Publications by authors named "K Gutekunst"
RIBULOSE-1,5-BISPHOSPHATE CARBOXYLASE/OXYGENASE (RUBISCO) is the most abundant enzyme and CO2 bio-sequestration system on Earth. Its in vivo activity is usually determined by 14CO2 incorporation into 3-phosphoglycerate (3PGA). However, the radiometric analysis of 3PGA does not distinguish carbon positions.
View Article and Find Full Text PDFMolecular dynamics of photosynthetic electron flow in a biophotovoltaic system.
Environ Sci Ecotechnol
January 2025
Biophotovoltaics (BPV) represents an innovative biohybrid technology that couples electrochemistry with oxygenic photosynthetic microbes to harness solar energy and convert it into electricity. Central to BPV systems is the ability of microbes to perform extracellular electron transfer (EET), utilizing an anode as an external electron sink. This process simultaneously serves as an electron sink and enhances the efficiency of water photolysis compared to conventional electrochemical water splitting.
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- The oxidative pentose phosphate (OPP) pathway is crucial for generating metabolites and reducing power in cells, with its initial reactions supporting the Calvin-Benson cycle.
- Glucose-6-phosphate dehydrogenase (G6PDH) is the key enzyme in this pathway, regulated by the redox protein OpcA in cyanobacteria, showing different activity based on OpcA's oxidation state.
- Research using cryogenic electron microscopy revealed that OpcA interacts with G6PDH, causing structural changes that fine-tune G6PDH activity depending on the amount of OpcA bound, highlighting a sophisticated regulatory mechanism in the OPP pathway.
Transitioning into and out of dormancy is a crucial survival strategy for many organisms. In unicellular cyanobacteria, surviving nitrogen-starved conditions involves tuning down their metabolism and reactivating it once nitrogen becomes available. Glucose-6-phosphate dehydrogenase (G6PDH), the enzyme that catalyzes the first step of the oxidative pentose phosphate (OPP) pathway, plays a key role in this process.
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- Photosynthetic organisms like cyanobacteria adjust their carbohydrate metabolism based on light conditions, switching between making and breaking down carbohydrates.
- A study on the cyanobacterium Synechocystis sp. PCC 6803 revealed two iso-enzymes of phosphofructokinase (PFK) that uniquely use ADP instead of ATP and have different regulatory mechanisms affecting their activity in light and darkness.
- This finding is significant as it shows a previously undocumented ADP dependence in the PFK-A enzyme family, suggesting a unique evolutionary adaptation in some cyanobacteria and a few related bacteria.