Leucine, Not Total Protein, Content of a Supplement Is the Primary Determinant of Muscle Protein Anabolic Responses in Healthy Older Women.

Background: Older adults show a blunted muscle protein synthesis (MPS) response to postprandial hyperaminoacidemia relative to younger adults. Evidence suggests that this anabolic resistance can be overcome by consuming greater quantities of leucine. Objective: The purpose of this trial was to determine whether the addition of leucine to a smaller dose (10 g) of milk proteins would, when compared with a larger dose (25 g) of whey protein isolate (WPI), result in similar increases in acute (hourly) and integrated (daily) myofibrillar protein synthesis (myoPS). Methods: Healthy older (mean ± SD age: 69 ± 1 y) women (n = 11/group) were randomly assigned with the use of a single-blind, parallel-group design to twice-daily consumption of either WPI [25 g WPI (3 g l-leucine)] or leucine (LEU; 10 g milk protein with 3 g total l-leucine) for 6 d. Participants performed unilateral resistance exercise to allow assessment of the impact of the supplement alone and with resistance exercise. We determined acute (13C6-phenylanine) and integrated [using deuterated water (D2O)] rates of myoPS in the fasting (acute), basal (integrated), nonexercised, and exercised states. Results: Acute myoPS increased in both legs in response to LEU (fed: 45%; fed+exercise: 71%; P < 0.001) and WPI (fed: 29%; fed+exercise: 47%; P < 0.001) compared with fasting; the increase was greater with LEU than with WPI in the exercised leg (46%; P = 0.04) but not in the rested leg (P = 0.07). The acute myoPS response was greater in the exercised leg than in the rested leg for both WPI (63%) and LEU (58%) (P < 0.001). Integrated myoPS increased with WPI and LEU in the exercised leg (both 9%; P < 0.001) during supplementation, and with WPI (3%; P = 0.02) but not LEU (2%, P = 0.1) in the rested leg compared with the basal state. Conclusions: A lower-protein (10 compared with 25 g/dose), leucine-matched beverage induced similar increases in acute and integrated myoPS in healthy older women. Lower-protein supplements with added leucine may represent an advantageous approach in older adults to maintain skeletal muscle anabolic sensitivity and attenuate muscle loss; however, further work is needed using longer-term interventions to substantiate these findings. This trial was registered at www.clinicaltrials.gov as NCT02282566.

Capability of in vitro digestibility methods to predict in vivo digestibility of vegetal and animal proteins

The purpose of this work was to establish predictive equations for the digestibility of proteins of animal and vegetal origin by correlating in vitro and in vivo methods. Proteins sources for animal and vegetable were used. To calculate in vitro digestibility, we used pH values obtained 10 min after a solution of enzymes was added to a protein solution (pH-drop method). We also used the pH-static method, which measures the volume of additional NaOH that is necessary to maintain a pH of 8.0 after the addition of an enzymatic solution. In vivo digestibility was measured in newly weaned male rats that were fed a diet of AIN-93G for growth with a modified protein content of 9.5% for 14 days. The equations developed using the pH-drop method allowed us to predict in vivo digestibility amounts that were more closely correlated with real in vivo digestibility than those obtained with equations using the pH-static method. In vitro techniques are less expensive, require less manpower and physical space, and use a smaller quantity of protein(AU)

O objetivo deste trabalho foi estabelecer equações de predição para a digestibilidade das proteínas de origem animal e vegetal, correlacionando métodos in vitro e in vivo. Foram utilizadas proteínas de origem animal e vegetal. Para o cálculo da digestibilidade in vitro foram utilizados os valores de pH obtidos em 10 min após a adição da solução de enzimas (método de queda de pH). Também foi utilizado o método de pH estático, o qual mede o volume de NaOH adicionado, necessário para manter o pH em 8,0 após a adição de uma solução enzimática. A digestibilidade in vivo foi medida em ratos machos recémdesmamados que foram alimentados com uma dieta AIN- 93G para crescimento com teor de proteína modificada de 9,5% durante 14 dias. As equações desenvolvidas utilizando o método de queda de pH permitiram prever em quantidades digestibilidade in vitro que foram mais estreitamente correlacionadas com a digestibilidade in vivo do que aqueles obtidas utilizando equações do método de pH estático. As técnicas in vitro são menos dispendiosas, exigem menos mão-de-obra e espaço físico, e utiliza uma menor quantidade de proteína(AU)

From Lab Bench To Kitchen Table.

As the environmental impact of large-scale animal farming increasingly threatens global health, the hunt is on for new sources of protein.

Optimization of wastewater feeding for single-cell protein production in an anaerobic wastewater treatment process utilizing purple non-sulfur bacteria in mixed culture condition.

