The Mitochondrial Ribosome Associated Protein Quality Control System and Diseases / 中国生物化学与分子生物学报

Protein synthesis is a complex process. Under certain circumstances, abnormal ribosome stalling will occur during translation, resulting in the inability to effectively recover the ribosome for the next round of translation. Nascent polypeptides arisen from the stalled ribosome are at risk of forming aggregate species, and disturbing protein homeostasis and contributing to development of diseases. The ribosome-associated protein quality control(RQC) pathway provides a rescue method for recovering of stalled ribosomes and for proteasomal degradation of nascent polypeptides obstructed on 60S subunits. The latest researches show that there are RQC rescue pathways on the surface of mitochondria (called mitochondrial ribosome-associated protein quality control, mitoRQC). Mitochondria are important organelles involved in energy production and metabolism in eukaryotic cells. More than 98% of mitochondrial proteins are encoded by nuclear genes and transported from the cytoplasm to mitochondria. These proteins are potential targets for mitoRQC, which works synergistically with the internal regulation system of mitochondria to maintain mitochondrial stability. In this review, we will focus on the recent progress on the RQC and mitoRQC pathway as well as their implications in the progression of diseases.

Evaluation of the biological quality of defatted pequi (Caryocar brasiliense Cambess) seed flour protein supplemented with lysine to rats (Rattus norvegicus) / Avaliação da qualidade biológica da proteína da farinha da semente do pequi (Caryocar brasiliense Cambess) desengordurada e suplementada com lisina em ratos (Rattus norvegicus)

ABSTRACT Objective In the biome of the Brazilian Cerrado, there are a lot of fruit tree species that stand out for their sensory quality and for presenting potentialities in the market of pulp and almond. Among these species, the pequi deserves attention because it has an almond rich in proteins and that is little explored. The aim of this study was to evaluate the biological quality of defatted pequi seed flour supplemented with lysine. Methods Two designs were done in this study; in the first, the animals were divided into four diet groups: control, protein-free, defatted pequi seed flour and defatted pequi seed flour supplemented with lysine. The protein-free diet was exempt of proteins and the other diets had a protein content of 10% and differed in protein source (casein: control diet or defatted pequi seed flour: test diets). The experiment lasted for 14 days. In the second design, 36 animals were used and followed-up for 28 days. The division of the experimental groups was kept, except for the protein-free diet group, which was excluded. By the end of the test, the animals were anaesthetised and euthanized. Results The results showed that the protein efficiency ratio of the control group was significantly higher than the other groups. For the other indices, the groups that received defatted pequi seed flour did not differ statistically among themselves. Conclusion These findings have shown an effect of supplementation on the protein efficiency ratio when comparing the test diets, however, when compared to the control group, no improvement was found.

RESUMO Objetivo O bioma cerrado é rico em espécies frutíferas que destacam-se por suas qualidades sensoriais e por apresentarem potencialidades no mercado de polpas e amêndoas. Dentre essas espécies, o pequi merece atenção porque possui uma amêndoa rica em proteínas e que é pouco explorada. Este estudo teve como objetivo avaliar a qualidade biológica da farinha da semente do pequi desengordurada e suplementada com lisina. Métodos Neste estudo foram feitos dois delineamentos: no primeiro os animais foram divididos em quatro grupos: controle, aprotéico, farinha da semente do pequi desengordurada e farinha da semente do pequi desengordurada suplementada com lisina. A dieta aprotéica era isenta de proteínas e as demais dietas apresentavam um teor de 10% de proteínas e diferiram quanto à fonte protéica (caseína: dieta controle e farinha da semente do pequi desengordurada: dietas testes). Esse experimento teve duração de 14 dias. No segundo delineamento, utilizou-se 36 animais que foram acompanhados por 28 dias, a divisão dos grupos experimentais foi mantida, exceto o grupo dieta aprotéica que foi excluído. Ao final dos experimentos, os animais foram anestesiados e eutanasiados. Resultados Os resultados mostraram que o coeficiente de eficiência protéica do grupo controle foi significativamente superior aos demais grupos. Para os demais índices biológicos de avaliação da qualidade protéica, os grupos que receberam a farinha da semente do pequi desengordurada não diferiram estatisticamente entre si. Conclusão Os achados mostraram um efeito da suplementação no coeficiente de eficiência protéica quando comparamos as dietas testes, no entanto, quando comparado ao grupo controle, não houve melhora.

