scholarly journals Phosphoenolpyruvate Carboxylase from Spinach Leaf Tissue

1974 ◽  
Vol 53 (6) ◽  
pp. 829-834 ◽  
Author(s):  
S. K. Mukerji ◽  
S. F. Yang
Keyword(s):  
Phosphoenolpyruvate Carboxylase ◽  
Leaf Tissue ◽  
Spinach Leaf

Endogenous biosynthetic precursors of (+)-abscisic acid. VI. Carotenoids and ABA are formed by the ‘non-mevalonate’ triose-pyruvate pathway in chloroplasts

1998 ◽  
Vol 25 (5) ◽  
pp. 507 ◽  
Author(s):  
B.V. Milborrow ◽  
H.-S. Lee
Keyword(s):  
Abscisic Acid ◽  
Leaf Tissue ◽  
Isopentenyl Diphosphate ◽  
Free System ◽  
Cell Free System ◽  
Avocado Fruit ◽  
Intact Chloroplasts ◽  
A Cell ◽  
Spinach Leaf ◽  
Leaf Protoplasts

A cell-free system from avocado fruit which routinely incorporated [14C]mevalonate into ABA (1000 dpm per 5 mL of preparation), and into carotenoids, has now been shown to incorporate [14C]pyruvate even more successfully (1620 dpm). Intact chloroplasts from spinach leaf protoplasts incorporated 2990 dpm of [14C]pyruvate (from 2 x 106 dpm) into ABA compared with 990 dpm from [3-R-5-14C]mevalonate (also from 2 x 106 dpm). The intact chloroplasts also produced [14C]ABA (1575 dpm) when supplied with [14C]isopentenyl diphosphate. This result establishes that the whole pathway of biosynthesis of ABA can occur within chloroplasts. Little [14C]acetate or [14C]alanine was incorporated into ABA by avocado fruit mesocarp. Most of the ABA in leaf tissue now appears to be formed by the triose-pyruvate pathway in chloroplasts and incorporation of [14C]mevalonate occurs after activation in the cytoplasm and importation of a later intermediate into the plastids.

scholarly journals Adenosine diphosphate sulphurylase activity in leaf tissue

1973 ◽  
Vol 133 (3) ◽  
pp. 417-428 ◽  
Author(s):  
Jim N. Burnell ◽  
John W. Anderson
Keyword(s):  
Leaf Tissue ◽  
Thiol Group ◽  
Adenosine Diphosphate ◽  
Ph Optimum ◽  
Elementary Kinetics ◽  
Crude Extracts ◽  
Standard Assay ◽  
Spinach Leaf ◽  
Kinetics Of ◽  
Assay Conditions

1. A new method is described for the assay of ADP sulphurylase. The method involves sulphate-dependent [32P]Pi–ADP exchange; the method is simpler, more sensitive and more direct than the method involving adenosine 5′-sulphatophosphate-dependent uptake of Pi. 2. ADP sulphurylase activity was demonstrated in crude extracts of leaf tissue from a range of plants. Crude spinach extract catalysed the sulphate-dependent synthesis of [32P]ADP from [32P]Pi; spinach extracts did not catalyse sulphate-dependent AMP–Pi, ADP–PPi or ATP–Pi exchange under standard assay conditions. ADP sulphurylase activity in spinach leaf tissue was associated with chloroplasts and was liberated by sonication. 3. Some elementary kinetics of crude spinach leaf and purified yeast ADP sulphurylases in the standard assay are described; addition of Ba2+ was necessary to minimize endogenous Pi–ADP exchange of the yeast enzyme and crude extracts of winter-grown spinach. 4. Spinach leaf ADP sulphurylase was activated by Ba2+ and Ca2+; Mg2+ was ineffective. The yeast enzyme was also activated by Ba2+. The activity of both enzymes decreased with increasing ionic strength. 5. Purified yeast and spinach leaf ADP sulphurylases were sensitive to thiol-group reagents and fluoride. The pH optimum was 8. ATP inhibited sulphate-dependent Pi–ADP exchange. Neither selenate nor molybdate inhibited sulphate-dependent Pi–ADP exchange and crude spinach extracts did not catalyse selenate-dependent Pi–ADP exchange. 6. The presence of ADP sulphurylase activity jeopardizes the enzymic synthesis of adenosine 5′-sulphatophosphate from ATP and sulphate with purified ATP sulphurylase and pyrophosphatase.

