Dataset Information

Phosphoenolpyruvate carboxylase from the crassulacean plant Bryophyllum fedtschenkoi Hamet et Perrier. Purification, molecular and kinetic properties.

ABSTRACT: Phosphoenolpyruvate carboxylase from the Crassulacean plant Bryophyllum fedtschenkoi has been purified to homogenetity by DEAE-cellulose treatment, (NH4)2SO4 fractionation,, and chromatography on DEAE-cellulose and hydroxyapatite. Poly(ethylene glycol) is required in the extraction medium to obtain maximum enzyme activity. The purified enzyme has a specific activity of about 26 units/mg of protein at 25 degrees C. It gives a single band on sodium dodecyl sulphate/polyacrylamide-gel electrophoresis, corresponding to a mol.wt. of 105,000, and gives a single band on non-denaturing gel electrophoresis at pH8.4. Cross-linking studies at pH8.0 indicate that the subunit structure is tetrameric but that the dimer may also be an important unit of polymerization. Gel filtration results at pH6.7 confirm that the native enzyme is tetrameric with a concentration-dependent dissociation to a dimer. The kinetic behaviour is characterized by (i) relatively small variations in maximum velocity between pH5.5 and 9.0 with a double optimum, (ii) a reversible temperature-dependent inactivation between 30 and 45 degrees C, (iii) inhibition by malate, which is pH-sensitive, and (iv) almost Michaelis-Menten behaviour with phosphoenolpyruvate as the varied ligand but sigmoidal behaviour under suitable conditions with malate as the varied ligand. The findings are related to other studies to the possible role phosphoenolpyruvate carboxylase in controlling a circadian rhythm of CO2 fixation.

SUBMITTER: Jones R

PROVIDER: S-EPMC1186084 | biostudies-other | 1978 Nov

REPOSITORIES: biostudies-other

ACCESS DATA

Similar Datasets

Project description:Phosphoenolpyruvate carboxylase (PEPC) is an important enzyme in plants, which regulates carbon flow through the TCA cycle and controls protein and oil biosynthesis. Although it is important, there is little research on PEPC in cotton, the most important fiber crop in the world. In this study, a total of 125 PEPCs were identified in 15 Gossypium genomes. All PEPC genes in cotton are divided into six groups and each group generally contains one PEPC member in each diploid cotton and two in each tetraploid cotton. This suggests that PEPC genes already existed in cotton before their divergence. There are additional PEPC sub-groups in other plant species, suggesting the different evolution and natural selection during different plant evolution. PEPC genes were independently evolved in each cotton sub-genome. During cotton domestication and evolution, certain PEPC genes were lost and new ones were born to face the new environmental changes and human being needs. The comprehensive analysis of collinearity events and selection pressure shows that genome-wide duplication and fragment duplication are the main methods for the expansion of the PEPC family, and they continue to undergo purification selection during the evolutionary process. PEPC genes were widely expressed with temporal and spatial patterns. The expression patterns of PEPC genes were similar in G. hirsutum and G. barbadense with a slight difference. PEPC2A and 2D were highly expressed in cotton reproductive tissues, including ovule and fiber at all tested developmental stages in both cultivated cottons. However, PEPC1A and 1D were dominantly expressed in vegetative tissues. Abiotic stress also induced the aberrant expression of PEPC genes, in which PEPC1 was induced by both chilling and salinity stresses while PEPC5 was induced by chilling and drought stresses. Each pair (A and D) of PEPC genes showed the similar response to cotton development and different abiotic stress, suggesting the similar function of these PEPCs no matter their origination from A or D sub-genome. However, some divergence was also observed among their origination, such as PEPC5D was induced but PEPC5A was inhibited in G. barbadense during drought treatment, suggesting that a different organized PEPC gene may evolve different functions during cotton evolution. During cotton polyploidization, the homologues genes may refunction and play different roles in different situations.

Dataset Information

Phosphoenolpyruvate carboxylase from the crassulacean plant Bryophyllum fedtschenkoi Hamet et Perrier. Purification, molecular and kinetic properties.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets