Effects of compound protein powder on nitrogen metabolism and physiological and biochemical indexes in rats / 公共卫生与预防医学

Objective To explore the nutritional efficacy of compound protein powder formulations from different sources. Methods Three groups of compound protein powder formulations were obtained through scientific blending using soy protein, whey protein and yeast protein as raw materials. The effects of the compound protein powders on nitrogen metabolism, serum biochemical indicators, and pathological changes of liver tissue and epididymal fat in rats were evaluated. Results Compared with the control (casein), the net protein utilization, biological evaluation, and protein efficacy ratio of the compound protein powders in rats were significantly improved, and the changes in these indicators in the formula with the highest whey protein content were most significant among all three formulas. The compound protein powders effectively increased the levels of albumin and globulin, while decreased the content of total cholesterol, indicating beneficial effects on improving immunity and controlling lipid metabolism, with the formula group 2 being the most effective among all three groups. The pathological examination showed that the three groups of protein powder did not have adverse effects on liver tissue and epididymal fat. Conclusion The present study demonstrates that the compound protein powder formulation has nutritional value, which suggests a potential of the application of the compound protein powder formulation in the elderly, and people with special nutritional needs, such as sports people.

Mechanism exploration on nitrogen metabolism and secondary metabolism in Atropa belladonna hairy roots treated with yeast extract / 中国中药杂志

In order to study the mechanism of nitrogen metabolism and secondary metabolism in Atropa belladonna hairy roots treated with yeast extract, yeast extract（YE） was added to the culture medium. Then the changes of physiological and biochemical indexes of A. belladonna hairy roots after treatment with YE were detected. The results are as follows，the activity of key enzymes of nitrogen metabolism changed differently. Compared with the control group (CK), the activity of nitrate reductase (NR) and glutamine synthetase (GS) were significantly increased, while the activity of glutamate dehydrogenase (GDH) was not changed significantly. The content of nitrate nitrogen, ammonium nitrogen had a significant decrease,but the content of soluble protein, free amino acid, total nitrogen are significantly more than CK. Moreover, YE treatment led to the increase of the content precursor amino acids (ornithine and arginine) and precursor putrescine in secondary metabolic pathways of A. belladonna. The expression level of gene putrescine N-methyl transferase (pmt), tropinone reductase-I (trI) and hyoscyamine 6-β-hydroxylase(h6h) all increased in a different rate caused by YE treatment, which eventually led to the increase of the yield of tropane alkaloids. The yield of hyoscyamine and scopolamine were 3.09 and 1.85 folds than that of CK after 16 days treatment time. The results indicated that YE can induce more synthesis of tropane alkaloids by increasing the activity of key enzymes in nitrogen metabolism to provide more synthetic materials for secondary metabolism, meanwhile it regulated the expression level of some genes of key metabolic enzyme to accelerate secondary metabolism.

Characterization of glutamate dehydrogenase SHJG 7666 from Streptomyces hygroscopicus 5008 / 中国药科大学学报

Glutamate dehydrogenase (GDH)a key enzyme in the nitrogen metabolism pathway catalyzes the con-version between α-ketoglutarate and glutamate reversibly using NAD(P)H as a cofactor. Based on genomic stud-ies,it was concluded that SHJG_7666 was a potential GDH in Streptomyces hygroscopicus 5008(S5008),and its expression level in vivo was positively correlated with the biosynthesis of an important aminocyclol compound vali-damycin. Phylogenetic tree analysis showed that the S5008 SHJG_7666 GDH belonged to the Glu/Leu/Phe/Val dehydrogenase family,with conserved glutamate-α-ketoglutarate binding domain and the classical GXGXXG dinu-cleotide binding motif. Further homologous modeling and structural comparison revealed that SHJG_7666 con-tained conserved Lys60,Lys78and Asp120catalytic functional sites and ligand binding residues Ser36,Gly38,Gln119 and Asp166,Asn300,Ala330. Moreover,recombinant expression of SHJG_7666 in E. coli and in vitro enzyme activity demonstrated that glutamate dehydrogenase can convert ammonium salt to glutamate with pH and temperature being optimal at 7. 5 and 37 °C respectively. Enzyme activity under optimum reaction condition has Kmvalue of (25. 3 ±9. 1)μmol/L and kcatof (3 ±0. 8)×10 -5s-1for the substrate α-ketoglutarate. Results of this study further improved the catalytic activity of SHJG_7666,thus laying the foundation for the ultimate increase of vali-damycin production.

