The Uptake of Methionine-S35 by the Chick Embryo and its Inhibition by Ethiònine

Development ◽  
1955 ◽  
Vol 3 (1) ◽  
pp. 44-58
Author(s):  
M. Feldman ◽  
C. H. Waddington
Keyword(s):  
Amino Acids ◽  
Chick Embryo ◽  
Protein Metabolism ◽  
Culture Medium ◽  
Molecular Size ◽  
Radioactive Isotopes ◽  
Surface Coat ◽  
Amphibian Embryo ◽  
Structural Analogues ◽  
External Sources

It seems probable that the synthesis of new proteins must play one of the most fundamental roles in embryonic development. As part of a programme of investigating protein metabolism in morphogenesis (see Waddington & Sirlin, 1954), a study has begun on the incorporation into the early chick embryo of amino-acids labelled with radioactive isotopes and the effect of some of their structural analogues on their metabolism. It seems that for this particular aspect of study the chick embryo has two main advantages over the amphibian: (1) Since it depends for metabolites on external sources (yolk, albumen, culture medium), it is much easier to interfere with the normal pathway of protein synthesis by means of specific antimetabolites. (2) Unlike the amphibian embryo, it does not possess a surface coat, which greatly inhibits the absorption of substances of even small molecular size in amphibian embryos (Friedberg & Eakin, 1949).

Protein metabolism of amphibian embryo. IV. Quantitative changes in free and non-protein amino acids

1953 ◽  
Vol 124 (2) ◽  
pp. 263-277 ◽  
Author(s):  
Phyllis B. Kutsky ◽  
Richard M. Eakin ◽  
William E. Berg ◽  
J. Lee Kavanau
Keyword(s):  
Amino Acids ◽  
Protein Metabolism ◽  
Amphibian Embryo ◽  
Protein Amino Acids ◽  
Quantitative Changes

scholarly journals Effect of long-term refeeding on protein metabolism in patients with cirrhosis of the liver

1997 ◽  
Vol 77 (2) ◽  
pp. 197-212 ◽  
Author(s):  
Jens Kondrup ◽  
Klaus Nielsen ◽  
Anders Juul
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Protein Degradation ◽  
Protein Metabolism ◽  
Cirrhosis Of The Liver ◽  
N Balance ◽  
Whole Body ◽  
Protein Requirement ◽  
Protein Utilization ◽  
Igf I

Patients with cirrhosis of the liver require an increased amount of protein to achieve N balance. However, the utilization of protein with increased protein intake, i.e. the slope from regression analysis of N balance v. intake, is highly efficient (Nielsen et al. 1995). In the present study, protein requirement and protein utilization were investigated further by measuring protein synthesis and degradation. In two separate studies, five or six patients with cirrhosis of the liver were refed on a balanced diet for an average of 2 or 4 weeks. Protein and energy intakes were doubled in both studies. Initial and final whole-body protein metabolism was measured in the fed state by primed continous [15N]glycine infusion. Refeeding caused a statistically significant increase of about 30% in protein synthesis in both studies while protein degradation was only slightly affected. The increase in protein synthesis was associated with significant increases in plasma concentrations of total amino acids (25%), leucine (58%), isoleucine (82%), valine (72%), proline (48%) and triiodothyronine (27%) while insulin, growth hormone, insulin-like growth factor (IGF)-I and IGF-binding protein-3 were not changed significantly. The results indicate that the efficient protein utilization is due to increased protein synthesis, rather than decreased protein degradation, and suggest that increases in plasma amino acids may be responsible for the increased protein synthesis. A comparison of the patients who had a normal protein requirement with the patients who had an increased protein requirement suggests that the increased protein requirement is due to a primary increase in protein degradation. It is speculated that this is due to low levels of IGF-I secondary to impaired liver function, since initial plasma concentration of IGF-I was about 25% of control values and remained low during refeeding.

