Characterization of Phosphoenolpyruvate Carboxykinase from Pineapple Leaves Ananas comosus (L.) Merr.

ABSTRACT Phosphoenolpyruvate carboxykinase (PCK), which catalyzes the nucleotide-dependent, reversible decarboxylation of oxaloacetate to yield phosphoenolpyruvate and CO2, is one of the important enzymes in the interconversion between C3 and C4 metabolites. This study focused on the first characterization of the enzymatic properties and expression profile of an archaeal PCK from the hyperthermophilic archaeon Thermococcus kodakaraensis (Pck Tk ). Pck Tk showed 30 to 35% identities to GTP-dependent PCKs from mammals and bacteria but was located in a branch distinct from that of the classical enzymes in the phylogenetic tree, together with other archaeal homologs from Pyrococcus and Sulfolobus spp. Several catalytically important regions and residues, found in all known PCKs irrespective of their nucleotide specificities, were conserved in Pck Tk . However, the predicted GTP-binding region was unique compared to those in other GTP-dependent PCKs. The recombinant Pck Tk actually exhibited GTP-dependent activity and was suggested to possess dual cation-binding sites specific for Mn2+ and Mg2+. The enzyme preferred phosphoenolpyruvate formation from oxaloacetate, since the Km value for oxaloacetate was much lower than that for phosphoenolpyruvate. The transcription and activity levels in T. kodakaraensis were higher under gluconeogenic conditions than under glycolytic conditions. These results agreed with the role of Pck Tk in providing phosphoenolpyruvate from oxaloacetate as the first step of gluconeogenesis in this hyperthermophilic archaeon. Additionally, under gluconeogenic conditions, we observed higher expression levels of Pck Tk on pyruvate than on amino acids, implying that it plays an additional role in the recycling of excess phosphoenolpyruvate produced from pyruvate, replacing the function of the anaplerotic phosphoenolpyruvate carboxylase that is missing from this archaeon.

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Characterization of the cAMP responsive elements from the genes for the alpha-subunit of glycoprotein hormones and phosphoenolpyruvate carboxykinase (GTP). Conserved features of nuclear protein binding between tissues and species.

Journal of Biological Chemistry ◽

10.1016/s0021-9258(19)77697-2 ◽

1988 ◽

Vol 263 (36) ◽

pp. 19740-19747

Author(s):

J A Bokar ◽

W J Roesler ◽

G R Vandenbark ◽

D M Kaetzel ◽

R W Hanson ◽

...

Keyword(s):

Protein Binding ◽

Phosphoenolpyruvate Carboxykinase ◽

Nuclear Protein ◽

Alpha Subunit ◽

Glycoprotein Hormones

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Extraction, Partial Purification and Characterization of Bromelain from Pineapple (Ananas Comosus) Crown, Core and Peel Waste

Brazilian Archives of Biology and Technology ◽

10.1590/1678-4324-2021200639 ◽

2021 ◽

Vol 64 ◽

Author(s):

Anum Gul ◽

Maryam Siddiqui ◽

Habiba Arain ◽

Sadaf Khan ◽

Hanzala Khan ◽

...

Keyword(s):

Ananas Comosus ◽

Partial Purification ◽

Purification And Characterization

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ANTIOXIDANT ACTIVATION OF ETHANOL EXTRACTS FROM PINEAPPLE LEAVES (Ananas comosus) AT TAC CAU REGION, KIEN GIANG PROVINCE

Scientific Journal of Tra Vinh University ◽

10.35382/18594816.1.40.2020.615 ◽

2020 ◽

Vol 1 (40) ◽

pp. 39-49

Author(s):

Hau Thu Nguyen Thi ◽

Dung Nhan Tran ◽

Ba Van Huynh ◽

Quyen Ngoc Thi ◽

An Tran Hoang Bui ◽

...

Keyword(s):

Nutritional Value ◽

Extraction Efficiency ◽

Raw Materials ◽

Ananas Comosus ◽

Total Polyphenol ◽

Waste Products ◽

Resistance To Oxidation ◽

Ethanol Extracts ◽

Pharmaceutical Production ◽

Pineapple Leaves

Pineapple (Ananas comosus) is a kind of fruit with high nutritional value. This study investigated the resistance to oxidation DPPH (2,2-Diphenyl-1picrylhydrazyl (free radical) and deionized Fe3+ of ethanol extracts from theleaves (leaves grow on stems) and crown (crown of scale leaves) of pineapples. Study of high extraction efficiency in 99,5% ethanol solvent, mixing ratio between samples with the solvent is 1 : 4, combined ultrasonic wave with a capacity of 120 Walt within 72 hours. The total polyphenol content in all treatments was high: leave sample (140,9 ± 2,86 mg GAE/g) and crown sample (204,6 ± 0,29 mg GAE/g). The results showed thatDPPH oxidation resistance and deionized Fe3+ were: crown (IC50 = 254,74 ± 1,55 mg/mL và 908,12 ± 9,35 mg/mL) higher than leaves (IC50 = 977,78 ± 30,27m mg/mL and 2156,62 ± 23,03 mg/mL). Theresearch has found that the use of waste products from pineapple peels with antioxidant capacity could be added to potential raw materials in the field of pharmaceutical production.

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