Energy Cost Of Protein Synthesis Research Articles

Evaluation of the Arteriovenous Difference Technique to Simultaneously Estimate Protein Synthesis and Degradation in the Hindlimb of Fed and Chronically Underfed Steers

Our objectives were to validate a technique to measure protein turnover based on net fluxes of tyrosine radioactivity and mass across the hindlimb, and to describe the impact of nutrition on hindlimb protein kinetics and nutrient utilization in growing Holstein steers. External iliac vessels were catheterized to allow for measurements of hindlimb arteriovenous (AV) differences and blood flow. Animals were used in a single reversal design with 16-d periods. Treatments were either 60% (0.6M) or 220% (2.2M) of the energy required for maintenance. On d 12 and 14 of each period, a primed-continuous infusion of L-[side chain-2,3-3H]tyrosine was initiated, followed by a 4-h sampling period to assess hindlimb nutrient utilization and protein kinetics. Well-fed steers exhibited rates of hindlimb utilization for non-nitrogenous energy substrates and amino acids that were consistent with values previously reported for well-fed ruminants. Underfeeding decreased hindlimb blood flow (62%), oxygen consumption (51%) and utilization of respiratory fuels (64-73%). Protein synthesis was also reduced (49%), leading to net nitrogen loss from the hindlimb. The estimated energy cost of protein synthesis accounted for 13% of hindlimb oxygen consumption across intake levels. Hindlimb protein balance was consistent with whole-body balance, adding credence to derived rates of degradation. Overall, data support the validity of the AV difference technique to estimate components of hindlimb protein turnover.

Noise in gene expression may be a choice of cellular system

Gene expression and its regulation is a nonequilibrium stochastic process. Different molecules are involved in several biochemical steps in this process with low copies. It is observed that the stochasticity in biochemical processes is mainly due to the low copy number of the molecules present in the system. Several studies also show that the nonequilibrium biochemical processes require energy cost. But cellular system has developed itself through natural evolution by minimizing energy cost for optimum output. Here, we study the role of stochasticity qualitatively in a network of two genes using stochastic simulation method and approximately measure the energy consumption for the gene expression process. We find that the noise in gene expression process reduces the energy cost of protein synthesis. Therefore, we argued that the stochasticity in gene expression may be a choice of cellular system for protein synthesis with minimum energy cost.

About the Cover

Next article FreeAbout the CoverPDFPDF PLUSFull Text Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinked InRedditEmailQR Code SectionsMoreCoverThe Pacific oyster (Crassostrea gigas) is found along the coasts of all continents except for Antarctica. This species ranks among the world's highest production for marine aquacultured animals, and has emerged as a sentinel for the biological impacts of global ocean acidification. The cover image shows a 10-day-old (~150 μm in shell length) veliger larva of C. gigas, with its velum extended. The velum is the organ used for movement and feeding. A veliger larva swims with the velum upward, but can move in any direction. The small larval stages of this species typify the complex life history of many species of marine invertebrates and fish, and offer tractable experimental systems for study of the physiology of development.Across animal species, values reported for the energy cost per unit mass of protein synthesis vary widely. It remains unknown, however, whether there is genetic variation for this cost within a species. On pages 175–187 of this issue, Lee, Applebaum, and Manahan present experiments conducted with larval families of C. gigas that were produced in crosses of diploid, triploid, and selectively bred pedigreed genetic lines. The authors report that the energy cost of protein synthesis is independent of genotype, growth phenotype, and environmental temperature. Further, they found that the cost of protein synthesis can account for over half of the total metabolic rate of a larva. Knowing the cost of biosynthesis provides a bioenergetic framework for defining energy requirements during larval growth, and for evaluating the potential for metabolic adaptation under different environmental conditions.Credits: Photo, Scott L. Applebaum, University of Southern California; cover design, LianneDunn.com. Next article DetailsFiguresReferencesCited by The Biological Bulletin Volume 230, Number 3June 2016 Published in association with the Marine Biological Laboratory Article DOIhttps://doi.org/10.1086/BBLv230n3cover © 2016 by Marine Biological Laboratory. All rights reserved.PDF download Crossref reports no articles citing this article.