Redução da proteína bruta em rações sobre os balanços metabólicos de suínos mantidos em diferentes condições térmicas / Reducing crude protein in diets on the metabolic balances for pigs kept in different thermal conditions

O objetivo deste trabalho foi avaliar a redução da proteína bruta em rações sobre o balanço de nitrogênio, pH urinário e parâmetros sanguíneos de suínos na fase inicial. O peso médio inicial dos animais foi de 18,5 ± 0,73kg. Foram realizados dois experimentos de digestibilidade, sendo um em condições de ambiente de estresse (28,77˚C) e outro conforto térmico (18,13˚C). Em ambos os experimentos os animais foram distribuídos em um delineamento experimental de blocos ao acaso com quatro níveis de proteína bruta (20,5;19,4; 18,3 e 17,2%) e quatro repetições, totalizando 16 unidades experimentais em cada experimento, sendo cada uma representada por um animal, totalizando 32 animais. A metodologia utilizada foi a coleta total de fezes, e a urina coletada e filtrada diariamente. Para avaliar os parâmetros sanguíneos, as amostras foram obtidas mediante punção na veia jugular. Os parâmetros avaliados foram nitrogênio ingerido, excretado nas fezes e na urina, absorvido, retido, retido/absorvido, excreção total, utilização líquida de proteína, pH da urina, colesterol, triglicerídeos, glicose, uréia e creatinina no plasma sanguíneo. Conclui-se que a redução do nível de proteína da dieta, de 20,5 a 17,2%; é uma alternativa eficiente para reduzir a quantidade de nitrogênio excretado pelos suínos em condição de estresse térmico. Para condição de conforto térmico os suínos apresentaram maiores concentrações de creatinina e colesterol plasmático.

The objective of this study was to evaluate the reduction of crude protein diets on nitrogen balance, urinarypH and blood parameters of starter pigs. The average initial weight of the animals was 18.5 ± 0.73 kg. Two digestibility experiments were conducted, one in environmental conditions of stress (28.77 ˚ C) and another in thermal comfort condition (18.13 ˚ C). In both experiments, the animals were distributed in randomized blockswith four decreasing levels of crude protein (20.5, 19.4, 18.3 and 17.2%) and four replications, totaling 16experimental units in each experiment, each represented by an animal, totaling 32 animals. The methodology used was the total collection of feces and urine was collected and filtered daily. To assess blood parameters, samples were obtained by jugular vein puncture. The parameters evaluated were ingested nitrogen, excreted in feces and urine, absorbed, retained, retained/absorbed, total excretion, net protein utilization, urine pH,cholesterol, triglycerides, glucose, urea and creatinine in blood plasma. It is concluded that reducing the levelof protein in the diet, 20.5 to 17.2%; is an efficient alternative to reduce the amount of nitrogen excreted bypigs in heat stress condition. In thermal comfort condition pigs showed higher concentration of creatinine and serum cholesterol.

Regulation of nitrogen metabolism in salt tolerant and salt sensitive Frankia strains.

