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Tetrahydrobiopterin Scavenges Superoxide in Dopaminergic Neurons*
It is hypothesized that tetrahydrobiopterin (BH4) protects dopaminergic neurons from ordinary oxidative stresses generated by dopamine and its metabolites and that environmental insults or genetic defects may disrupt this intrinsic capacity of dopamine neurons and contribute to their degeneration in Parkinson's disease.
Troponin Regulatory Function and Dynamics Revealed by H/D Exchange-Mass Spectrometry*
Detailed mapping of the dynamic properties of cardiac troponin using amide hydrogen exchange-mass spectrometry suggests that cardiac Troponin switches between alternative sets of intramolecular interactions, similar to previous intermediate resolution x-ray data of skeletal muscle trop onin.
Purification and Cloning of the GTP Cyclohydrolase I Feedback Regulatory Protein, GFRP*
GFRP is widely expressed and may play a role in regulating not only phenylalanine metabolism in the liver, but also the production of biogenic amine neurotransmitters as well as nitric oxide synthesis.
Low Temperature Dynamic Mapping Reveals Unexpected Order and Disorder in Troponin*
The dynamic behavior of the Ca2+-saturated cardiac troponin core domain was mapped in detail at 10 °C, using H/D exchange-mass spectrometry to indicate that, in solution, the regulatory subdomain of cardiac Troponin is mobile relative to the remainder of troponIn, suggesting that trop onin is an unusually mobile protein under physiological conditions.
Structure-function relationships in the cysteine proteinases actinidin, papain and papaya proteinase Ω : three-dimensional structure of papaya proteinase Ω deduced by knowledge-based modelling and
1. A model of the three-dimensional structure of papaya proteinase omega, the most basic cysteine proteinase component of the latex of papaya (Carica papaya), was built from its amino acid sequence
Differences in the chemical and catalytic characteristics of two crystallographically 'identical' enzyme catalytic sites. Characterization of actinidin and papain by a combination of pH-dependent
The earlier conclusion that the acylation of papain depends on two protonic dissociations each with pKa approx.
The interplay of electrostatic fields and binding interactions determining catalytic-site reactivity in actinidin. A possible origin of differences in the behaviour of actinidin and papain.
The P2/S2 contacts substantially improve enzyme-ligand binding, and greatly enhance the contribution to reactivity of the hydronic state bounded by pKa 3 and pKa 5, such that the major rate optimum occurs at pH 4 instead of at pH 2.8-2.9, and reveal the kinetic influence of a pKa approx.
Recombinant human phenylalanine hydroxylase: novel regulatory and structural properties.
The recombinant human liver phenylalanine hydroxylase is in an activated state and is less sensitive than the rat liver enzyme to stimulation by lysolecithin when tryptophan is the substrate, and the ability of 7-tetrahydrobiopterin (7-BH4) to substitute for the natural cofactor tetrahydrobopterin has been studied in vitro.
Preferential Resistance of Dopaminergic Neurons to the Toxicity of Glutathione Depletion Is Independent of Cellular Glutathione Peroxidase and Is Mediated by Tetrahydrobiopterin
It is suggested that tetrahydrobiopterin (BH4) functions as a complementary antioxidant to the glutathione/glutathione peroxidase system and that changes in BH4 levels may contribute to the pathogenesis of PD.