Architecture of a harmonized model of the growing pig for the determination of dietary net energy and protein requirements and of excretions into the environment (IMS Pig)

AbstractThe model incorporates, amongst its novel components, variable efficiency coefficients in the simulation of the responses of growing pigs to nutrient inputs, and thereby increases the accuracy and efficacy of control of feeding and nitrate excretion. The model determines (rather than is presented with) net energy and required amino acid level and balance. The estimation of protein turn-over as a function of rate of protein retention, protein mass and the maturity of the pig was found to be central to both the energy (ATP) and protein economy. Protein turn-over varied from around 0·14 to 0·08 of the protein mass depending upon the size of the pig. Efficiencies of energy yield from lipid, starch (and sugar), protein and (fibre-derived) volatile fatty acids were calculated to be 0·98, 0·86, 0·56 and 0·58 for ATP production and 0·90, 0·70, 0·50, and 0·44 for lipid retention, respectively. The maximum efficiency of use of ileal digestible amino acids was determined as around 0·85. The energy cost of protein synthesis was equivalent to 4·2 MJ metabolizable energy (ME) per kg, and the efficiency of use of ME for protein retention varied from 0·55 to 0·40 depending on the protein mass of the pig. The components of the model and the biochemical drivers are described in detail, and proof of principle of the main elements is presented. The model is different in its architecture to other published simulation models, and is considered to add to the present knowledge base in this discipline.

Factors affecting the respiration/ETS ratio in marine zooplankton

Factors affecting the respiration/ETS ratio in marine zooplankton

Protein Synthesis in Juvenile Tilapia Oreochromis mossambicus

AbstractA method for measuring protein synthesis has been developed for small juvenile fish. A flooding dose of [3H] phenylalanine (Houlihan et al. 1988b) was added to the water containing the animals. Using juvenile tilapia O. mossambicus of approximately 15 mg, stability of the phenylalanine free pool specific radioactivity was achieved within 10 h. A linear increase in the whole body specific radioactivity of protein‐bound phenylalanine occurred 3 h after [3H] phenylalanine was added to the water. In larger animals the flooding dose was injected into the peritoneum, and stable free pool phenylalanine specific radioactivities were achieved over 2 h. In the small fish the rate of protein synthesis exhibited a diurnal pattern. Scaling relationships for growth, protein synthesis and protein degradation were similar. The energy cost of protein synthesis in small juvenile animals, determined from the difference before and after the addition of the protein synthesis inhibitor cycloheximide, was close to the theoretical minimal cost.

TYROSINE FLUX AND BODY PROTEIN SYNTHESIS IN GROWING LAMBS

Body protein synthesis was estimated in lambs after continuous infusion of 3H-tyrosine for 8 h. The specific activity of plasma tyrosine reached a plateau during the last hour of infusion. Mean (± SE) tyrosine flux values were 80.3 ± 8.8 mmol/day. Mean daily rate of protein synthesis was 485.2 ± 53.4 g/day or 8.4 ± 0.5 g∙kg−1∙day−1. Protein synthesis was positively correlated with body weight and the energy cost of protein synthesis was estimated to be 2.2 MJ/day. Key words: Tyrosine flux, protein synthesis, lambs

Increased energy expenditure in poorly controlled Type 1 (insulin-dependent) diabetic patients.

The basal energy expenditure of 10 Type 1 (insulin-dependent) C-peptide-negative diabetic patients (2042 +/- 62 kcal/24 h) was found to be significantly higher than the 1774 +/- 52 kcal/24 h predicted from their age, sex and body surface area (p less than 0.01). Intravenous insulin treatment significantly reduced energy expenditure to 1728 +/- 19 kcal/24h (p less than 0.01), which matched predicted values. The observed increase in metabolic rate in uncontrolled diabetic patients is associated with increased protein turnover, increased plasma glucagon, but no significant increase in cortisol, growth hormone or triiodothyronine concentrations in plasma. It may be accounted for by the energy cost of protein synthesis, or gluconeogenesis, or possibly increased sympathetic activity. This increased energy expenditure will contribute to the weight loss seen in Type 1 diabetic patients.