Effect of different pre-boiling treatment on in vitro protein and amino acid digestibility of mung beans [Vigna radiata (L.) Wilczek]

@#Introduction: Mung beans [Vigna radiata (L.) Wilczek] are good sources of protein. Nevertheless, its protein quality is still questionable. This study aimed to determine the effect of different processes prior to boiling, on the in vitro protein and amino acid digestibility of mung beans by using a 6-hour enzymatic digestion. Methods: This study was based on the household method of the processes before boiling including unsoaking, soaking, and dehulling. Products from all treatment methods were analysed for proximate composition (moisture, crude protein, crude fat, ash, and dietary fibre) on a dry basis, naturally occurring anti-nutritional factors, amino acid composition, and digestibility of protein and amino acids. The amino acid composition and amino acid digestibility were used to calculate the dietary protein quality. Results: The treatments prior to the boiling of mung beans such as dehulling, soaking and without soaking, improved protein digestibility significantly by 10.8%, 10.3%, and 12.0%, respectively, when compared with that of raw mung beans (37.9%). Of the different mung bean pre-treatments, soaking seems to have the highest value of average indispensable amino acid (IAA) digestibility (55.4%), in particularly branched-chain amino acids (66.4%). However, there was no difference in the protein quality in terms of digestible indispensable amino acid score (DIAAS) across different treatment groups. Conclusion: The different processes performed on mung bean before boiling had only a slight impact on its amino acid digestibility and they rarely affected DIAAS values.

Protein quality & amino acid requirements in relation to needs in India

The relevance of protein and its constituent amino acids (AAs) in the structure and function of the human body is well known. Accumulating evidence has conferred specific functional and regulatory roles for individual AAs, adding relevance to their requirements across different age groups. The methods for measuring AA requirements have progressed from the classical nitrogen balance to the current stable isotope-based AA balance methods. Requirements of most of the indispensable AA (IAA) have been estimated in healthy Indian population by the best available balance method and has shown to be higher than earlier 1985 WHO/FAO/UNU (World Health Organization/Food and Agriculture Organization/United Nations University) recommendations. In addition, potential changes in the requirement, through adaptation to chronic undernutrition or to infection, have also been evaluated. In 2007, the WHO/FAO/UNU released a recommendation that increased the daily IAA requirement, based on primary evidence from Indian balance studies. This meant that to ensure that the new IAA requirements were met, individual foods or mixed diets needed to be assessed for their protein quality, or their ability to deliver the required amount of IAA. The recent FAO report on protein quality evaluation recommends the use of a new chemical AA score, the digestible IAA score (DIAAS), to replace the earlier protein digestibility corrected AA score. The DIAAS requires the determination of individual AA digestibility at the ileal level. A minimally invasive dual stable isotope tracer-based approach has been developed in India and has been used to determine digestibility of various foods in Indian adults and children. The increase in IAA requirements and subsequent protein quality requirements have implications for national regulatory frameworks, growth and development, and in turn, for economic and agricultural policy.

