The reaction of alternate oxidants with cytochrome P450BM3 and mutants generates spectrally detectable, high valent iron intermediates

"The Cytochrome P450 family serves as the forefront for xenobiotic metabolism in the human body. An understanding of the mechanism behind this enzyme family is a necessity for later research in the areas of pharmaceuticals and biochemistry. It has been observed by previous researchers that the transient species compound I, a highly reactive &#x03C0-cation radical intermediate, is able to be viewed with P450cam and other heme containing proteins with subjection to various oxidant compounds such as m-CPBA or peracetic acid. In this study Cytochrome P450BM3 and its' heme domain, P450BMH, has been reacted with various oxidant compounds to show evidence of this compound I intermediate by diode array spectrophotometry and electron paramagnetic resonance spectroscopy."--Abstract from author supplied metadata

Generating a theoretical base for restructuring curriculum content

The purpose of this study is to contribute to an ongoing effort among a number of contemporary curriculum theorists to generate a theoretical base for restructuring' curriculum content. The study is divided into a Prologue, two Chapters, and an Epilogue. PROLOGUE confronts the significant metatheoretical cal problems that are are raised simply by the articulation of this project. In the course of asking "What kind of research strategies, consonant with this intention, are appropriate for educators in North America?" the study reviews the metatheoretical considerations that have led contemporary curriculum theorists to frame such a question. Two avenues of approach that have emerged from such considerations are identified--a personal change position that involves a restructuring of individual consciousness, and a social change position that is oriented towards a restructuring of the ensemble of social relationships. The potentials of these two strategies are explored, and an argument is made for the development of a way of speaking and acting that honors the significance of both

Spectroscopic investigations of intermediates in the reaction of cytochrome P450BM3–F87G with surrogate oxygen atom donors

Rapid mixing of substrate-free ferric cytochrome P450BM3–F87G with m-chloroperoxybenzoic acid (mCPBA) resulted in the sequential formation of two high-valent intermediates. The first was spectrally similar to compound I species reported previously for P450CAM and CYP 119 using mCPBA as an oxidant, and it featured a low intensity Soret absorption band characterized by shoulder at 370 nm. This is the first direct observation of a P450 compound I intermediate in a type II P450 enzyme. The second intermediate, which was much more stable at pH values below 7.0, was characterized by an intense Soret absorption peak at 406 nm, similar to that seen with P450CAM [T. Spolitak, J.H. Dawson, D.P. Ballou, J. Biol. Chem. 280 (2005) 20300–20309]. Double mixing experiments in which NADPH was added to the transient 406 nm-absorbing intermediate resulted in rapid regeneration of the resting ferric state, with the flavins of the flavoprotein domain in their reduced state. EPR results were consistent with this stable intermediate species being a cytochrome c peroxidase compound ES-like species containing a protein-based radical, likely localized on a nearby Trp or Tyr residue in the active site. Iodosobenzene, peracetic acid, and sodium m-periodate also generated the intermediate at 406 nm, but not the 370 nm intermediate, indicating a probable kinetic barrier to accumulating compound I in reactions with these oxidants. The P450 ES intermediate has not been previously reported using iodosobenzene or m-periodate as the oxygen donor

Teleost Growth Factor Independence (Gfi) Genes Differentially Regulate Successive Waves of Hematopoiesis

Growth Factor Independence (Gfi) transcription factors play essential roles in hematopoiesis, differentially activating and repressing transcriptional programs required for hematopoietic stem/progenitor cell (HSPC) development and lineage specification. In mammals, Gfi1a regulates hematopoietic stem cells (HSC), myeloid and lymphoid populations, while its paralog, Gfi1b, regulates HSC, megakaryocyte and erythroid development. In zebrafish, gfi1aa is essential for primitive hematopoiesis; however, little is known about the role of gfi1aa in definitive hematopoiesis or about additional gfi factors in zebrafish. Here, we report the isolation and characterization of an additional hematopoietic gfi factor, gfi1b. We show that gfi1aa and gfi1b are expressed in the primitive and definitive sites of hematopoiesis in zebrafish. Our functional analyses demonstrate that gfi1aa and gfi1b have distinct roles in regulating primitive and definitive hematopoietic progenitors, respectively. Loss of gfi1aa silences markers of early primitive progenitors, scl and gata1. Conversely, loss of gfi1b silences runx-1, c-myb, ikaros and cd41, indicating that gfi1b is required for definitive hematopoiesis. We determine the epistatic relationships between the gfi factors and key hematopoietic transcription factors, demonstrating that gfi1aa and gfi1b join lmo2, scl, runx-1 and c-myb as critical regulators of teleost HSPC. Our studies establish a comparative paradigm for the regulation of hematopoietic lineages by gfi transcription factors.Stem Cell and Regenerative Biolog

1964: Abilene Christian College Bible Lectures - Full Text

LEADERSHIP IN THE CHURCH” Being the Abilene Christian College Annual Bible Lectures 1964 Price: $3.95 Published by ABILENE CHRISTIAN COLLEGE STUDENTS EXCHANGE ACC Station Abilene, Texa