Determination of Cysteine and its Accumulation in Spinach Leaf Tissue upon Exposure to Excess Sulfur

1988 ◽  
Vol 133 (4) ◽  
pp. 502-505 ◽  
Author(s):  
Luit J. De Kok ◽  
Fokke Buwalda ◽  
Wiebe Bosma
Keyword(s):  
Leaf Tissue ◽  
Spinach Leaf ◽  
Excess Sulfur

scholarly journals Purification, properties and substrate specificity of adenosine triphosphate sulphurylase from spinach leaf tissue

1972 ◽  
Vol 127 (1) ◽  
pp. 237-247 ◽  
Author(s):  
W. H. Shaw ◽  
J. W. Anderson
Keyword(s):  
Substrate Specificity ◽  
Adenosine Triphosphate ◽  
Leaf Tissue ◽  
Coupled System ◽  
Thiol Group ◽  
Ph Optimum ◽  
Spinach Leaf ◽  
Inorganic Sulphur ◽  
Atp Sulphurylase

1. ATP sulphurylase was purified up to 1000-fold from spinach leaf tissue. Activity was measured by sulphate-dependent [32P]PPi–ATP exchange. The enzyme was separated from Mg2+-requiring alkaline pyrophosphatase (which interferes with the PPi–ATP-exchange assay) and from other PPi–ATP-exchange activities. No ADP sulphurylase activity was detected. 2. Sulphate was the only form of inorganic sulphur that catalysed PPi–ATP exchange; Km (sulphate) was 3.1mm, Km (ATP) was 0.35mm and the pH optimum was 7.5–9.0. The enzyme was insensitive to thiol-group reagents and required either Mg2+ or Co2+ for activity. 3. The enzyme catalysed [32P]PPi–dATP exchange; Km (dATP) was 0.84mm and V (dATP) was 30% of V (ATP). Competition between ATP and dATP was demonstrated. 4. Selenate catalysed [32P]PPi–ATP exchange and competed with sulphate; Km (selenate) was 1.0mm and V (selenate) was 30% of V (sulphate). No AMP was formed with selenate as substrate. Molybdate did not catalyse PPi–ATP exchange, but AMP was formed. 5. Synthesis of adenosine 5′-[35S]sulphatophosphate was demonstrated by coupling purified ATP sulphurylase and Mg2+-dependent alkaline pyrophosphatase (also prepared from spinach) with [35S]sulphate and ATP as substrates; adenosine 5′-sulphatophosphate was not synthesized in the absence of pyrophosphatase. Some parameters of the coupled system are reported.

scholarly journals Adenosine 5′-sulphatophosphate kinase activity in spinach leaf tissue

1973 ◽  
Vol 134 (2) ◽  
pp. 565-579 ◽  
Author(s):  
J. N. Burnell ◽  
J. W. Anderson
Keyword(s):  
Kinase Activity ◽  
Leaf Tissue ◽  
Nucleotidase Activity ◽  
Specific Enzyme ◽  
Ph Optimum ◽  
Spinach Leaf ◽  
Hydrolysis Of ◽  
Isolated Chloroplasts ◽  
Atp Sulphurylase

1. An F−-insensitive 3′-nucleotidase was purified from spinach leaf tissue; the enzyme hydrolysed 3′-AMP, 3′-CMP and adenosine 3′-phosphate 5′-sulphatophosphate but not adenosine 5′-nucleotides nor PPi. The pH optimum of the enzyme was 7.5; Km (3′-AMP) was approx. 0.8mm and Km (3′-CMP) was approx. 3.3mm. 3′-Nucleotidase activity was not associated with chloroplasts. Purified Mg2+-dependent pyrophosphatase, free from F−-insensitive 3′-nucleotidase, catalysed some hydrolysis of 3′-AMP; this activity was F−-sensitive. 2. Adenosine 5′-sulphatophosphate kinase activity was demonstrated in crude spinach extracts supplied with 3′-AMP by the synthesis of the sulphate ester of 2-naphthol in the presence of purified phenol sulphotransferase; purified ATP sulphurylase and pyrophosphatase were also added to synthesize adenosine 5′-sulphatophosphate. Adenosine 5′-sulphatophosphate kinase activity was associated with chloroplasts and was released by sonication. 3. Isolated chloroplasts synthesized adenosine 3′-phosphate 5′-sulphatophosphate from sulphate and ATP in the presence of a 3′-nucleotide; the formation of adenosine 5′-sulphatophosphate was negligible. In the absence of a 3′-nucleotide the synthesis of adenosine 3′-phosphate 5′-sulphatophosphate was negligible, but the formation of adenosine 5′-sulphatophosphate was readily detected. Some properties of the synthesis of adenosine 3′-phosphate 5′-sulphatophosphate by isolated chloroplasts are described. 4. Adenosine 3′-phosphate 5′-sulphatophosphate, synthesized by isolated chloroplasts, was characterized by specific enzyme methods, electrophoresis and i.r. spectrophotometry. 5. Isolated chloroplasts catalysed the incorporation of sulphur from sulphate into cystine/cysteine; the incorporation was enhanced by 3′-AMP and l-serine. It was concluded that adenosine 3′-phosphate 5′-sulphatophosphate is an intermediate in the incorporation of sulphur from sulphate into cystine/cysteine.

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