scholarly journals ENZYME FORMATION IN HIGHER-PLANT TISSUES. DEVELOPMENT OF INVERTASE AND ASCORBATE-OXIDASE ACTIVITIES IN MATURE STORAGE TISSUE OF HELIANTHUS TUBEROSUS L

1965 ◽  
Vol 95 (2) ◽  
pp. 403-410 ◽  
Author(s):  
J EDELMAN ◽  
MA HALL
Keyword(s):  
Ascorbate Oxidase ◽  
Plant Tissues ◽  
Helianthus Tuberosus ◽  
Higher Plant ◽  
Storage Tissue ◽  
Enzyme Formation

Adenylate Kinase from Maize Leaves: True Substrates, Inhibition by P1 , P5-di(adenosine-5′) pentaphosphate and Kinetic Mechanism

1990 ◽  
Vol 45 (6) ◽  
pp. 607-613 ◽  
Author(s):  
Leszek A. Kleczkowski ◽  
Douglas D. Randall ◽  
Warren L. Zahler
Keyword(s):  
Adenylate Kinase ◽  
Kinetic Studies ◽  
Kinetic Mechanism ◽  
Reverse Reaction ◽  
Plant Tissues ◽  
Forward Reaction ◽  
Higher Plant ◽  
Maize Leaves ◽  
Variable Substrate ◽  
Free Magnesium

Abstract Purified maize leaf adenylate kinase (AK) was shown to use one molecule each of free ADP and Mg-ADP as well as free AM P and Mg-ATP as substrates in the forward and reverse reaction, respectively. This was deduced from substrate kinetic studies which were carried out under conditions of strictly defined concentrations of free and Mg-complexed adenylate species and under controlled free magnesium levels. Apparent Km values of the substrates of AK were 3 and 6 μM for ADP and Mg-ADP, respectively (forward reaction), and 69 and 25 μM for free AMP and Mg-ATP, respectively (reverse reaction). The enzyme was competitively inhibited by P1,P5-di(adenosine-5′)pentaphosphate (Ap5A), a bisubstrate analog of AK reaction, with apparent Ki values in the range of 11 -80 nM , depending on variable substrate. Substrate kinetic studies and inhibition patterns with Ap5A suggested a sequential random kinetic mechanism in both directions of the reaction. These properties of a higher plant AK are similar or analogous to those previously established for the enzyme from yeast and non-plant tissues.

Extraction, Gas-Liquid Chromatographic Detection, and Quantitation of Hexachlorophene Residues from Plant Tissues High in Lipid Content

1977 ◽  
Vol 60 (5) ◽  
pp. 1087-1092
Author(s):  
Oscar W Van Auken ◽  
Michael Hulse ◽  
Constance L Durocher
Keyword(s):  
Silica Gel ◽  
Lipid Content ◽  
Neutral Lipids ◽  
Parent Compound ◽  
Plant Tissues ◽  
Storage Tissue ◽  
Glass Column ◽  
Chromatographic Detection ◽  
Liquid Chromatographic ◽  
Plant Storage

Abstract A method has been developed for the extraction, cleanup, derivatization, detection, and quantitation of hexachlorophene (HCP) residues from 2 types of plant storage tissue high in lipid content. Wet soybean or peanut tissue was homogenized and extracted with ethyl ether and chromatographed on silica gel to remove the neutral lipids. The cleaned up sample was methylated with diazomethane and the dimethoxyhexachlorophene was eluted from a second silica gel column and chromatographed on a 6′ glass column packed with 3% OV-1 or 3% SE-30 on Gas-Chrom Q. The instrument detection limit for the 63Ni electron capture detector was <0.1 ng for dimethoxyhexachlorophene and about 1 ppb for HCP residue in plant issue. Recovery of 10–420 ppb HCP added to tissue averaged 90.9±5.7%. Interfering substances were removed, column life was increased, peak sharpness was increased, and tailing of the parent compound was decreased by using appropriate column chromatography.

OCCURRENCE AND PROPERTIES OF L-AMINOACID:2-GLYOXYLATE AMINOTRANSFERASE IN PLANTS

1965 ◽  
Vol 43 (4) ◽  
pp. 495-506 ◽  
Author(s):  
E. A. Cossins ◽  
S. K. Sinha
Keyword(s):  
Enzyme System ◽  
Intracellular Localization ◽  
Plant Tissues ◽  
Amino Group ◽  
Transaminase Activity ◽  
Higher Plant ◽  
Amino Donor ◽  
Glyoxylate Aminotransferase

Extracts prepared from a variety of higher plant tissues have been examined for L-aminoacid:2-glyoxylate aminotransferase (glyoxylate transaminase) activity. This enzyme has been detected in extracts prepared from sunflower cotyledons, corn coleoptiles, mature pea leaves, and carrot storage tissues.Measurement of glyoxylate transaminase activity was based on ability of the extracts to convert glyoxylate- 1,2-C14 to glycine-1,2-C14 in the presence of a suitable amino group donor.Properties of this enzyme system, including amino donor requirements, inhibition, pH optima, and reversibility, have been studied using extracts prepared from mature pea leaves. In sunflower cotyledons, glyoxylate transaminase activity decreased during germination. Studies of the intracellular localization of this enzyme have shown that glyoxylate transamination occurs mainly in the cytoplasm.

A reliable method for the estimation of DNA in higher plant tissues

1976 ◽  
Vol 71 (1) ◽  
pp. 308-312 ◽  
Author(s):  
J. Singh ◽  
D. Siminovitch
Keyword(s):  
Reliable Method ◽  
Plant Tissues ◽  
Higher Plant
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