Role of insulin and branched-chain amino acids in regulating protein metabolism during fasting

1990 ◽  
Vol 258 (6) ◽  
pp. E907-E917 ◽  
Author(s):  
M. Frexes-Steed ◽  
M. L. Warner ◽  
N. Bulus ◽  
P. Flakoll ◽  
N. N. Abumrad
Keyword(s):  
Amino Acids ◽  
Protein Metabolism ◽  
Insulin Dose ◽  
Group Iii ◽  
Group I ◽  
Tissue Sensitivity ◽  
Branched Chain ◽  
Independent Effects ◽  
Dose Dependent

This study examines the independent effects of insulin and amino acids on protein metabolism after a 12-h and 4-day fast in healthy volunteers. Leucine (Leu) kinetics were examined during sequential insulin infusions of 0 (group I) or 0.0125 (groups II and III), 1.2, and 10 mU.kg-1.min-1. Plasma Leu was maintained at 12-h fasted levels in groups I and II and at 84-h fasted levels in group III. Four-day fast (vs. 1 day, P less than 0.01) was associated with a 79% drop in plasma insulin and elevations in plasma Leu (122%), Leu rates of appearance (Ra) (21%), and Leu oxidation (56%), and no change in nonoxidative rates of disappearance (Rd). Insulin resulted in a dose-dependent suppression of endogenous Leu Ra with group III = I greater than II. Leu oxidation rose 1.7-fold in group III at the highest insulin dose but remained stable in the two other groups. In conclusion, 4-day fasting is associated with enhanced proteolysis and Leu oxidation with no change in nonoxidative Rd (protein synthesis). Elevated branched-chain (and other) amino acids were required to restore tissue sensitivity and specificity to the effects of insulin on protein metabolism after 4 days of fasting.

FURTHER STUDIES ON THE DUAL REQUIREMENT FOR PHENYLALANINE AND TYROSINE IN TISSUE CULTURE

1961 ◽  
Vol 39 (5) ◽  
pp. 925-932 ◽  
Author(s):  
Helen J. Morton ◽  
Joseph F. Morgan
Keyword(s):  
Amino Acids ◽  
Tissue Culture ◽  
Chick Embryo ◽  
Heart Cells ◽  
Present System ◽  
Chick Heart ◽  
High Concentrations ◽  
Chick Embryo Heart ◽  
Embryo Heart ◽  
Related Compounds

Seventeen structurally related compounds were tested for their ability to substitute for phenylalanine or tyrosine in the nutrition of chick embryo heart fragments. DL-Alanyl-DL-phenylalanine replaced phenylalanine. All other compounds had negligible effects, and most were toxic at high concentrations. β-Phenylserine, a phenylalanine antagonist, actually prolonged the survival of chick heart cells but only if both phenylalanine and tyrosine were present. Similarly, optimal reversal of β-phenylserine toxicity was dependent on the presence of both amino acids. Although phenylalanine and tyrosine are not interconvertible in the present system, it has been shown that three phenylalanine antagonists, p-fluorophenylalanine, β-2-thienylalanine, and β-phenylserine, can be identified by their relationship to tyrosine, rather than to phenylalanine.

scholarly journals The Capsid (ORF2) Protein of Hepatitis E Virus in Feces Is C-Terminally Truncated

Pathogens ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 24
Author(s):  
Takashi Nishiyama ◽  
Koji Umezawa ◽  
Kentaro Yamada ◽  
Masaharu Takahashi ◽  
Satoshi Kunita ◽  
...  
Keyword(s):  
Amino Acids ◽  
Cell Culture ◽  
Structure Prediction ◽  
Hepatitis E Virus ◽  
Culture Media ◽  
Molecular Size ◽  
Hepatitis E ◽  
Terminal Region ◽  
Translation Product ◽  
Orf2 Protein