Calidad proteica de la dieta en lactantes con desnutrición severa / Protein quality in the diet of infants with severe malnutrition

Introducción: la desnutrición severa infantil constituye un problema vigente en países pobres, porque los requerimientos nutrimentales se proporcionan de manera inadecuada. Las necesidades proteicas relacionadas con la tasa de crecimiento, se reflejan en la cantidad requerida de aminoácidos esenciales; del total de proteínas, la dieta de adultos debe contener 15 por ciento, y la de lactantes entre 33 y 37 por ciento de estos aminoácidos. La calidad proteica se obtiene calculando el escore de aminoácidos, a partir del cual se diseñó el patrón seguro para diferentes grupos de edades, que incluye composición en aminoácidos esenciales, sus proporciones y digestibilidad, y es adecuada cuando estas proporciones satisfacen los requerimientos de nitrógeno para crecimiento, síntesis, y reparación tisular. Objetivos: determinar la calidad proteica de la dieta de lactantes con desnutrición severa, ingresados en el Hospital Francisco Icaza Bustamante de Guayaquil, Ecuador, durante el periodo 2009-2010; y los específicos, diagnosticar el tipo de desnutrición severa de los pacientes, identificar el perfil de aminoácidos en la dieta de los casos de estudio, así como establecer el valor biológico de las proteínas dietéticas que reciben. Métodos: estudio de enfoque cuantitativo, observacional, descriptivo, analítico y de corte transversal, en lactantes con diagnóstico de desnutrición severa. La población incluyó a todos los pacientes con desnutrición severa, menores de 24 meses de edad; la muestra fue de 33 pacientes, basada en criterios de selección. Para evaluar calidad proteica se utilizó el Escore de Aminoácidos Corregido por Digestibilidad Proteica, comparando el perfil dietético con las necesidades del niño(AU)

Introduction: severe childhood malnutrition is a current health problem in poor countries because nutritional requirements are inadequately met. Protein needs related to growth rates are reflected in the volume required of essential amino acids. Of the total proteins, the diet of adults should contain 15 percent and that of infants between 33 and 37 percent of these amino acids. Protein quality was obtained by estimating the score of amino acids, starting from which a safe pattern was designed for different age groups, including the composition as to essential amino acids, their proportions and digestibility. It is considered to be adequate when these proportions meet the nitrogen requirements for growth, synthesis and tissue repair. Objectives: determine the protein quality of the diet of infants with severe malnutrition staying at Francisco Icaza Bustamante hospital in Guayaquil, Ecuador, during the period 2009-2010. Specific objectives are to diagnose the type of severe malnutrition of patients, identify the amino acid profile in the diet of the study cases, and establish the biological value of the diet proteins they receive. Methods: a quantitative cross-sectional analytical descriptive observational study was conducted of infants diagnosed with severe malnutrition. The study population included all the patients with severe malnutrition aged under 24 months. The sample was 33 patients, based on selection criteria. Protein quality was evaluated with the Protein Digestibility Corrected Amino Acid Score, comparing the dietary profile with the needs of the child. Results: statistical analysis showed that all patients had several limiting amino acids in their diet. Conclusions: the diet of infants with severe malnutrition has a poor protein quality, with an amino acid coefficient inadequate for synthesis functions and the consequent negative impact on growth and development(AU)

Protein quality, hematological properties and nutritional status of albino rats fed complementary foods with fermented popcorn, African locust bean, and bambara groundnut flour blends

The objective of this study was to determine protein quality and hematological properties of infant diets formulated from local food materials. The food materials were obtained locally, fermented, and milled into flour. The flours were mixed as 70% popcorn and 30% African locust bean (FPA), 70% popcorn and 30% bambara groundnut (FPB), and 70% popcorn, 20% bambara groundnut, and 10% African locust bean (FPAB). Proximate analysis, protein quality, hematological properties, and anthropometric measurements of the animals fed with the formulations were investigated. The protein contents of the formulated diets were significantly higher than that of Cerelac (a commercial preparation) (15.75 +/- 0.01 g/100 g) and ogi (traditional complementary food) (6.52 +/- 0.31 g/100 g). The energy value of FPAB (464.94 +/- 1.22 kcal) was higher than those of FPA (441.41 +/- 3.05 kcal) and FPB (441.48 +/- 3.05 kcal). The biological value (BV) of FPAB (60.20%) was the highest followed by FPB (44.24%) and FPA (41.15%); however, BV of the diets was higher than that of ogi (10.03%) but lower than that of Cerelac (70.43%). Net protein utilization (NPU) of the formulations was 41.16-60.20%, whereas true protein digestibility was 41.05-60.05%. Metabolizable energy (232.98 kcal) and digestible energy (83.69 kcal) of FPAB were the highest, whereas that of FPA had the lowest values. The protein digestibility values corrected for amino acid score of the diets (0.22-0.44) were lower than that of Cerelac (0.52), but higher than that of ogi (0.21). The growth patterns and hematological properties (packed cell volume, red blood cells, hemoglobin, mean corpuscular hemoglobin concentration, mean corpuscular hemoglobin, and mean corpuscular volume) of the formulated diets were higher than those of ogi, but lower than those of Cerelac. In conclusion, we established that the FPAB food sample was rated best in terms of protein quality over the other formulated diets. Therefore, a FPAB blend may be used as a substitute for ogi.

