Two Forms of Herbicide-Sensitive Acetolactate Synthase under Different Control by 2-Oxobutyrate in Rhodospivillum rubrum

1990 ◽  
Vol 45 (9-10) ◽  
pp. 999-1003
Author(s):  
Jobst-Heinrich Klemme ◽  
Irmgard Schneider
Keyword(s):  
Amino Acids ◽  
Enzyme Activity ◽  
Rhodospirillum Rubrum ◽  
Culture Media ◽  
Acetolactate Synthase ◽  
Branched Chain Amino Acids ◽  
Standard Test ◽  
Lag Phase ◽  
Test Mixture ◽  
Branched Chain

Regulation of acetolactate synthase (ALS, EC 4.1.3.18) in the phototrophic prokaryote Rhodospirillum rubrum was studied. In cell free extracts of 5 strains investigated, enzyme activity was very labile (about 80% loss of activity within 12h during storage at 4 °C) but was stabilized to some extent by 10 (μM FAD and 20 vol.% glycerol. By filtration of extracts through Superose 6 HR gels (FPLC technique), ALS activity of all strains was separated in two fractions of 200 and 600 kDa, respectively. The enzyme fractions had about the same affinity to pyruvate (ATm = 1.6 - 1.8 m M) , the same sensitivity to L-valine (50 and 65% inhibition by 0.1 m M valine in the standard test mixture) and the herbicide sulfometuron methyl (90 and 92% inhibition by 1 μM herbicide), but differed greatly in their sensitivity to inhibition by 0.4 m NaCl. In culture media with 2-oxobutyrate (2-OB), growth began only after a lag-phase of several days (5 days with 1 mM of the inhibitor). Cells grown in the presence of 2-OB had a reduced total ALS activity and did not contain the 200 kDa fraction. The inhibition of ALS by valine was noncompetitive in respect to pyruvate (K1= 0.l m M ) . From other branched-chain amino acids tested (L-leucine, L-isoleucine, norvaline, norleucine) only isoleucine was inhibitory (K1; = 3.1 m M )

Rapid Germination of Sulfonylurea-ResistantKochia scopariaL. Accessions is Associated with Elevated Seed Levels of Branched Chain Amino Acids

Weed Science ◽  
1993 ◽  
Vol 41 (1) ◽  
pp. 18-22 ◽  
Author(s):  
William E. Dyer ◽  
Peng W. Chee ◽  
Peter K. Fay
Keyword(s):  
Amino Acids ◽  
Thermal Gradient ◽  
Feedback Inhibition ◽  
Acetolactate Synthase ◽  
Branched Chain Amino Acids ◽  
Resistant Accession ◽  
Early Germination ◽  
Percent Germination ◽  
Soil Temperatures ◽  
Branched Chain

Field observations indicate that sulfonylurea-resistant kochia may germinate at lower soil temperatures and/or germinate more rapidly than susceptible kochia in the absence of herbicide. To investigate this possibility, seeds from three resistant and two susceptible kochia accessions were germinated at temperatures ranging from 4.6 to 13.2 C on thermal gradient plates. At 4.6 and 13.2 C, germination rates of all resistant accessions were higher than susceptible accessions, while germination rates of one resistant accession were higher than susceptible accessions at 7.2 and 10.5 C. Percent germination of all resistant accessions was significantly higher than susceptible accessions after 48 h at 4.6 C. At higher temperatures, percent germination of some resistant accessions was higher after 12 or 24 h, but germination of all accessions was similar at later times. HPLC analysis revealed that seeds from resistant accessions contained about 2-fold higher free levels of branched chain amino acids than seeds from susceptible accessions. The results indicate that mutations conferring resistance to sulfonylurea herbicides in these kochia accessions may concomitantly reduce or abolish acetolactate synthase sensitivity to normal feedback inhibition patterns, resulting in elevated levels of branched chain amino acids available for cell division and growth during early germination.

