Influence of free amino acids on clavulanic acid production by Streptomyces clavuligerus in synthetic medium

The effect of nitrogen source on clavulanic acid production was investigated in shake flasks. Media containing asparagine plus one of several different amino acids or a combination of two amino acids was tested. The best result, ca. 180 mg/L clavulanic acid, CA, in 60 h, was obtained with the lysine-tyrosine pair In an aerated and agitated fermentor this medium led to CA concentrations of ca. 210 mg/L, a remarkable production for synthetic medium utilization. Amino acids analysis during cultivation indicated that, while asparagine was consumed rapidly, lysine and tyrosine were metabolized slowly, promoting CA production.

Association of free amino acids with caries experience and mutans streptococci levels in whole saliva of children with early childhood caries

Objective: The aim of the present study was to identify the free amino acid content in whole saliva of children with (CE) and without early childhood caries (CF) (ECC), correlating these findings with caries experience and mutans streptococci (MS) levels in saliva.Design: Seventy-eight healthy children, both genders, 6-71 months age, were selected to participate in the study. Following examination for dmft scores calculation, unstimulated whole saliva was collected from all 78 participants, stored at -80 degrees C, and used for amino acid analysis, on a Biochem 20 plus amino acid analyzer. Stimulated whole saliva was collected from 52 children, transported, diluted and plated on MSB agar medium for detection of MS in cfu/mL.Results: Forty different free amino acids were identified in whole saliva, with great variation in their concentration. A statistically significant relation was found between caries experience and the presence of free proline and glycine. While proline (p = 0.0182) was more frequently absent in the CF group, the absence of glycine (p = 0.0397) was more often observed in the CE group. In the presence of higher levels of MS, free glycine reduced the risk of experiencing dental caries (p = 0.0419). Conversely, the presence of proline was found to increase the risk of experiencing the disease (p = 0.0492).Conclusions: The presence of free proline and absence of free glycine in children with ECC, highly contaminated with MS, increased the chances of experiencing dental caries in the present population. Further studies are needed to better understand this phenomenon. (C) 2008 Elsevier Ltd. All rights reserved.

Effects of intrauterine malnutrition on brain free amino acids of young rats, after nutritional recovery during lactation period

The effect of protein-calorie malnutrition during gestation on the brain amino acids of rat pups was studied following nutritional recovery during lactation. The brain amino acids of rat pups born to dam rats malnourished during gestation were studied after these rat pups received proper nutrition during lactation. Pregnant rats were fed a 1% protein diet with total caloric intake restricted to half that of controls. After birth, the offspring of rats fed on deficient diets were nurtured up to the 28th day postpartum by foster mothers receiving adequate diets. At this time, the offspring were killed. The control group consisted of offspring from pregnant rats fed a diet with adequate protein (21%) and calories during the entire gestation and lactation period. Quantitation of brain amino acids in the pups at 28 days postpartum showed lower concentrations of essential and nonessential amino acids in the rats malnourished during gestation. Concentrations of histidine, glycine, and α-aminobutyric acids were all reduced. These findings demonstrate that the brains of rat pups malnourished during gestation show persistent decreases in specific brain amino acids after adequate postpartum nutrition.

Lipoic acid and ascorbic acid affect plasma free amino acids selectively in the teleost fish pacu (Piaractus mesopotamicus)

Most studies on the antioxidants, lipoic acid (LA) and ascorbic acid (AA), focused on species that, unlike teleost fish, are not scurvy-prone, and are able to synthesize AA. The antioxidant properties of LA may make it useful in aquaculture nutrition, but several effects must first be investigated, and we address here plasma free amino acids (FAA). In mammals, LA and AA in high doses were claimed to alter plasma FAA profile; to our knowledge, however, no data are available in fish. We therefore studied the effects of dietary LA and AA on plasma FAA in the South American teleost fish pacu, which is being used increasingly in aquaculture. LA treatment decreased concentrations of 18 of 23 individual FAA; specifically, dispensable and total FAA were significantly affected. Ornithine was elevated (+26%) in LA-treated fish and significantly decreased ratios of plasma [Arg]/[Orn] and other individual [FAA]/[Orn] were observed. LA and AA both affected sulfur FAA concentrations. Plasma cystine levels were significantly increased in the LA-supplemented groups. AA had little effect on most amino acids, and no interaction with LA was detected. AA supplementation did, however, significantly lower taurine (-42%) and cystathionine (-31%) levels in plasma. No effect on the branched chain:aromatic amino acid ratios was observed. The data indicate that at the dietary level studied, LA and AA independently affect selected plasma FAA in pacu, and suggest that any use of LA in particular as a dietary supplement should take into account an altered plasma FAA profile.