Impacts of operation timing of feeding and withdrawal on anaerobic wastewater treatment utilizing purple non-sulfur bacteria have been investigated in mixed culture condition with acidogenic bacteria. Simulated wastewater containing glucose was treated in a laboratory-scale chemostat reactor, changing the timing of wastewater feeding and withdrawal. Rhodopseudomonas palustris, which does not utilize glucose as a substrate, was inoculated in the reactor. Rps. palustris was detected by a fluorescent in situ hybridization (FISH) technique using the specific Rpal686 probe. As a result, population ratios of Rps. palustris were over 20% through the operation. Rps. palustris could grow by utilizing metabolites of acidogenic bacteria that coexisted in the reactor. A morning feed was effective for a good growth of purple non-sulfur bacteria. A protein content of cultured bacteria was the highest when wastewater was fed in the morning. Dissolved organic carbon (DOC) removal was 94% independent of the timing control. Consequently, feeding in the morning is the optimum feed-timing control from the aspects of growth of purple non-sulfur bacteria and single-cell protein production.

Creating proteins with novel functionality via the Maillard reaction: a review.

Proteins are widely utilized to add functional properties, such as gelling and emulsification to foods. These attributes depend on a number of factors such as molecular structure of the protein, the pH, and the composition of its chemical environment. There is substantial evidence to suggest that the functional properties of food proteins can be further improved by derivatization. Covalent bonding of proteins to polysaccharides and smaller reducing sugars via the Maillard reaction has been shown to alter the functionality of proteins without requiring the addition of chemical reagents. Establishment of a technologically feasible method for preparing the conjugates and optimization of the processing conditions, however, is needed to promote their development as functional food ingredients. This paper provides a state-of-the-art contribution to the impact of the Maillard reaction on protein functionality. It presents a deeper understanding of the influence of processing conditions and reactant formulation on improving desirable properties of proteins. In particular attention is given to how potential improvements could be achieved in the emulsifying, textural, and solubility properties of proteins to add value to commodity food ingredients. Elements that are considered to be critical to the design of functional Maillard conjugates are highlighted and suggestions proposed to facilitate progress in this area.

A consensus residue analysis of loop and helix-capping residues in four-alpha-helical-bundle proteins.

A statistical study was performed on a set of proteins which adopt the four-alpha-helical-bundle tertiary motif in order to determine amino acid occurrences at helix-capping and loop positions. Eight X-ray crystal structures from the Brookhaven Protein Data Bank (PDB) were examined and N", N', Ncap, Ccap, C' and C" residues were assigned. In addition, a set of 55 protein sequences for the analogous proteins from different strains and species was taken from the Protein Information Resource and Swiss-Prot databanks. The residues at the capping and loop positions in this expanded data set were deduced by aligning these sequences with those from the PDB files. Similar trends were observed in the two data sets. In general, polar residues were predominant in the loops, although aromatic residues were also fairly common. Glycine, a highly flexible residue with an excellent 'helix-breaking' ability, was very common at the Ccap, C' and C" residues. Proline, which can force sharp turns in the direction of a peptide backbone, was only common at the N" residue. Residues which can participate in the N-capping box motif were found with high frequency. Capping motifs at the helix C-termini (Schellman and alphaL motifs) were also somewhat common, while another helix N-terminal stabilizing motif, the hydrophobic stable, was not common. The data presented in this study should prove useful for applying the 'consensus residue' approach to the de novo design of loop regions in helical bundle proteins.

Prediction of folding stability and degradability of the de novo designed protein MB-1 in cow rumen.

The authors have recently reported on the design of a protein (MB-1) enriched in methionine, threonine, lysine, and leucine. The protein is intended to be produced by rumen bacteria, in a way that would provide high producing lactating cows with limiting amino acids. In this report, MB-1 stability in the rumen is assessed, i.e., where the protein might be found after cell lysis or after being secreted by rumen bacteria. Current in vitro methods used to predict proteolytic degradability in the rumen were used for MB-1, as well as other natural proteins for comparison. MB-1 was found to be more susceptible to degradation than cytochrome c and ribonuclease A. Data indicate that MB-1 will be rapidly degraded if exposed to the rumen environment without protection. The contribution of folding stability to proteolytic stability was also examined. Rumen liquor components were selected to formulate a solution compatible with constraints of thermal denaturation studies. Denaturation curves show that the natural proteins were folded at rumen temperature. The MB-1 denaturation curves indicated that MB-1 does not unfold in a cooperative transition when heated from 20 to 70 degrees C. This suggests that MB-1 structure may be progressively modified as temperature increases, and that a continuum of conformations are available to MB-1. At 39 degrees C, a significant (50%) portion of MB-1 molecules had their tertiary structure unfolded, contributing to proteolytic degradability. Despite the unusual constraints used in MB-1 design (i.e., a maximized content in selected essential amino acids), results show that MB-1 has structural properties similar to previously reported de novo designed proteins.