ENERGY PARTITION OF PROTEIN SYNTHESIS IN RESTING ENERGY EXPENDITURE OF NEONATES ON TPN

To determine the influence of protein turnover on resting metabolic rate of post-surgical infants on TPN, the rate of protein synthesis (S), catabolism (C), net protein gain (PG) and resting energy expenditure (REE) were measured in 11 infants, birthweight 2340±172g(SEM), gestational age 37±0.9wk. Study weight was 2445±204g on postnatal day 17±3. Energy intake was 89.1±3.4kcal/kg/d; protein intake was 3.2±0.2g/kg/d. S and C were calculated from the plateau of urinary 15N enrichment reached during 72h of 15N glycine infusion. Infusion was started at least 3 days after surgery. PG was calculated as net synthesis (S-C) while REE was measured by open circuit indirect calorimetry. Results are as shown.There was a significant correlation between REE and PG (r=0.72, p<0.01). The slope indicated an expenditure of 11 kcal/g PG. An average of 5.5g protein was synthesized per g PG. The energy cost was 2.0kcal/g(S). The energy expenditure was 19.8 kcal to synthesize 9.89g protein. Since all energy produced during protein breakdown is released as heat we conclude that about 44.5% of resting energy expenditure can be accounted for as the energy cost of protein synthesis in post-surgery infants.

Nutrition and protein turnover in man.

The healthy young adult synthesizes and degrades at least 200 g of tissue protein each day (Waterlow et al., 1978a). By comparison, the dietary intake of protein is typically only one-third of this value. Measurements in man and in a number of other species have shown that there is an approximate parallelism between the rate of protein turnover by the whole body and a number of other metabolic parameters, such as the requirement for dietary protein (Young et al., 1975) and basal energy expenditure (Munro, 1964; Waterlow, 1968). Indeed, the expenditure of metabolic energy is required for the formation of peptide bonds; at a conservative estimate, the energy cost of protein synthesis accounts for 20% of oxygen consumption.

Protein synthesis in tissues of growing lambs.

1. The fractional rate of protein synthesis (FSR) in tissues of nine growing lambs (4-5 months of age) was estimated following continuous infusion of L-[4,5-3H]leucine for a period of 7 h. Minimum and upper estimates of FSR were obtained assuming that the specific radioactivity (SRA) of leucine in blood plasma and tissue homogenate respectively defined that of leucyl tRNA. 2. Mean upper estimates of tissue protein FSR (/d) were skin 0.35, longissimus dorsi muscle 0.05 biceps femoris muscle 0.04, liver 0.54, rumen 0.79, cardiac muscle 0.09. Minimum estimates of tissue protein FSR ranged from 0.03 (muscle) to 0.15 (liver). 3. Plasma leucine flux was closely related to body protein content and dietary leucine absorption (r 0.94). 4. The rate of whole-body protein synthesis (WBS) derived from plasma leucine flux corrected for oxidation and localized recycling of leucine into protein was similar to that calculated from the sum of daily protein synthesis in individual tissues using the upper estimate of FSR, i.e. 610 g/d v. 581 g/d. 5. The estimate of WBS derived from plasma leucine flux directly (241 g/d) was similar to that calculated from the sum of minimum estimates of daily protein synthesis in individual tissues (214 g/d). 6. The ratio, intracellular leucine SRA:plasma leucine SRA tended to increase with increasing dietary leucine absorption in all tissues although these factors were only significantly correlated (P less than 0.05) in cardiac muscle, skin and rumen. Such relationships suggest an increased exchange of plasma leucine with intracellular leucine with increased food intake. 7. It was estimated that the energy cost of protein synthesis accounted for approximately 42% of daily heat production.