Effect of salinity (0, 50, 100, 250, 500 and 750 mM NaCl) was observed on some important physiological parameters of nitrogen metabolism such as nitrate uptake, intracellular and extracellular ammonium status and activities of nitrogenase, nitrate reductase, nitrite reductase and glutamine synthetase among Frankia strains differing in their salt tolerance capacity. Nitrogenase activity closely followed the growth pattern with regular decline on NaCl supplementation. All the other enzymes showed optimum activity at 100 mM and declined further. Co-regulation of the nitrate uptake system and sequential enzyme activities plays a crucial role in governing the nitrogen status of strains during salt stress. HsIi10 experiencing minimum decline in enzyme activities and best possible nitrogen regulation under NaCl replete condition showed adequate nutritional management. Among all the strains, HsIi10 proved to be salt tolerant on account of above features while the salt sensitive strain HsIi8 lacked the ability to regulate various steps of nitrogen metabolism during salinity, and thus Frankia strain HsIi10 can potentially serve as a potential biofertilizer in the saline soil.

Streptococcus mutans GlnK protein: an unusual PII family member

Streptococcus mutans is a Gram-positive bacterium present in the oral cavity, and is considered to be one of the leading causes of dental caries. S. mutans has a glnK gene, which codes for a PII-like protein that is possibly involved in the integration of carbon, nitrogen and energy metabolism in several organisms. To characterize the GlnK protein of S. mutans, the glnK gene was amplified by PCR, and cloned into the expression vectors pET29a(+) and pET28b(+). The native GlnK-Sm was purified by anion exchange (Q-Sepharose) and affinity (Hi-Trap Heparin) chromatography. The GlnK-His-Sm protein was purified using a Hi-Trap Chelating-Ni2+ column. The molecular mass of the GlnK-His-Sm proteins was 85 kDa as determined by gel filtration, indicating that this protein is a hexamer in solution. The GlnK-His-Sm protein is not uridylylated by the Escherichia coli GlnD protein. The activities of the GlnK-Sm and GlnK-His-Sm proteins were assayed in E. coli constitutively expressing the Klebsiella pneumoniae nifLA operon. In K. pneumoniae, NifL inhibits NifA activity in the presence of high ammonium levels and the GlnK protein is required to reduce the inhibition of NifL in the presence of low ammonium levels. The GlnK-Sm protein was unable to reduce NifL inhibition of NifA protein. Surprisingly, the GlnK-His-Sm protein was able to partially reduce NifL inhibition of the NifA protein under nitrogen-limiting conditions, in a manner similar to the GlnK protein of E. coli. These results suggested that S. mutans GlnK is functionally different from E. coli PII proteins.

Variation in the ureide content of Jack Bean during the reproductive stages in response to nitrate

Nitrogen is frequently the limiting mineral nutrient for plant productivity and it is essential to obtain an understanding of how this element is assimilated and its metabolism regulated, in crop plants. The objective of this work was to study nitrogen metabolism in the tropical legume Canavalia ensiformis, a plant species used as a green manure. The nitrate dose provided changed the concentrations of ureides exported via the xylem, whilst the developmental stage alterations demonstrated to influence the form of ureide exported via the xylem. Considering the content of ureides as an indicator of N-fixation status, it could be concluded that N-fixation was affected in the presence of nitrate in C. ensiformis.

Nitrogênio é o nutriente mineral mais limitante e importante para produção vegetal e o entendimento de como esse elemento é assimilado e como seu metabolismo é regulado, são essenciais para plantas cultivadas. O objetivo deste trabalho foi estudar as variações no metabolismo de nitrogênio em Canavalia ensiformis, em resposta ao nitrato, durante o período reprodutivo. A dose de nitrato fornecida mudou as concentrações de udeídeos exportados via xilema, enquanto alterações no estádio de desenvolvimento mostrou influenciar a forma de ureídeo exportado via xilema. Considerando o nível de ureídeos como um indicador do status da fixação biológica, é possível dizer que a fixação do nitrogênio pode ter sido afetada na presença do nitrato em C. ensiformis.

