吉林产哈士蟆中氨基酸含量的研究

应用日立835—50型氨基酸自动分析仪,对哈士蟆十种干样品进行了氨基酸成分的比较分析,结果表明:①必需氨基酸含量由高至低依次为雄蛙腿肉,雌蛙腿肉、卵、整只雄蛙、整只雌蛙、雄蛙皮、哈士蟆油、雌蛙皮、雌蛙腿骨、雄蛙腿骨。②氨基酸总量由高至低依次为雄蛙腿肉、雌蛙腿肉、雄蛙皮、雌蛙皮、卵、整只雄蛙、整只雌蛙、哈士蟆油、雌蛙腿骨、雄蛙腿骨。③雄蛙腿肉和雌蛙腿肉中各种氨基酸含量由大到小的排列顺序基本一致。     

赤眼鳟肉质氨基酸成分研究初报

测定了赤眼鳟肉氨基酸组成。结果表明 ,赤眼鳟肉含有 17种氨基酸 ,其中赖氨酸含量最高 ,总氨基酸中的必须氨基酸的质量分数为 5 7.8%。     

白斑狗鱼含肉率及其营养价值的分析

测定了6尾白斑狗鱼(Esox lucius)的含肉率和营养成分,并与部分淡水优质经济鱼类进行了比较.结果表明:白斑狗鱼含肉率为64.8%,粗蛋白含量和脂肪含量分别为19.1%和1.4%,17种氨基酸总量为17.38%,其中7种必需氨基酸总量为8.14%,鲜味氨基酸总量为6.36%.必需氨基酸总量占氨基酸总量的45.73%,低于鸡蛋蛋白模式,但明显高于WHO/FAO模式.必需氨基酸指数为76.35,根据化学评分计算结果,得出第一限制性氨基酸为缬氨酸,第二限制性氨基酸为蛋氨酸,第三限制性氨基酸为异亮氨酸.结果提示,白斑狗鱼是一种营养价值较高的鱼类.     

黄鳝含肉率及氨基酸成分分析

测定了黄鳝的含肉率及其氨基酸含量 ,对其营养价值进行了评定。该鱼 (鲜样 )含肉率 75 .12 % ;水分 6 2 .9% ;肌肉粗蛋白 (g/10 0g干样 ) 74.5 6 % ;水解氨基酸总量 5 6 .11% ;其中必需氨基酸 2 0 .83% ;占氨基酸总量的 37.12 %。认为黄鳝是一种营养价值和养殖价值都比较高的淡水养殖鱼类 ,具有良好的开发利用前景。     

不同年龄的黄芪氨基酸成份

应用日立835—50型氨基酸自动分析仪,对黄芪3种干样品进行了氨基酸成分的分析,结果表明:①必须氨基酸含量由高至低依次为3年、1年、2年。②总氨基酸含量由高至低依次为3年1年、2年。     

五种野生食用菌干品营养及鲜味成分分析和评价

对野生松蘑、牛肝菌、白蘑、鸡爪蘑、肉蘑五种食用菌子实体中的蛋白质氨基酸、游离氨基酸和呈味核苷酸进行测定,采用氨基酸评分(AAS)、化学评分(CS)、必需氨基酸指数(EAAI)和等鲜浓度(EUC)评价方法,对五种野生食用菌的营养和鲜味进行评价。结果表明:野生食用菌的AAS、CS、EAAI、EUC存在明显差异。白蘑营养及鲜味最好,其余依次为松蘑、鸡爪蘑、牛肝菌,肉蘑最差。     

五种野生食用菌干品营养及鲜味成分分析和评价北大核心CSCD

对野生松蘑、牛肝菌、白蘑、鸡爪蘑、肉蘑五种食用菌子实体中的蛋白质氨基酸、游离氨基酸和呈味核苷酸进行测定,采用氨基酸评分(AAS)、化学评分(CS)、必需氨基酸指数(EAAI)和等鲜浓度(EUC)评价方法,对五种野生食用菌的营养和鲜味进行评价。结果表明:野生食用菌的AAS、CS、EAAI、EUC存在明显差异。白蘑营养及鲜味最好,其余依次为松蘑、鸡爪蘑、牛肝菌,肉蘑最差。     

黑龙江林蛙不同部位中氨基酸的含量分析

采用茚三酮柱后衍生-氨基酸分析法,对黑龙江林蛙油、卵、皮中17种氨基酸的组成和含量进行测定。结果显示黑龙江林蛙油、卵、皮均含有17种氨基酸,氨基酸总量分别为356.5 mg.g-1,525.1 mg.g-1,752.5 mg.g-1,其中必需氨基酸分别占氨基酸总量的46.06%,38.89%,33.33%。通过对黑龙江林蛙油、卵、皮中氨基酸含量的对比分析,表明林蛙油中氨基酸的营养价值最高。     

