Synergistic Binding of the Halide and Cationic Prime Substrate of l-Lysine 4-Chlorinase, BesD, in Both Ferrous and Ferryl States.

An aliphatic halogenase requires four substrates: 2-oxoglutarate (2OG), halide (Cl or Br), the halogenation target ("prime substrate"), and dioxygen. In well-studied cases, the three nongaseous substrates must bind to activate the enzyme's Fe(II) cofactor for efficient capture of O. Halide, 2OG, and (lastly) O all coordinate directly to the cofactor to initiate its conversion to a -halo-oxo-iron(IV) (haloferryl) complex, which abstracts hydrogen (H) from the non-coordinating prime substrate to enable radicaloid carbon-halogen coupling.

Synergistic Binding of the Halide and Cationic Prime Substrate of the l-Lysine 4-Chlorinase, BesD, in Both Ferrous and Ferryl States.

An aliphatic halogenase requires four substrates: 2-oxoglutarate (2OG), halide (Cl or Br ), the halogenation target ("prime substrate"), and dioxygen. In well-studied cases, the three non-gaseous substrates must bind to activate the enzyme's Fe(II) cofactor for efficient capture of O . Halide, 2OG, and (lastly) O all coordinate directly to the cofactor to initiate its conversion to a -halo-oxo-iron(IV) (haloferryl) complex, which abstracts hydrogen (H•) from the non-coordinating prime substrate to enable radicaloid carbon-halogen coupling.

Methods for Biophysical Characterization of SznF, a Member of the Heme-Oxygenase-Like Diiron Oxidase/Oxygenase Superfamily.

Nonheme diiron enzymes harness the chemical potential of oxygen to catalyze challenging reactions in biology. In their resting state, these enzymes have a diferrous cofactor that is coordinated by histidine and carboxylate ligands. Upon exposure to oxygen, the cofactor oxidizes to its diferric state forming a peroxo- adduct, capable of catalyzing a wide range of oxidative chemistries such as desaturation and heteroatom oxidation.

Substrate-Triggered μ-Peroxodiiron(III) Intermediate in the 4-Chloro-l-Lysine-Fragmenting Heme-Oxygenase-like Diiron Oxidase (HDO) BesC: Substrate Dissociation from, and C4 Targeting by, the Intermediate.

The enzyme BesC from the -thynyl-l-erine biosynthetic pathway in fragments 4-chloro-l-lysine (produced from l-Lysine by BesD) to ammonia, formaldehyde, and 4-chloro-l-allylglycine and can analogously fragment l-Lys itself. BesC belongs to the emerging family of O-activating non-heme-diiron enzymes with the "heme-oxygenase-like" protein fold (HDOs). Here, we show that the binding of l-Lys or an analogue triggers capture of O by the protein's diiron(II) cofactor to form a blue μ-peroxodiiron(III) intermediate analogous to those previously characterized in two other HDOs, the olefin-installing fatty acid decarboxylase, UndA, and the guanidino--oxygenase domain of SznF.

Effects of stimulant medication on divergent and convergent thinking tasks related to creativity in adults with attention-deficit hyperactivity disorder.

Rationale: Common pharmacological treatments for attention-deficit hyperactivity disorder (ADHD) are central nervous system stimulants acting as norepinephrine-dopamine reuptake inhibitors. The noradrenergic and dopaminergic systems have been shown to impact performance on tasks assessing creativity. Some previous studies suggest higher performance on creativity tasks in ADHD.

Structure and assembly of the diiron cofactor in the heme-oxygenase-like domain of the -nitrosourea-producing enzyme SznF.

In biosynthesis of the pancreatic cancer drug streptozotocin, the tridomain nonheme-iron oxygenase SznF hydroxylates and ' of -methyl-l-arginine before oxidatively rearranging the triply modified guanidine to the -methyl--nitrosourea pharmacophore. A previously published structure visualized the monoiron cofactor in the enzyme's C-terminal cupin domain, which promotes the final rearrangement, but exhibited disorder and minimal metal occupancy in the site of the proposed diiron cofactor in the hydroxylating heme-oxygenase-like (HO-like) central domain. We leveraged our recent observation that the -oxygenating µ-peroxodiiron(III/III) intermediate can form in the HO-like domain after the apo protein self-assembles its diiron(II/II) cofactor to solve structures of SznF with both of its iron cofactors bound.

A Peroxodiiron(III/III) Intermediate Mediating Both -Hydroxylation Steps in Biosynthesis of the -Nitrosourea Pharmacophore of Streptozotocin by the Multi-domain Metalloenzyme SznF.

The alkylating warhead of the pancreatic cancer drug streptozotocin (SZN) contains an -nitrosourea moiety constructed from -methyl-l-arginine (l-NMA) by the multi-domain metalloenzyme SznF. The enzyme's central heme-oxygenase-like (HO-like) domain sequentially hydroxylates N and N' of l-NMA. Its C-terminal cupin domain then rearranges the triply modified arginine to -hydroxy-methyl--nitroso-l-citrulline, the proposed donor of the functional pharmacophore.

Biochemical and Structural Characterization of XoxG and XoxJ and Their Roles in Lanthanide-Dependent Methanol Dehydrogenase Activity.

Lanthanide (Ln)-dependent methanol dehydrogenases (MDHs) have recently been shown to be widespread in methylotrophic bacteria. Along with the core MDH protein, XoxF, these systems contain two other proteins, XoxG (a c-type cytochrome) and XoxJ (a periplasmic binding protein of unknown function), about which little is known. In this work, we have biochemically and structurally characterized these proteins from the methyltroph Methylobacterium extorquens AM1.

Structures of Class Id Ribonucleotide Reductase Catalytic Subunits Reveal a Minimal Architecture for Deoxynucleotide Biosynthesis.

Class I ribonucleotide reductases (RNRs) share a common mechanism of nucleotide reduction in a catalytic α subunit. All RNRs initiate catalysis with a thiyl radical, generated in class I enzymes by a metallocofactor in a separate β subunit. Class Id RNRs use a simple mechanism of cofactor activation involving oxidation of a Mn cluster by free superoxide to yield a metal-based MnMn oxidant.