Effects of zinc on carbon and nitrogen metabolism in leaves of Pinellia ternata and their yield / 中草药

Objective To find out the proper concentration of ZnSO4?7H2O as foliar fertilizer used for Pinellia ternata, and to provide reference for high yield of P.ternate,effects of zinc on the carbon and nitrogen metabolism in leaves of P.ternata and the yield were studied.Methods Seedlings of P.ternata were employed as the experiment material.At the stage of full seedling,ZnSO4?7H2O of different concentration was sprayed on the leaves,the indexes of carbon and nitrogen metabolism were determined on the day 10,the weight of tubers and bulbils were measured at the sprout tumble stage.Results The yield of P.ternata has an exceedingly significant positive correlation with the contents of soluble sucrose and starch in the leaves,a significant positive correlation with the content of photosynthetic pigment and the aldolase activity,and a negative correlation with the amylase activity.In addition,the yield shows both an exceedingly significant positive correlation whith the nitrate reductase activity and a significant positive correlation with the content of protein.At the stage of full seedling,zinc sprayed on leaves can increase the content of photosynthetic pigment and improve the capability of photosynthesis.Meanwhile,spraying zinc can also promote the accumulation of soluble sucrose and starch in the leaves because of its stimulation on aldolase and inhibition on amylase.Besides,spraying zinc on leaves could improve the activity of nitrate reductase and the content of protein,and finally increase the yield of P.ternata.Conclusion The concentration of 600 mg/L is the best for ZnSO4?7H2O used as foliar fertilizer for P.ternate at the stage of full seedling.

Seasonal reorganization of nitrogen metabolism in an Indian airbreathing teleosts, Channa punctatus (Bloch).

Channa punctatus, an air-breathing freshwater teleost, mobilizes more protein for its energy requirement during summer and spawning months, as revealed by the data on endogenous nitrogen excretion in the form of ammonia-N, urea-N, free amino acids, creatinine and creatine.

Metabolism of mycobacteria.

The metabolism of mycobacteria have been studied with reference to carbohydrate, lipids, nitrogen metabolism and oxidative phosphorylation. Some of the enzymes of glycolytic pathway, tricarboxylic acid cycle and lypogenic enzymes were purified, characterized and their kinetic properties investigated. The effect of age of the culture and environmental factors on different aspects of metabolism of mycobacteria were also studied. A comparison of lipid profile in various species of mycobacteria grown in different culture conditions were made. The metabolism of spheroplasts isolated from mycobacteria has been established with respect to their energy charge and to synthesize peptidoglycan using D-alanine as the precursor.

Effects of Soy Hydrolyzed Peptides Supplementation on Small Intestinal Absorption in Rats / 中国运动医学杂志

Objective: To investigate the effects of soy hydrolysed peptides supplementation on small intestinal morphology and nitrogen absorption in rats,and illustrate the characteristic of absorption on soy hydro? lysed peptides supplementation in small intestinal. Methods: 30 male SD rats were randomly divided into three groups: Placebo group (water supplemented, Pla group); Isolated soy protein-supplemented group (Pro group); Soy hydrolysed peptides-supplemented group (Pep group). After one week meals adaptation, Metabolic test had done, small intestinal morphology, and the activity of aminopeptidase were determined. Results: (2) The content of intestinal epithelial protein in Pep group increased 48.60% than Pro group, and increased 91.37% than Pla group (P

STUDIES ON NiTROCGEN METABOLISM DURING ACUTE RADIATION DAMAGE / 营养学报

Studies on nitrogen metabolism in rats and dogs during acute radiation damage were made, the main results being shown as follows:1. Rats given 630 r whole body radiation showed marked decrease of food intake, but their body weight losses exceeded substantially those of non-radiated rats in pair feeding group. As compared with the latter, the former had more excretion of urinary nitrogem and negative nitrogen balance in the 1st and 2nd day following the exposure of X-ray.2. Four adult male dogs were selected as experimental animals. After irradiation of 430 r,the daily intake of protein and calories were decreased and correspondingly the excretion of total nitrogen,urea nitrogen and amino nitrogen became increased, especially in the 1st and 2nd day.3. Three groups of dogs were fed to low, moderate and high protein diet respectively. Their nitrogen balance were different but normal, however, after irradiation of 400 r the nitrogen balances in the low protein diet group became negative whereas that in the moderate or high protein diet group in general was slightly positive.