Fun with Mutants: Applying Genetic Methods to Problems of Weed Physiology

Weed Science ◽  
1991 ◽  
Vol 39 (3) ◽  
pp. 489-496 ◽  
Author(s):  
Michael L. Christianson
Keyword(s):  
Amino Acids ◽  
Case History ◽  
Potential Problem ◽  
Plant Cells ◽  
Acetolactate Synthase ◽  
Branched Chain Amino Acids ◽  
Successful Development ◽  
Amino Butyric Acid ◽  
Branched Chain ◽  
Whole Plants

Genetics can be a powerful adjunct to just about any kind of physiological study, including weed physiology or weed/herbicide interactions. Making, mapping, and reverting mutations is simple and straightforward. Making mutants can be as simple as isolating variant individuals from the “wild”, as uncomplicated as doing seed mutagenesis in your laboratory, or as sneaky as recovering mutants as sectors in whole plants. The overall principles for successful development of a protocol for seed mutagenesis of weeds are described and potential problem areas noted. These generalities are illustrated with a specific case history, that of chlorsulfuron. Although chlorsulfuron is accurately described as an inhibitor of the synthesis of branched chain amino acids, careful physiological examination suggests that it kills plant cells, not by starvation for amino acids, but by active toxicity of a metabolite, α-amino butyric acid, produced from a precursor available for diversion in cells with inhibited acetolactate synthase (EC 4.1.3.18, ALS). The story of dominant resistance due to an altered ALS enzyme is well known; analysis using additional mutants fleshes out the story of how chlorsulfuron works. Such analysis has the potential to help unravel other problems in weed physiology.

scholarly journals The adaptation in musle oxidation of leucine to dietary protein and energy intake

1974 ◽  
Vol 31 (3) ◽  
pp. 333-342 ◽  
Author(s):  
R. D. Sketcher ◽  
E. B. Fern ◽  
W. P. T. James
Keyword(s):  
Amino Acids ◽  
Enzyme Activity ◽  
Dehydrogenase Activity ◽  
Liver Enzyme ◽  
Branched Chain Amino Acids ◽  
Metabolizable Energy ◽  
Muscle Enzyme ◽  
Oxidation Activity ◽  
Branched Chain

1. Female hooded rats (65g) were maintained on a high-protein (HP) or low-protein (LP) diet for 2 weeks (ratio, energy supplied by utilizable protein: total metabolizable energy 10 and 3.5 respectively) and the oxidation of both L- and DL-[1-14C]leucine in vivo was measured in the fed and fasted animal.2. Oxidation of leucine in vivo was reduced in the animals given the LP diet. Fasting caused an increase in the oxidation of the branched-chain amino acids.3. Leucine-α-oxoglutarate transaminase (EC 2.6.1.6) and α-ketoisocaproic acid dehydrogenase were measured in both liver and gastrocnemius muscle from rats fed on the HP or LP diet. Enzymes were also assayed after a 48 h fast in a group of animals previously maintained on the HP diet.4. The LP diet led to a fall in muscle dehydrogenase activity without any alterations in liver enzyme activity. Fasting also reduced muscle dehydrogenase activity but increased liver dehydrogenase activity.5. The presence of a dehydrogenase in muscle and its ability to adapt to dietary stress at a time when the liver enzyme is unaffected suggests that muscle is the most important site for control of leucine oxidation.6. Transaminase activity in muscle rose in the LP and fasted animals but the activity in liver was unchanged.7. Oxidation, incorporation into protein of [U-14C]leucine and the pool sizes of free leucine in plasma and in the extensor digitorum longus muscles were measured. The rats were maintained under the feeding conditions described above. The ability of incubated muscles to incorporate [14C]leucine into protein in both the fasted animals and those fed on the LP diet was reduced. Oxidation of leucine in muscle was reduced in protein deficiency but there was little change in the evolution of 14CO2 from [U-14C]leucine on fasting.8. The increase in pool size of free leucine in fasted animals is probably important in determining its rate of oxidation in muscle, as 14CO2 production was maintained despite falling activities of the dehydrogenase enzyme activity. The muscle enzyme accounted for 90% of the calculated body capacity for oxidation; activity in liver is insufficient to deal with normal rates of oxidation. Muscle enzyme is normally in excess of that required for the oxidation of branched-chain amino acids.