Free Amino Acids in Pacu, Piaractus mesopotamicus, Eggs and Larvae

Free amino acids (FAA) are used principally as substrate in protein synthesis and the source of energy in aerobic catabolism. In marine fish, embryo and larvae FAA are used to maintain body fluid osmolality during fish early development. However, there is essentially no information about FAA concentrations in early ontogeny of freshwater neotropical species in comparison to marine fishes. Therefore, the aim of this study was to evaluate the FAA concentrations in pacu, Piaractus mesopotamicus, eggs and larvae. Broodstock fish were induced to spawn and ovulated females were stripped of their eggs and immediately sampled for analysis. Larvae were sampled right after hatching (HL) and after the completion of the yolk-sac absorption (YSA). The wet weight of the HL and YSA larvae amounted to 0.5±0.1mg and 1.1±0.3mg, respectively. HL larvae showed higher levels of most of the indispensable amino acids (IAA) in comparison to eggs and YSA larvae. Exceptions were observed with His and Trp that showed higher or similar levels, respectively, in YSA larvae. The FAA Orn, Tau, Glu, Gln, Gly, and Tyr increased concentrations in both larval stages while that of Tau was found in higher concentration in all analyzed stages. Also, the concentrations of Asn, Ala, Pro, Ser, and Asp were higher in HL larvae. Both larval stages displayed a rise in total free IAA/total free DAA (dispensable amino acids) ratio. The authors conclude that the highest level of FAA in HL pacu larvae is indicative of active proteolysis of yolk reserves and a probable catabolism regulation of some FAA through spare-effect. In addition, Tau is one of the major FAA occurring during pacu ontogeny and may be performing regulation on body fluid osmolality regulation. © Copyright by the World Aquaculture Society 2013.

Metabolomics method to comprehensively analyze amino acids in different domains

Amino acids play essential roles in both metabolism and the proteome. Many studies have profiled free amino acids (FAAs) or proteins; however, few have connected the measurement of FAA with individual amino acids in the proteome. In this study, we developed a metabolomics method to comprehensively analyze amino acids in different domains, using two examples of different sample types and disease models. We first examined the responses of FAAs and insoluble-proteome amino acids (IPAAs) to the Myc oncogene in Tet21N human neuroblastoma cells. The metabolic and proteomic amino acid profiles were quite different, even under the same Myc condition, and their combination provided a better understanding of the biological status. In addition, amino acids were measured in 3 domains (FAAs, free and soluble-proteome amino acids (FSPAAs), and IPAAs) to study changes in serum amino acid profiles related to colon cancer. A penalized logistic regression model based on the amino acids from the three domains had better sensitivity and specificity than that from each individual domain. To the best of our knowledge, this is the first study to perform a combined analysis of amino acids in different domains, and indicates the useful biological information available from a metabolomics analysis of the protein pellet. This study lays the foundation for further quantitative tracking of the distribution of amino acids in different domains, with opportunities for better diagnosis and mechanistic studies of various diseases.

Free- and peptide-based dietary arginine supplementation for the South American fish pacu (Piaractus mesopotamicus)

Arginine was hypothesized to be a model compound in the present study on molecular forms of indispensable amino acid (IAA) dietary supplementation. Juvenile South American pacu (Piaractus mesopotamicus) were fed diets containing arginine in a protein base (casein-wheat gluten or casein-gelatin), or the casein-wheat gluten base supplemented with dipeptide or free arginine at two levels (5 and 10 g kg(-1)). Growth and protein efficiency ratios were significantly affected by diets, but not by arginine molecular form. Three free dispensable amino acids (DAA) and four IAA in plasma were affected by diet, but plasma arginine concentrations did not differ. Plasma urea concentrations, being very low in the pacu, and hepatic arginase activities, were not affected by diet (P = 0.10-0.11), but together with plasma ornithine, mirrored the growth data. Molecular form of arginine supplementation, free or dipeptide, significantly changed several free IAA (Phe, Leu, Ile, His) and urea, with a higher mean plasma concentration in dipeptide fed fish. The dietary treatments, or molecular form of the arginine supplementation, did not change proximate composition, except that calcium levels decreased with higher dietary arginine supplementation level. The present study indicates that dipeptides can provide IAA to pacu, and that arginine supplemented in this form is utilized as efficiently as in free form.