Efecto adverso en la calidad proteica de los alimentos de dietas con alto contenido de fibra dietaria / Adverse effect on the food protein quality of diets high in dietary fiber

Modern diet tends to change eating habits and there is a tendency to consume more processed foods. These changes in eating habits towards more consumption of processed food, and the recognized benefic effects of dietary fiber by consumers, tend to increase the number of "high fiber" foods in the market. Although the beneficial effects of dietary fiber on human health is widely recognized, this increased consumption of dietary fiber may also have adverse effects on digestion, absorption and utilization offood proteins. Research in the past has shown that the consumption of high dietary fiber diets have an adverse effect on certain indicators of protein quality. Therefore it becomes very important to study the physicochemical properties of the various sources of dietary fiber, as well as the presence of other factors, associated to the fibrous fraction, in their possible negative influence on the protein quality of rich dietary fiber diets.

La dieta moderna cambia los hábitos alimenticios y existe una tendencia al consumo de alimentos más procesados. El cambio de hábito alimentario hacia alimentos más procesados tiende a incrementar, algunas veces por propósitos publicitarios, aquellos alimentos procesados "altos en fibra". Si bien los efectos benéficos de la fibra dietética a la salud humana son ampliamente reconocidos, este aumento en el consumo de fibra dietética puede también tener efectos adversos en la digestión, absorción y utilización de la proteína de los alimentos. En las investigaciones revisadas se obtuvo que el consumo de dietas altas en fibra dietética tiene efecto adverso en ciertos indicadores de calidad proteica, por lo que la inclusión de fuentes proteicas con altos contenidos de fibra impone la necesidad de estudiar las características físico-químicas de la fibra dietética, así como la presencia de factores que pudieran unirse a la fracción fibrosa e influir negativamente en la calidad proteica.

Influência do processamento na qualidade proteica de novos cultivares de soja destinados à alimentação humana / Influence of processing on the protein quality of new soybean cultivars intended for human food

OBJETIVO: Avaliar o efeito do processamento na qualidade proteica de cultivares de soja destinados à alimentação humana. MÉTODOS: As dietas foram preparadas a partir dos grãos dos cultivares Embrapa 48, BRS 213, BRS 155 e UFVTN 105, que receberam tratamento térmico em estufa a 130 e 150°C, com posterior retirada ou não da casca para a produção das farinhas. Realizou-se ensaio biológico para avaliação de quociente de eficiência proteica, quociente de eficiência proteica líquida e digestibilidade verdadeira. RESULTADOS: Os valores de razão proteica líquida e digestibilidade das farinhas foram inferiores aos da caseína. As farinhas de soja com casca tratadas a 150ºC apresentaram melhores índices de qualidade proteica que as farinhas sem casca tratadas a 130ºC. O quociente de eficiência proteica e o quociente de eficiência proteica líquida dos cultivares Embrapa 48 e BRS 155 foram maiores (p<0,05) que os demais. O cultivar UFVTN 105 apresentou maior (p<0,05) digestibilidade quando processado a 130ºC. No tratamento a 150ºC, a digestibilidade foi inferior (p<0,05) para os cultivares BRS 213 e BRS 155. Não foi observada melhoria na digestibilidade da proteína de soja quando utilizado o cultivar com baixo teor de inibidor de tripsina (BRS 155) em comparação com o cultivar convencional (Embrapa-48). CONCLUSÃO: O tratamento térmico e a retirada ou não da casca interferiram na qualidade proteica de novos cultivares de soja destinados à alimentação humana, com melhores resultados para as farinhas com casca produzidas a partir de grãos tratados a 150ºC por 30 minutos. O tratamento térmico favoreceu a qualidade proteica das farinhas de soja convencionais, que obtiveram valores semelhantes aos dos cultivares sem inibidor de tripsina e superiores aos dos cultivares sem lipoxigenase.