Rapid Diagnosis of Als/Ahas-Resistant Weeds

1993 ◽  
Vol 7 (2) ◽  
pp. 519-524 ◽  
Author(s):  
B. Clifford Gerwick ◽  
Linda C. Mireles ◽  
Robert J. Eilers
Keyword(s):  
Amino Acids ◽  
Acetolactate Synthase ◽  
Branched Chain Amino Acids ◽  
Rapid Diagnosis ◽  
Acetohydroxyacid Synthase ◽  
Number Of Species ◽  
Apical Leaf ◽  
Diagnosis Method ◽  
Branched Chain ◽  
Leaf Disks

A method to rapidly identify acetolactate synthase/acetohydroxyacid synthase (ALS/AHAS)-resistant weeds is described based upon the differential accumulation of acetoin in the presence and absence of an ALS/AHAS inhibitor herbicide. Acetoin accumulation is induced by inhibition of ketol-acid reductoisomerase (KARI), the enzyme immediately following ALS/AHAS in the biosynthesis of branched-chain amino acids. Inhibition of ALS/AHAS prevents the build up of acetoin and forms the basis for distinguishing between sensitive and resistant biotypes. A new inhibitor of KARI, 1,1-cyclopropanedicarboxylic acid (CPCA), is described and was found to cause acetoin accumulation in velvetleaf leaf disks over the concentration range of 2 to 100 000 μM. In the presence of CPCA, a number of species important to monitor for ALS/AHAS resistance were found to accumulate acetoin at rates sufficient for resistance diagnosis in 2 to 8 h. In velvetleaf, the youngest apical leaf was found to be the most active in acetoin accumulation. The resistance diagnosis method was validated by clearly distinguishing between imazaquin-sensitive and imazaquin-resistant cocklebur biotypes.

The Weight Loss Effects of Branched Chain Amino Acids and Vitamin B6: A Randomized Controlled Trial on Obese and Overweight Women

2018 ◽  
Vol 88 (1-2) ◽  
pp. 80-89 ◽  
Author(s):  
Zahra Shakibay Novin ◽  
Saeed Ghavamzadeh ◽  
Alireza Mehdizadeh
Keyword(s):  
Amino Acids ◽  
Weight Loss ◽  
Body Composition ◽  
Vitamin B6 ◽  
Controlled Trial ◽  
Density Lipoprotein ◽  
Branched Chain Amino Acids ◽  
Model Assessment ◽  
Waist To Hip Ratio ◽  
Branched Chain

Abstract. Branched chain amino acids (BCAA), with vitamin B6 have been reported to improve fat metabolism and muscle synthesis. We hypothesized that supplementation with BCAA and vitamin B6 would result in more weight loss and improve body composition and blood markers related to cardiovascular diseases. Our aim was to determine whether the mentioned supplementation would affect weight loss, body composition, and cardiovascular risk factors during weight loss intervention. To this end, we performed a placebo-controlled randomized clinical trial in 42 overweight and obese women (BMI = 25–34.9 kg/m2). Taking a four-week moderate deficit calorie diet (–500 kcal/day), participants were randomized to receive BCAA (6 g/day) with vitamin B6 (40 mg/day) or placebo. Body composition variables measured with the use of bioelectrical impedance analysis, homeostatic model assessment, and plasma insulin, Low density lipoprotein, High density lipoprotein, Total Cholesterol, Triglyceride, and fasting blood sugar were measured. The result indicated that, weight loss was not significantly affected by BCAA and vitamin B6 supplementation (–2.43 ± 1.02 kg) or placebo (–1.64 ± 1.48 kg). However, significant time × treatment interactions in waist to hip ratio (P = 0.005), left leg lean (P = 0.004) and right leg lean (P = 0.023) were observed. Overall, supplementation with BCAA and vitamin B6 could preserve legs lean and also attenuated waist to hip ratio.

Branched chain amino acids decrease top-down event-related potentials in healthy subjects

2007 ◽  
Vol 40 (05) ◽  
Author(s):  
AH Neuhaus ◽  
TE Goldberg ◽  
Y Hassoun ◽  
JA Bates ◽  
KW Nassauer ◽  
...  
Keyword(s):  
Amino Acids ◽  
Healthy Subjects ◽  
Event Related Potentials ◽  
Branched Chain Amino Acids ◽  
Top Down ◽  
Related Potentials ◽  
Branched Chain
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