Sunflower meal in commercial layer diets formulated on total and digestible amino acids basis

An experiment was conduced to evaluate the inclusion of sunflower meal (SBM) in commercial layer diets formulated on total or digestible amino acids basis. One hundred forty-four 41-week-old Lohmann LSL layers were distributed in a completely randomized experimental design in a 2 x 4 factorial arrangement with three replications of six birds each. Treatments consisted of a combination of four SBM inclusion levels SBM(0%, 4%, 8%, and 12%) and feed formulation according two amino acid recommendations (total or digestible). The experimental period was divided into five periods of fourteen days. Performance parameters (egg production, feed intake, feed conversion, egg mass) were evaluated for each period. In the last two days of each period, three eggs per replication were collected to evaluate egg quality (Haugh units, specific gravity, egg weight, eggshell thickness, and eggshell percentage). Hens fed on total amino acid recommendation presented the highest values for egg weight. Diets formulated on digestible amino acids basis showed an improvement in eggshell percentage and egg specific gravity. SBM addition in commercial layer diets did not influence performance; however, increasing SBM dietary levels SBM improved eggshell quality.

Commercial laying hen diets formulated according to different recommendations of total and digestible amino acids

An experiment was conducted to evaluate different commercial laying hen diets formulated based on recommendations for total and digestible amino acids. One hundred and twenty Lohmann LSL commercial laying hens aged 25 weeks were distributed in a completely randomized experimental design involving five replications of six birds in four treatments. Diet formulation on a total amino acid basis followed the recommendations of NRC (1994) and Rostagno et al. (2000), whereas formulation on digestible amino acids basis was according to Rostagno et al. (2000) and Degussa (1997) recommendations. The experimental period was divided into five periods of fourteen days. Performance parameters (egg production, feed intake, feed conversion, egg mass) were evaluated for each period, and on the last two days of each period, three eggs per replication were collected to evaluate egg quality parameters (Haugh unit, egg specific gravity, egg weight, eggshell thickness and percentage). Means were compared by orthogonal contrasts. Results on feed intake, egg production, egg mass, feed conversion and egg specific gravity showed that total amino acid recommendations promoted better bird responses than digestible amino acid recommendations.

Synthesis of potentially bioactive PABA-related N-(aminoalkyl)lactamic amino acids and esters via selective SNAr reactions

Potentially bioactive N-(aminoalkyl)lactamic amino acids and esters were synthesized in satisfactory to good yields by SNAr reactions of aromatic acids with N-(3-aminopropyl)lactams followed by esterification with tertiary amino alcohols. The addition-elimination SNAr mechanism was confirmed by NMR and MS measurements.

Mechanisms of insulin secretion in malnutrition: modulation by amino acids in rodent models

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Photoacoustic spectroscopy of aromatic amino acids in proteins

This paper concerns the use of photoacoustic spectroscopy (PAS) to study the presence of aromatic amino acid in proteins. We examined the aromatic amino acids in six proteins with well-known structures using absorption spectra of near ultraviolet PAS over the wavelength range 240-320 nm. The fundamental understanding of the physical and chemical properties that govern the absorption of light and a subsequent release of heat to generate a transient pressure wave was used to test the concept of monitoring aromatic amino acids with this method. Second derivative spectroscopy in the ultraviolet region of proteins was also used to study the regions surrounding the aromatics and the percentage area in each band was related in order to determine the contribution in function of the respective molar extinction coefficients for each residue. Further investigation was conducted into the interaction between sodium dodecyl sulphate (SDS) and bothropstoxin-I (BthTx-I), with the purpose of identifying the aromatics that participate in the interaction. The clear changes in the second derivative and curve-fitting procedures suggest that initial SDS binding to the tryptophan located in the dimer interface and above 10 SDS an increased intensity between 260 and 320 nm, demonstrating that the more widespread tyrosine and phenylalanine residues contribute to the SDS/BthTx-I interactions. These results demonstrate the potential of near UV-PAS for the investigation of membrane proteins/detergent complexes in which light scattering is significant.

The activity of amino acids produced by Paenibacillus macerans and from commercial sources against the root-knot nematode Meloidogyne exigua

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Electrochemical behavior of the N-nosyl-protected amino acids in N,N-dimethylformamide

The electrochemical reduction of serine, glycine, and leucine protected by the 4-nitrobenzenesulfonyl, group in N,N-dimethylformamide at mercury cathode occurs at two steps. The first one at -0.8 V vs. SCE, after a one-electron transfer, leads the anion radical formation that dimerizes and adsorbs at electrode. In the second step at -1.4 V, an instable dianion forms which then cleaves. The mechanism is discussed.