The hepatitis E virus (HEV) is a causative agent of hepatitis E. HEV virions in circulating blood and culture media are quasi-enveloped, while those in feces are nonenveloped. The capsid (ORF2) protein associated with an enveloped HEV virion is reported to comprise the translation product of leucine 14/methionine 16 to 660 (C-terminal end). However, the nature of the ORF2 protein associated with fecal HEV remains unclear. In the present study, we compared the molecular size of the ORF2 protein among fecal HEV, cell-culture-generated HEV (HEVcc), and detergent-treated protease-digested HEVcc. The ORF2 proteins associated with fecal HEV were C-terminally truncated and showed the same size as those of the detergent-treated protease-digested HEVcc virions (60 kDa), in contrast to those of the HEVcc (68 kDa). The structure prediction of the ORF2 protein (in line with previous studies) demonstrated that the C-terminal region (54 amino acids) of an ORF2 protein is in flux, suggesting that proteases target this region. The nonenveloped nondigested HEV structure prediction indicates that the C-terminal region of the ORF2 protein moves to the surface of the virion and is unnecessary for HEV infection. Our findings clarify the maturation of nonenveloped HEV and will be useful for studies on the HEV lifecycle.

scholarly journals Emilin, a component of elastic fibers preferentially located at the elastin-microfibrils interface.

1993 ◽  
Vol 121 (1) ◽  
pp. 201-212 ◽  
Author(s):  
G M Bressan ◽  
D Daga-Gordini ◽  
A Colombatti ◽  
I Castellani ◽  
V Marigo ◽  
...  
Keyword(s):  
Extracellular Matrix ◽  
Chick Embryo ◽  
Culture Medium ◽  
Close Contact ◽  
Corneal Stroma ◽  
Ultrastructural Level ◽  
Elastic Fibers ◽  
Specific Antibodies ◽  
Gold Particles ◽  
Immunofluorescence Studies

The fine distribution of the extracellular matrix glycoprotein emilin (previously known as glycoprotein gp115) (Bressan, G. M., I. Castellani, A. Colombatti, and D. Volpin. 1983. J. Biol. Chem. 258: 13262-13267) has been studied at the ultrastructural level with specific antibodies. In newborn chick aorta the protein was exclusively found within elastic fibers. In both post- and pre-embedding immunolabeling emilin was mainly associated with regions where elastin and microfibrils are in close contact, such as the periphery of the fibers. This localization of emilin in aorta has been confirmed by quantitative evaluation of the distribution of gold particles within elastic fibers. In other tissues, besides being associated with typical elastic fibers, staining for emilin was found in structures lacking amorphous elastin, but where the presence of tropoelastin has been demonstrated by immunoelectron microscopy. This was particularly evident in the oxitalan fibers of the corneal stroma, in the Descemet's membrane, and in the ciliary zonule. Analysis of embryonic aorta revealed the presence of emilin at early stages of elastogenesis, before the appearance of amorphous elastin. Immunofluorescence studies have shown that emilin produced by chick embryo aorta cells in culture is strictly associated with elastin and that the process of elastin deposition is severely altered by the presence of antiemilin antibodies in the culture medium. The name of the protein was derived from its localization at sites where elastin and microfibrils are in proximity (emilin, elastin microfibril interface located protein).

Mise en évidence d'une activité uréasique chez Streptococcus thermophilus

1988 ◽  
Vol 34 (6) ◽  
pp. 818-822 ◽  
Author(s):  
V. Juillard ◽  
M. J. Desmazeaud ◽  
H. E. Spinnler
Keyword(s):  
Amino Acids ◽  
Urease Activity ◽  
Culture Medium ◽  
Colorimetric Method ◽  
Streptococcus Thermophilus ◽  
Stationary Growth Phase ◽  
Optimal Temperature ◽  
Ammonium Ions ◽  
Stationary Growth ◽  
Optimal Ph

In Streptococcus thermophilus CNRZ 404, the presence of urease activity was demonstrated by means of a specific colorimetric method for ammonium ions. The main physicochemical properties of the enzyme were determined. The Km with urea as substrate was 1.19 mM and the optimal pH was approximately 7.5. Because both thermolability and enzyme activity increased as the temperature was increased to 70 °C, the optimal temperature could not be determined with precision. Urease activity was maximal at the beginning of the stationary growth phase; it was stimulated by the presence of urea and of certain amino acids such as arginine and glutamic acid in the culture medium. This activity has been detected in several other strains of Streptococcus thermophilus. [Translated by the journal]

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