OBJECTIVE: The aim of this study was to evaluate the effect of processing on the protein quality of new soybean cultivars intended for human food. METHODS: The diets were prepared from the cultivars Embrapa 48, BRS 213, BRS 155 and UFVTN 105. They were heat-treated in a vacuum oven at 130ºC and 150°C, with subsequent removal or not of the hull for the production of soybean meals. A biological assay was done to determine the protein efficiency ratio, net protein ratio and true protein digestibility. RESULTS: Soybean meals had lower protein efficiency ratio, net protein ratio and digestibility than casein. Whole soybean meals treated at 150ºC had a better protein quality index than refined soybean meals heat-treated at 130ºC. The protein efficiency ratio and net protein ratio of Embrapa 48 and BRS 155 cultivars were higher (p<0.05) than the other ones. The UFVTN 105 cultivar had the highest digestibility (p<0.05) when treated at 130ºC. Among the cultivars heat-treated at 150ºC, the BRS 213 and BRS 155 cultivars had the lowest digestibility (p<0.05). Protein digestibility of the cultivar with low trypsin inhibitor content (BRS 155) was not better than that of the conventional Embrapa-48 cultivar. CONCLUSION: Heating and removal or not of the hull affected the protein quality of the new soybean cultivars intended for human food. Whole soybean meals heat-treated at 150ºC for 30 minutes presented the best results. Heating improved the protein quality of the conventional soybean meals. Their protein quality was similar to that of the cultivars without trypsin inhibitor and better than that of the cultivars without lipoxygenases.

Efecto de la variedad y la fertilización en indicadores de calidad proteica in-vitro de dos variedades y una línea de garbanzo (cicer arietinum) / Variety and fertilization effect on indicators of protein quality in-vitro of two varieties and one line of chickpea (cicer arietinum)

Protein quality in relation to the degree of fertilization of two varieties (Costa and Blanco Sinaloa) and an advanced line (Hoga L10) of chickpeas obtained from the Campo Experimental Costa de Hermosillo, Sonora, Mexico from INFAP was evaluated. They were grown in similar conditions with 3 levels of nitrogen fertilization (60,120 and 200K/Ha.). Protein and non-protein nitrogen, digestibility and available lysine were analyzed. Significant differences between the varieties and the advanced line in protein and non-protein nitrogen and available lysine were found. The effect of the degree of fertilization on protein quality was significant, showing that a level ofl20KI Ha an increase is observed in protein and non-protein nitrogen and in the percent of digestibility. No significant differences were observed between 60 and 200KIHa. Available lysine was higher at the 200KIHa level. These indicators of protein quality can be used to complement commercial and agricultural aspects that are evaluated for improvement and selection of new varieties of chickpeas.