食源性蛋白质水解度常数htot值的测定

利用全自动氨基酸分析仪,对植物性蛋白质、动物性蛋白质和海洋蛋白质这三类蛋白质中的氨基酸含量进行测定,并对这三类蛋白质的htot值进行了计算、分析。结果显示,这三类蛋白质的htot值分别为:猪后肘肉7.62mmol.g-1、猪五花肉7.63mmol.g-1、鸡腿肉7.65mmol.g-1、大米7.44mmol.g-1、玉米7.57mmol.g-1、花生仁7.55mmol.g-1、鳗鱼肉7.64mmol.g-1、扇贝肉7.71mmol.g-1、牡蛎肉7.94mmol.g-1、章鱼肉7.79mmol.g-1。比较可知,这三类蛋白质中每克纯蛋白所含的肽键毫摩尔数为海洋蛋白质>动物性蛋白质>植物性蛋白质,为蛋白质水解度的测定提供了科学依据。     

山茱萸果皮及果核化学成分的研究

山茱萸(Cornus officinalis Sieb et Zucc.)的果皮—萸肉,是我国的传统中药材之一,经分析含有16种氨基酸和丰富的维生素B_2、维生素C,以及24种矿物质。存放三年后的萸肉,其氨基酸及维生素B_2的含量均有明显的下降,因此,萸肉作为一种中药材不宜存放太久,否则要影响药材的质量。在山茱萸果皮的加工过程中其果核弃之烧毁,但果核中含有丰富的营养物质,可以综合利用。     

Molecular evidence for species status of the endangered Hainan peacock pheasant

The Hainan peacock pheasant is an endangered taxon found only on Hainan Island of China. Due to lack of detailed taxonomic studies, whether it is a subspecies of the grey peacock pheasant (Polyplectron bicalcaratum katsumatae) or a full species (Polyplectron katsumatae) remained unclear. We used molecular markers, including the complete mitochondrial cytochrome b gene and intron G of the nuclear ovomucoid gene, to reevaluate the taxonomy of the Hainan peacock pheasant. The results showed phylogeographic monophyly and large genetic distance between the Hainan peacock pheasant and the grey peacock pheasant. Sequence differences corroborated the species-level distinction between these two peacock pheasants, which were inferred to have diverged about 1.4+/-0.3 million years ago, near the time Hainan Island became separated from mainland China. Because the population density of the Hainan peacock pheasant is very low in its tropical forest on the island and the wild population is declining, it is now becoming severely endangered and should be ranked as the rarest species in the Order Galliformes in China. Our results increase the urgency of getting more morphological data to support the classification of the Hainan peacock pheasant as a distinct species and taking more conservation action immediately to protect this endangered island species.     

黄伞菌丝蛋白质营养价值评价

本文测定了黄伞Pholiotaadiposa菌丝粗蛋白含量和氨基酸组成,采用国际上通用的营养价值评价方法,对其蛋白质的营养价值进行全面评价,并与营养价值较高的白灵侧耳Pleurotusnebrodensis、刺芹侧耳Pleurotuseryngii和金顶侧耳Pleurotrscitrinopileatus进行比较。分析结果表明,黄伞菌丝的必需氨基酸含量最高,占其氨基酸总量的43.9%,蛋白质的氨基酸评分(AAS)、化学评分(CS)、必需氨基酸指数(EAAI)、生物价(BV)、营养指数(NI)和氨基酸比值系数分(SRCAA)分别为92.0、71.3、88.5、84.8、40.4和78.8,六项指标均比参比食用菌高。结果说明黄伞菌丝具有很高的营养价值。     

Changes with aging in the levels of amino acids in rat CNS structural elements I. Glutamate and related amino acids

Glutamate and related amino acids were determined in 53 discrete brain areas of 3-and 29-month-old male Fischer 344 rats microdissected with the punch technique. The levels of amino acids showed high regional variation-the ratio of the highest to lowest level was 9 for aspartate, 5 for glutamate, 6 for glutamine, and 21 for GABA. Several areas were found to have all four amino acids at very high or at very low level, but also some areas had some amino acids at high, others at low level. With age, in more than half of the areas, significant changes could be observed, decrease occurred 5 times more frequently than increase. Changes occurred more often in levels of aspartate and GABA than in those of glutamate or glutamine. The regional levels of glutamate and its related amino acids show severalfold variations, with the levels tending to decrease in the aged brain.     

Direct and indirect effects of an introduced piscivore, <Emphasis Type="Italic">Cichla kelberi</Emphasis> and their modification by aquatic plants

The non-native peacock bass (Cichla kelberi) is causing freshwater fish extinctions in the tropical regions around the world, but there are very few studies on its interaction with native species. This study, based on a mesocosm experiment, examined direct and indirect effects of a non-native peacock bass on the native prey in Paraná River, Brazil, and tested whether these effects were mitigated by aquatic vegetation. Feeding activity of most prey was unaffected by the presence of peacock bass. All prey were consumed in the absence of vegetation; whereas a marginally significant decrease in mortality was observed in the vegetated habitats. Overall, peacock bass had minor indirect effects on prey foraging, but very significant direct effects on prey survival. As aquatic plants provide very limited protection to native prey, vegetated habitats are unlikely to slow down the decline in biodiversity resulting from this invasive species and conservation measures may need to consider other ways to ensure survival of the source populations.     