Whole body and tissue protein synthesis in cattle.

1. The daily rates of synthesis of protein by the whole body and by the individual tissues were determined in two Hereford x Friesian heifers (236 kg and 263 kg live weight), and a dry Friesian cow (628 kg live weight). 2. The rate of whole-body protein synthesis (g protein/d) was estimated from the total flux through the blood of [3H]leucine and [3H]tyrosine following infusion at a constant rate for 8 h. 3. The fractional rates of protein synthesis (ks) in the tissues (g synthesized/d per g tissue protein) were obtained after slaughter of the animals at the end of the infusion period. The fractional rate of protein synthesis was calculated assuming that the specific radioactivity of free tyrosine in either the blood (to give ks, b) or the tissue homogenate (to give ks, h) defined closely the specific radioactivity of the amino acid precursor for protein synthesis. total protein synthesis (As, b or As, h; g/d) in an individual tissue was calculated as the product of ks, b (or ks, h) x protein content. 4. Based on the total leucine flux, i.e. without correction for oxidation, 1.6 kg protein were synthesized daily in the heifers; for the cow this value was 2.0 kg/d. 5. The sum of the daily total synthesis in the major tissues (muscle+bone+brain, gastrointestinal tract (GIT), liver, hide) gave values of 1.4-1.9 kg/d based on As, b, and 2.2-3.0 kg/d based on As, h. 6. percentage contributions of the individual tissues to the total protein synthesis were similar in all three animals, for example based on As, h muscle was 12-16; carcass (muscle+bone+brain) 32-33; GIT 38-46; liver 7-8; skin 14.21%. 7. The contribution of muscle to total synthesis estimated from the leucine flux was 19-22%; this value is in agreement with those calculated on the same basis for other species. 8. The energy cost of protein synthesis was estimated to account for a maximum of 30% of heat production.

Increased rates of whole body protein synthesis and breakdown in children recovering from burns.

The rates of whole body protein synthesis and breakdown were determined, with the aid of a constant administration of [15N]glycine, during recovery in 11 acutely burned children, involving a total of 24 studies. Eleven studies were also conducted in seven healthy children before and after reconstructive surgery. Rates of whole body protein synthesis and breakdown, expressed as g protein/kg body weight/day, were significantly (p less than 0.05) and positiviely correlated with per cent body surface area total burn, per cent third-degree burn, and per cent open wound. These rates (synthesis, 7.1 +/- 2.1 g protein/kg/day; breakdown, 6.3 +/- 1.8 g protein/kg/day) were 80 to 100% greater (p less than 0.05) in patients with total burns greater than or equal to 60%, as compared to patients with less than 25% total burns or to the surgical patients. Because of the high energy cost of protein synthesis, it is proposed that an increased whole body protein turnover is partly responsible for the reported elevations in rates of heat production occurring in patients recovering from thermal injury.

Effect of Environmental Temperature on Utilization of Dietary Protein by the Growing Rat

It has been shown that, provided the energy intakes of animals are below a certain physiological maximum, the thermogenesis resulting from cold exposure is accompanied by an increased food consumption, and an improved growth and N balance as compared with animals at thermal neutrality. Under these conditions, efficiency of protein utilization, rate of total endogenous N loss, and the energy cost of protein synthesis were shown to be unchanged. When the temperature, and dietary regimen were such that the animal's maximum food intake was inadequate to meet its energy needs for growth and thermogenesis, the efficiency of protein utilization was reduced as compared with that at normal temperatures, in a manner analogous to the reduction observed at restricted caloric intakes. Equations are presented, for prediction of effective protein values of diets under conditions of caloric restriction and reduced temperature. The significance of these observations is discussed in relation to the optimal conditions for efficient feeding of livestock, and also the standardization of conditions under which measurements of protein quality should be made.