muscle decreased due to methionine deficiency. Concomitantly, liver phospholipid and cholesterol concentrations were reduced, while NEFA concentrations were elevated. In conclusion, methionine deficiency did not increase polyamine turnover through depletion of hepatic SAM, as assessed by SSAT activity and abundance.

Unraveling the specificities of the different human methionine sulfoxide reductases.

The oxidation of free and protein-bound methionine into methionine sulfoxide is a frequently occurring modification caused by ROS. Most organisms express methionine sulfoxide reductases (MSR enzymes) to repair this potentially damaging modification. Humans express three different MSRB enzymes which reside in different cellular compartments. In this study, we have explored the specificity of the human MSRB enzymes both by in silico modeling and by experiments on oxidized peptides. We found that MSRB1 is the least specific MSRB enzyme, which is in agreement with the observation that MSRB1 is the only MSRB enzyme found in the cytosol and the nucleus, and therefore requires a broad specificity to reduce all possible substrates. MSRB2 and MSRB3, which are both found in mitochondria, are more specific but because of their co-occurrence they can likely repair all possible substrates.

The catabolic enzyme methionine gamma-lyase limits methionine accumulation in potato tubers.

Increasing methionine in potato tubers is desirable, both to increase the availability of this limiting essential amino acid and to enhance the aroma of baked and fried potatoes. Previous attempts to elevate potato methionine content using transgenic approaches have focused on increasing methionine biosynthesis. Higher isoleucine accumulation in these transgenic tubers suggested that the potatoes compensate for increased methionine biosynthesis with enhanced catabolism via methionine gamma-lyase (MGL), thereby producing 2-ketybutyrate for isoleucine biosynthesis. In the current study, we show that potato StMGL1 encodes a functional MGL in potato tubers. In planta silencing of StMGL1 results in an increased methionine to isoleucine ratio in the free amino acid profile of potato tubers and, in some transgenic lines, elevated accumulation of free methionine. In both wild-type and transgenic tubers, the ratio of methionine to isoleucine is negatively correlated with the level of StMGL1 transcript. A three-dimensional distribution of free amino acids in potato tubers is also described.

Physiological mechanism of drought tolerance in transgenic rice plants expressing Capsicum annuum methionine sulfoxide reductase B2 (CaMsrB2) gene

The methionine sulfoxide reductase B2 (MsrB2) gene catalyzes the reduction of free and protein-bound methionine sulfoxide to methionine and is known to provide tolerance to biotic and abiotic environmental stresses. There are yet to be any reports that MsrB2 enhances drought tolerance. Two drought-tolerant transgenic rice lines, L-8 (single copy) and L-23 (two copy), expressing the Capsicum annuum MsrB2 (CaMsrB2) gene were selected for stress tolerance phenotyping under drought stress conditions. CaMsrB2 enhanced relative water content, maintained substantial quantum yield (Fv/Fm ratio), and subsequently improved photosynthetic pigments. Interestingly, L-23, carrying two-copy T-DNA insertion, showed greater drought tolerance through more effective stomatal regulation, carotenoid concentration, and osmotic potential than the wild type. High-tech infrared technology (FLIR SC620) was used for the selection of stress-tolerant physiotypes. Later, the IR results were correlated with other tested physiological parameters. The IR images, average plant temperature, and physiological parameters of the treated plants are discussed in detail.

Methionine Metabolism in Humans: New Perspectives on Epigenetic Inheritance

Epigenetic control by methylation is directly dependent on SAM/methionine. Free methionine aside from being used for protein synthesis is activated to universal methyl group donor SAM and the methyl group from it can be transferred mainly onto DNA, histones, mRNA and noncoding (Nc) RNA, in the nucleus and onto various cytosolic recipients by specific methyltransferases. The product S-adenosylhomocysteine (SAH) from methyltransferase reaction is cleaved into free homocysteine and adenosine. Homocysteine has two fates, one to enter methionine resynthesis which requires methionine synthase (MetS), the coenzymes N5-methyltetrahydrofolate (vitamin B9) and methylcobalamin (vitamin B12). The second option of homocysteine is to enter cysteine synthesis pathway which requires cystathionine -synthase (CBS), serine, vitamin B6 (pyridoxal phosphate) and cystathionine γ-lyase (CGL). I predict serine and vitamin B6 are the critical diverting factors in a fully developed organism where the methylation is minimal and all other factors such as MetS, B9, B12, ATP, Methionine adenosyltransferase (MAT), are more relevant during normal development or in abnormal deregulated cancer cell metabolism. In a developed organism the demethylation pathway would play a critical role during tissue regeneration and must involve hydroxylation (CH2OH), oxidation (CHO) and decarboxylation (COOH) and the corresponding hydroxylase, oxidase and decarboxylase. The hydroxylation is predicted to involve vitamin C (ascorbate) and decarboxylation would involve (vitamin B6). The control of methylation and equally the demethylation is extremely crucial for epigenetic control mechanisms (gene suppression/expression) and any dysregulation would cause abnormal tissues/cancer.

Cheese 'refinement' with whey B-vitamin removal during precipitation potentially induces temporal 'functional' dietary shortage: homocysteine as a biomarker.

Cottage cheese 'refinement' with massive B-vitamin losses (≈70-84%) through whey removal during precipitation may potentially induce an acute imbalance between protein/methionine load and temporal inadequacy/shortage of nutrients critical for their metabolism, i.e. B6 and B12. The temporal effect of cottage cheese consumption was evaluated using increased plasma homocysteine as a B-vitamin shortage marker. In a double-blind study, healthy, normal-weight (BMI = 22-27), premenopausal women aged 25-45 years were first given a methionine load (100 mg kg(-1), n = 15), then cottage cheese alone (500 g, ≈50 g protein, ≈1200 mg methionine, n = 49) at breakfast, and then with added B6 (2 mg, n = 8) and/or B6 + folate (1 mg + 200 mcg, n = 7). Plasma homocysteine was measured preprandially (t0) and then postprandially 5 h (t5) and ≥6-24 h. Cheese-induced homocysteine increased 28.7% (p ≤ 0.001), ≈60% of the free methionine response, remaining higher through ≥6-8 h. Co-supplementation with B6 reduced the Hcy increase by 45.0% (to 14.9%, p = 0.025), and that with B6 + folate reduced the Hcy increase by 72.3% (to 7.5%, p = 0.556, NS). Homocysteine increased more in participants with lower baselines (<5 μM vs. ≥5 μM, p ≤ 0.001) following cheese, ≈3-fold (54.8% vs. 18.5%) or methionine, 47.3% (266.7% vs. 181.1%). Cheese B-vitamin depletion - i.e. to B6 ≈ 2.0-4.0 μg g(-1) protein, far below women's metabolic requirement (15-20 μg g(-1)) - appeared to induce acute relative shortage compared to methionine/protein loads, exemplified by greater homocysteine increases than with other animal proteins (previous data), more so with lower baseline homocysteine. Smaller increases following re-supplementation demonstrated potential for 'functional fortification'/co-supplementation. Unnoted cheese 'refinement', like white bread, potentially induces episodic vitamin shortage effects, warranting consideration for acute/cumulative implications, alternative processing/supplementation technologies, and food combinations, especially for at-risk populations (i.e. with genetic, hormonal/gender, or aging-related predispositions), and for cardiovascular, bone, and brain health.