Kyungpook National University

About: Kyungpook National University is a education organization based out in Daegu, South Korea. It is known for research contribution in the topics: Population & Catalysis. The organization has 20497 authors who have published 42107 publications receiving 834608 citations.

Trapping H- Bound to the Nitrogenase FeMo-Cofactor Active Site during H2 Evolution: Characterization by ENDOR Spectroscopy

Abstract: We here show that the iron−molybdenum (FeMo)-cofactor of the nitrogenase α-70Ile molybdenum−iron (MoFe) protein variant accumulates a novel S = 1/2 state that can be trapped during the reduction of protons to H2. 1,2H-ENDOR measurements disclose the presence of two protons/hydrides (H+/-) whose hyperfine tensors have been determined from two-dimensional field-frequency 1H ENDOR plots. The two H+/- have large isotropic hyperfine couplings, Aiso≈ 23 MHz, which shows they are bound to the cofactor. The favored analysis for these plots indicates that the two H+/- have the same principal values, which indicates that they are chemically equivalent. The tensors are further related to each other by a permutation of the tensor components, which indicates an underlying symmetry of binding relative to the cofactor. At present, no model for the structure of the iron−molybdenum (FeMo)-cofactor in the S = 1/2 state trapped during the reduction of H+ can be shown unequivocally to satisfy all of the constraints generated...

Cognitive Effects of Antiepileptic Drugs

Abstract: Antiepileptic drugs (AEDs) can adversely affect cognitive function by suppressing neuronal excitability or enhancing inhibitory neurotransmission. The main cognitive effects of AEDs are impaired attention, vigilance, and psychomotor speed, but secondary effects can manifest on other cognitive functions. Although the long-term use of AEDs can obviously elicit cognitive dysfunction in epilepsy patients, their cognitive effects over short periods of up to a year are inconclusive due to methodological problems. In general, the effects on cognition are worse for older AEDs (e.g., phenobarbital) than for placebo, nondrug condition, and newer AEDs. However, topiramate is the newer AED that has the greatest risk cognitive impairment irrespective of the comparator group. Since the cognitive impact of AEDs can be serious, clinicians should be alert to adverse events by evaluating cognitive function using screening tests. Adverse cognitive events of AEDs can be avoided by slow titration to the lowest effective dosage and by avoiding polytherapy.