En este trabajo se evaluó la calidad proteica in-vitro en dos variedades y una línea avanzada de garbanzo, así como su relación con el grado de fertilización aplicado durante su cultivo. Se utilizaron dos variedades comerciales de garbanzo (Costa y Blanco Sinaloa) y una línea avanzada Hoga L10, sembradas en condiciones ambientales similares, con tres niveles de fertilización de nitrógeno (60, 120 y 200K/Ha.), las cuales fueron obtenidas del Campo Experimental Costa de Hermosillo, Sonora, México del INIFAP. Se llevó a cabo un análisis químico proximal, determinaciones de calidad proteica como: nitrógeno proteico y no proteico utilizando extracciones con ácido tricloroacético, digestibilidad in-vitro por el método multienzimático y lisina disponible. A excepción de digestibilidad in-vitro se observaron diferencias significativas entre las variedades y línea avanzada en: nitrógeno proteico, no proteico y lisina disponible. El efecto de la fertilización fue observado en todos las determinaciones de calidad proteica, los resultados indicaron que al aumentar el nivel de fertilización a 120K/Ha se obtiene un incremento significativo en el porcentaje de nitrógeno proteico y no proteico, así como el porcentaje de digestibilidad. Entre los niveles de 60 y 200K/Ha no se observaron diferencias significativas. La lisina disponible fue mayor en las variedades y líneas con nivel de fertilización de 200K/Ha. Estos indicadores de calidad proteica pueden complementar a los aspectos agronómicos y comerciales que son evaluados en los programas de mejoramiento, en la selección de nuevas variedades de garbanzo para su explotación comercial.

Evaluation of protein quality from genetically modified and organic soybean in two consecutives generations of wistar rats

The aim of this study was to evaluate the cumulative effects of using genetically modified and organic soybean in two generations of rats. Two consecutive generations of 64 Wistar rats denominated F0 and F1 were used. The animals from each generation were divided into three groups (n=8) and fed chow made of organic soybean, genetically modified soybean and casein. The PER, NPR and CAE were determined. ANOVA was applied to the results. In both the generations, a statistically significant (p<0.05) difference was found between the experimental groups and the control group. The organic soybean supplement with L-cystine provided a better use of this protein in comparison to the genetically modified soybean protein, which demonstrated that the soybean maintained its protein use, although always inferior to casein. Thus, soybean should be used with caution during the growth stages because even with supplements, it remained inferior in relation to the casein group.

Este estudo objetivou avaliar os efeitos cumulativos da utilização das sojas geneticamente modificada e orgânica em duas gerações de ratos. Utilizaram-se 64 ratos Wistar, de duas gerações consecutivas denominadas F0 e F1. Os animais de cada geração foram divididos em três grupos (n=8) alimentados com ração à base de soja orgânica, soja geneticamente modificada e caseína. Determinou-se o Quociente de Eficácia Protéica, Razão Protéica Líquida e Quociente de Eficácia Alimentar. Aos resultados aplicou-se ANOVA. Foi encontrada, em ambas as gerações uma diferença significativa (p<0,05) entre os grupos experimentais e o grupo controle. A suplementação dos grupos GOF0 e GOF1 com Lcistina proporcionou um melhor aproveitamento protéico em relação ao GGF0 e GGF1. Mostrando que a soja manteve seu aproveitamento, no entanto sempre inferior à caseína. Deve-se utilizar as sojas geneticamente modificada e orgânica com cautela na fase de crescimento, pois mesmo suplementada com L-cistina estas se mantiveram inferior ao grupo à base de caseína.

Composição de aminoácidos em gerações precoces de feijão obtidas a partir de cruzamentos controlados com parental de alto teor de cisteína / Amino acid composition in common bean early generations developed from cross with high cysteine content parental

Os objetivos deste trabalho foram avaliar a composição de aminoácidos em gerações precoces de feijão, obtidas a partir de cruzamentos controlados com genitor de alto teor de cisteína, e identificar plantas com alto teor de cisteína nos grãos. A partir do cruzamento entre 'TPS Nobre' x 'Minuano', foram obtidas as gerações F1, F1 recíproco, F2, F2 recíproco, retrocruzamento 1 e retrocruzamento 2. Os aminoácidos foram determinados por cromatografia líquida de alta performance (HPLC) e os dados obtidos foram submetidos à análise de variância e de variáveis canônicas. Os aminoácidos - cisteína, prolina, tirosina, arginina, isoleucina e histidina - apresentaram variabilidade genética entre os genitores e as gerações obtidas. Os teores de aminoácidos essenciais e não-essenciais observados nos genitores e nas gerações F1 e F1 recíproco foram adequados para uso na alimentação. As demais gerações apresentaram deficiência em aminoácidos sulfurados. As duas primeiras variáveis canônicas explicaram 96,43 por cento da variação total dos genótipos e dois grupos foram formados. Nenhuma planta da geração F2 é passível de seleção pelo programa de melhoramento para o desenvolvimento de populações segregantes de feijão com alto teor de cisteína nos grãos.