Cationic and anionic amino acid transport studies in rat red blood cells

The transport of L-proline, L-lysine and L-glutamate in rat red blood cells has been studied. L-proline and L-lysine uptake were Na⁺-independent. When the concentration dependence was studied both showed a non-saturable uptake assimilable to a difussion-like process, with high Kd values (0.718 and 0.191 min^–1 for L-proline and L-lysine respectively). Rat red blood cells showed high impermeability to L-glutamate. No sodium dependence was observed and the Kd value was low (0.067 min^–1). Our results show firstly, that rat red blood cells do not have amino acid transport systems for anionic and cationic amino acids and secondly that erythrocytes show no sodium-dependent L-proline transport, and that these cells are very permeable to this amino acid.Abbreviations MeAIB methyl aminoisobutyric acid     

Studies on the mechanism of induction of hypercholesterolemia in rabbits by high dietary levels of amino acids

Increasing the proportion of an amino acid mixture corresponding to casein in a low-fat, cholesterol-free, semipurified diet fed to rabbits causes a progressive increase in serum total and low density lipoprotein cholesterol, and the effect appears to be due primarily to the essential amino acids in the mixture. Our recent studies have also shown that the variations in serum cholesterol in response to different levels of the amino acid mixture are not associated with any changes in fecal excretion of cholesterol or bile acids. Further attempts to understand the mechanism of action of dietary amino acids on serum cholesterol levels have shown the following: (1) no correlation with levels of plasma amino acids, either in the fasting or postprandial state: (2) no correlation with serum levels of thyroid hormones: (3) no relationship to activity of hepatic or intestinal microsomal hydroxymethylglutaryl coenzyme A reductase: (4) no corresponding effects on the activities of cholesterol esterifying enzymes of intestinal mucosa: and (5) no correlation with the degree of esterification of cholesterol in very low or low density lipoproteins. Further studies are required to identify the specific amino acids responsible for the hypercholesterolemic effects and to determine the mechanisms involved.     

Purification and Characterization of a Cl−-Activated Aminopeptidase from Bovine Skeletal Muscle

To elucidate the mechanisms involved in the increase in free amino acids during postmortem storage of meat, a novel aminopeptidase was purified from bovine skeletal muscle by ammonium sulfate fractionation and successive chromatographies such as DEAE-cellulose, Sephacryl S-200, Hydroxyapatite, Phenyl-Sepharose, and Hi-Trap affinity column chromatography. The molecular mass of the enzyme was found to be 58 kDa on SDS–PAGE. This enzyme had optimum pH at around 7.5, and preferably hydrolyzed Ala-β-naphthylamide (-NA) in amino acid-NAs. The activity was strongly inhibited by phenylmethansulfonyl fluoride (PMSF) and bestatin, suggesting that it is to be classified as a serine protease. Moreover, the activity was enhanced by chloride and nitrate ions, which is the most remarkable property of this enzyme. The enzyme appeared to be involved in the increase in free amino acids during postmortem storage of meat.     

Genetic screening of Lactobacillus sakei and Lactobacillus curvatus strains for their peptidolytic system and amino acid metabolism, and comparison of their volatilomes in a model system

A total of 51 Lactobacillus sakei and 28 Lactobacillus curvatus strains from different origins were screened for their potential to produce biogenic amines (BAs), and for their diversity of peptidolytic systems and specific aminotransferases (AraT, BcaT) that initiate amino acid conversion to volatiles relevant for aroma formation in meat products. The profiles of volatiles formed (volatilomes) were analysed in the headspace of fermentations by solid phase microextraction followed by GC-MS analysis. Tyramine-forming potential was detected only within L. curvatus and was strain-dependent. Histamine decarboxylase (HDC) activity could only be detected in one L. sakei strain, previously described as histidine decarboxylase positive (HDC⁺). Peptide transporters and peptidases were nearly ubiquitous in L. sakei and only a few strains lacked single peptidases. In L. curvatus, differences were detected in the occurrence of peptidase genes detected with PCR primers derived from L. sakei. All strains lacked known aminotransferases specific for branched-chain amino acids (BCAAs) and aromatic amino acids (ACAAs). Although L. sakei is suggested as a genetically very heterogenous species, and relatedness between L. curvatus and L. sakei at the genomic level is rather low, they appeared to be nearly uniform in the genes forming the peptidolytic system. The volatilomes of L. sakei and L. curvatus strains were qualitatively nearly identical. However, slight differences in the formation of single volatile compounds and the interaction with staphylococci may impact upon sausage fermentation which occurs over a period of many weeks. Among the compounds expected to contribute to the aroma were dimethyldisulphide, 3-methyl-1-butanol, acetic acid, 1-butanol and butanoic acid.