scholarly journals Isolation of enzymes involved in threonine biosynthesis from sorghum seeds

2004 ◽  
Vol 16 (2) ◽  
pp. 95-104 ◽  
Author(s):  
Renato Rodrigues Ferreira ◽  
Ariane Vendemiatti ◽  
Lyndel Wayne Meinhardt ◽  
Peter John Lea ◽  
Ricardo Antunes Azevedo
Keyword(s):  
Amino Acids ◽  
Essential Amino Acids ◽  
Aspartate Kinase ◽  
Homoserine Dehydrogenase ◽  
Higher Plant ◽  
Level Of Activity ◽  
Immature Seeds ◽  
Aspartate Pathway ◽  
Threonine Biosynthesis

Cereal seeds are poor in essential amino acids, particularly lysine, tryptophan and threonine. The amino acids lysine and threonine are synthesized in the aspartate pathway. Although most of the enzymes of the aspartate pathway have been isolated and characterized in higher plant species, the metabolism of lysine and threonine is totally unknown in sorghum. We have isolated two enzymes, aspartate kinase (AK) and homoserine dehydrogenase (HSDH) from sorghum. Optimum assay conditions were established for the determination of AK and HSDH activities. The highest level of activity was observed in immature seeds. AK was shown to be inhibited by threonine and lysine indicating the existence of at least two isoenzymes, one sensitive to threonine inhibition and the other sensitive to lysine inhibition with the latter being predominant in sorghum seeds. HSDH was shown to be inhibited by threonine indicating the existence of a threonine-sensitive HSDH, however, most of the activity was not inhibited by threonine, suggesting the existence of a second predominant isoenzyme of HSDH resistant to threonine inhibition.

Genetic control of lysine metabolism in maize endosperm mutants

2004 ◽  
Vol 31 (4) ◽  
pp. 339 ◽  
Author(s):  
Ricardo A. Azevedo ◽  
Catherine Damerval ◽  
Peter J. Lea ◽  
Jacques Landry ◽  
Cláudia M. Bellato ◽  
...  
Keyword(s):  
Amino Acids ◽  
Qualitative Study ◽  
Aspartate Kinase ◽  
Maize Endosperm ◽  
Homoserine Dehydrogenase ◽  
Saccharopine Dehydrogenase ◽  
Endosperm Mutants ◽  
Mutant Lines ◽  
Mutant Genes ◽  
Lysine Metabolism

The capacity of three maize endosperm opaque mutants (o10, o11 and o13) to accumulate soluble lysine in the seed in relation to their wildtype counterpart, W22+, was investigated. The W22o13 and W22o11 mutants exhibited 278% and 186% increases in soluble lysine, respectively, while for W22o10, a 36% decrease was observed, compared with the wildtype. A quantitative and qualitative study of the N constituents of the endosperm has been conducted and data obtained for the total protein, non-protein N, soluble amino acids, albumins / globulins, zeins and glutelins present in the seed of the mutants. Following 2D–PAGE, a total of 38 different forms of zein polypeptides were detected and considerable differences were noted between the three mutant lines. The metabolism of lysine was also studied by analysis of the enzymes aspartate kinase, homoserine dehydrogenase, lysine 2-oxoglutarate reductase and saccharopine dehydrogenase, which exhibited major changes in activity, depending on the genotype, suggesting that the mutant genes may have distinct regulatory activities.

Effect of heat processing on ruminal and post-ruminal disappearance of essential and non-essential amino acids of Iranian whole soybeans

2007 ◽  
Vol 2007 ◽  
pp. 165-165
Author(s):  
M. Hassan Fathi Nasri ◽  
Mohsen Danesh Mesgaran ◽  
Reza Valizadeh ◽  
Ali Nikkhah
Keyword(s):  
Amino Acids ◽  
Physical Method ◽  
Essential Amino Acids ◽  
High Energy ◽  
Heat Processing ◽  
Special Importance ◽  
Rumen Microbes ◽  
Heat Treated ◽  
Physical Processing

Whole soybean (SB) is used as a high energy-protein supplement for dairy cows, but the protein is highly degradable by rumen microbes. Various chemical and physical processing has been suggested to decrease ruminal protein degradability, that heat processing is the most commonly used physical method. Modern systems for protein evaluations in ruminants are moving in the direction of predicting absorption of amino acids from the small intestine, so the determination of intestinal digestibility of amino acids is of special importance particularly in heat-treated feedstuffs. The objective of this research was to elucidate the effects of roasting and steep-roasting on ruminal and post-ruminal disappearance of essential and non-essential amino acids (EAA and NEAA) of Iranian SB.

Evaluation of the Role of Nutrition in Lobster Recruitment

1986 ◽  
Vol 43 (11) ◽  
pp. 2320-2327 ◽  
Author(s):  
J. D. Castell ◽  
J. C. Kean
Keyword(s):  
Amino Acids ◽  
Essential Amino Acids ◽  
Field Application ◽  
Nutritional Requirements ◽  
Egg Viability ◽  
Good Opportunity ◽  
Broodstock Nutrition

Many of the hypotheses and proposals presented here on the role of nutrition in lobster recruitment have been derived from research on other aquatic animals. Little research has focused on the determination of nutritional requirements of lobsters and even that has been primarily with small juveniles (36–1000 mg). Despite the tacit acknowledgement that maternal fecundity and egg viability are a function of quantity and quality of available food, little is known about the nutrition of reproductively mature lobsters. The importance of broodstock nutrition and possible methods for evaluating nutritional status are discussed. Information on protein, essential amino acids, vitamins, minerals, carbohydrates, and lipids is summarized. Additionally, some proposals for field application of nutritional response criteria used in the laboratory are discussed. Though research on larvae adult broodstock nutrition, effects of environmental factors (e.g. temperature, salinity, photoperiod, etc.), as well as many other aspects of nutrition is yet to be done, there is "good opportunity" for nutrition to be a significant part of the current lobster recruitment research program.

scholarly journals Determination of Essential Amino Acids Involved in the CD4-Independent Tropism of the X4 Human Immunodeficiency Virus Type 1 m7NDK Isolate: Role of Potential N Glycosylations in the C2 and V3 Regions of gp120

2001 ◽  
Vol 75 (11) ◽  
pp. 5425-5428 ◽  
Author(s):  
Julie Dumonceaux ◽  
Caroline Goujon ◽  
Veronique Joliot ◽  
Pascale Briand ◽  
Uriel Hazan
Keyword(s):  
Amino Acids ◽  
Human Immunodeficiency Virus ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Essential Amino Acids ◽  
Site Directed Mutagenesis ◽  
Immunodeficiency Virus

ABSTRACT Seven mutations in the C2, V3, and C3 regions of gp120 are implicated in the tropism of the first CD4-independent human immunodeficiency virus type 1 isolate, m7NDK. Site-directed mutagenesis revealed that three amino acids are essential to maintain this tropism, one in the C2 region and two in the V3 loop. Two mutations implied N glycosylation modifications.

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