The objective of this research was to determine the amino acid composition of early generations in common bean developed from controlled crossings with high cysteine content parental and to identify plants with high cysteine content. 'TPS Nobre' x 'Minuano' were crossed and the F1, F1 reciprocal, F2, F2 reciprocal, backcross 1 e backcross 2 generations were obtained. The amino acid contents were determinated by liquid chromatography of high performance (HPLC) and the data were submitted to analysis of variance and cannonical variables. The cysteine, proline, tyrosine, arginine, isoleucine and histidine contents showed genetic variability between the parents and the generations. The essential and nonessential amino acids contents obtained from the parents, F1 and F1 reciprocal generations were appropriate to be consumed. Other generations showed deficiency of the sulfur amino acids. The two first cannonical variables explained 96.43 percent of the total variation of the genotypes and two groups were formed. None of the plants of the F2 generation is able to be selected by program of improvement to the development of segregating populations of common bean with high cysteine content.

Relationship between relative protein value and some in vitro indices of protein quality.

Besides amino acid composition of a protein, their bioavailability is an important determinant of the protein quality. In view of the observations over the last decade or two, implicating the small peptide uptake by the mammalian intestine as a major route of protein absorption, a few animal and plant proteins were subjected to sequential enzymatic digestion in vitro with pepsin, pancreatin + trypsin and erepsin and the release of amino acids as small (including dipeptides) and large peptides and free amino acids, was determined. The relative protein values of α-lactalbumin, egg whites, casein, gluten, zein and protein isolates of soyabeans and groundnuts was determined using rat growth method. It was observed that relative protein value were positively correlated with the essential amino acid index of protein, quantity of essential amino acids released as small peptides and the dipeptide content of enzymatic digests, while there was a negative correlation between relative protein value and essential amino acid content of large peptide fraction.

EVALUATION OF PROTEIN QUALITY FOR PIG BLOOD FIBRIN AND LIVER RESIDUE / 营养学报

Sixty Wistar rats were divided into 5 groups, 12 in each:1)Casein; 2) Fish powder (FP) ; 3) Fibrin; 4)Liver residue(LR) , 5)Nitrogen free(NF). The feeds for all groups of rats were at the level of 10% protein and at the same calories except NF. Growth test, nitrogen balance and recovery test were used and the levels of serum proteins and Hb were determined.The protein efficiency ratio (PER) of casein, FP, fibrin and LR were 1.90, 3.07, 2.61 and 1.28 respectively. Net protein ratio (NPR), apparent digestibility, true digestibility and net nitrogen ratio (NNR) were same as PER suggesting the protein quality of LR was low, FP was high and fibrin in the medium. The values of serum proteins also showed that 10% protein of LR could not maintain rats in health, but compared with casein and FP the nutritional quality of fibrin was high and could be used in feed industry or other products.The effects of proteins on hepatic microsomal enzyme were observed. The influence factors were discussed.

NUTRITIONAL EVALUATION OF PROTEIN——Ratio Coefficient of Amino Acid / 营养学报

The method of ratio coefficient of amino acid, based on the theory of amino acid balance, is a new one designed to evaluate nutritional value of food protein. The calculation and the meaning of Ratio Coefficient (RC) and Score of RC (SRC) are described. RC can be used to judge limit amino acid and to calculate the amount that shall be added to a fortified food. SRC can be used to evaluate nutritional quality of protein. A high correlation was obtained between SRC and Biological Value (BV), P