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Full-Text Articles in Medicine and Health Sciences

Anopheles Gambiae Purine Nucleoside Phosphorylase: Catalysis, Structure And Inhibition, Erika Taylor, Agnes Rinaldo-Matthis, Lei Li, Mahmoud Ghanem, Keith Hazleton, M. Belen Cassera, Steven Almo, Vern Schramm Oct 2007

Anopheles Gambiae Purine Nucleoside Phosphorylase: Catalysis, Structure And Inhibition, Erika Taylor, Agnes Rinaldo-Matthis, Lei Li, Mahmoud Ghanem, Keith Hazleton, M. Belen Cassera, Steven Almo, Vern Schramm

Erika A. Taylor, Ph.D.

The purine salvage pathway of Anopheles gambiae, a mosquito that transmits malaria, has been identified in genome searches on the basis of sequence homology with characterized enzymes. Purine nucleoside phosphorylase (PNP) is a target for the development of therapeutic agents in humans and purine auxotrophs, including malarial parasites. The PNP from Anopheles gambiae (AgPNP) was expressed in Escherichia coli and compared to the PNPs from Homo sapiens (HsPNP) and Plasmodium falciparum (PfPNP). AgPNP has kcat values of 54 and 41 s-1 for 2'-deoxyinosine and inosine, its preferred substrates, and 1.0 s-1 for guanosine. However, the chemical step is fast for …


A Role For The Forebrain In Mediating Time-Of-Day Differences In Glucocorticoid Counterregulatory Responses To Hypoglycemia In Rats, Lori M. Gorton, Arshad M. Khan, Maryann Bohland, Graciela Sanchez-Watts, Casey M. Donovan, Alan G. Watts Sep 2007

A Role For The Forebrain In Mediating Time-Of-Day Differences In Glucocorticoid Counterregulatory Responses To Hypoglycemia In Rats, Lori M. Gorton, Arshad M. Khan, Maryann Bohland, Graciela Sanchez-Watts, Casey M. Donovan, Alan G. Watts

Arshad M. Khan, Ph.D.

No abstract provided.


Catecholaminergic Control Of Mitogen-Activated Protein Kinase Signaling In Paraventricular Neuroendocrine Neurons In Vivo And In Vitro: A Proposed Role During Glycemic Challenges, Arshad M. Khan, Todd A. Ponzio, Graciela Sanchez-Watts, B. Glenn Stanley, Glenn I. Hatton, Alan G. Watts Jul 2007

Catecholaminergic Control Of Mitogen-Activated Protein Kinase Signaling In Paraventricular Neuroendocrine Neurons In Vivo And In Vitro: A Proposed Role During Glycemic Challenges, Arshad M. Khan, Todd A. Ponzio, Graciela Sanchez-Watts, B. Glenn Stanley, Glenn I. Hatton, Alan G. Watts

Arshad M. Khan, Ph.D.

No abstract provided.


Transition-State Variation In Human, Bovine, And Plasmodium Falciparum Adenosine Deaminases, Minkui Lou, Vipender Singh, Erika Taylor, Vern Schramm May 2007

Transition-State Variation In Human, Bovine, And Plasmodium Falciparum Adenosine Deaminases, Minkui Lou, Vipender Singh, Erika Taylor, Vern Schramm

Erika A. Taylor, Ph.D.

Adenosine deaminases (ADAs) from human, bovine, and Plasmodium falciparum sources were analyzed by kinetic isotope effects (KIEs) and shown to have distinct but related transition states. Human adenosine deaminase (HsADA) is present in most mammalian cells and is involved in B- and T-cell development. The ADA from Plasmodium falciparum (PfADA) is essential in this purine auxotroph, and its inhibition is expected to have therapeutic effects for malaria. Therefore, ADA is of continuing interest for inhibitor design. Stable structural mimics of ADA transition states are powerful inhibitors. Here we report the transition-state structures of PfADA, HsADA, and bovine ADA (BtADA) solved …


Acyclic Ribooxacarbenium Ion Mimics As Transition State Analogues Of Human And Malarial Purine Nucleoside Phosphorylases, Erika Taylor, Keith Clinch, Peter Kelly, Lei Li, Gary Evans, Peter Tyler, Vern Schramm Apr 2007

Acyclic Ribooxacarbenium Ion Mimics As Transition State Analogues Of Human And Malarial Purine Nucleoside Phosphorylases, Erika Taylor, Keith Clinch, Peter Kelly, Lei Li, Gary Evans, Peter Tyler, Vern Schramm

Erika A. Taylor, Ph.D.

Transition state analogues of PNP, the Immucillins and DADMe-Immucillins, were designed to match transition state features of bovine and human PNPs, respectively. A third generation of inhibitors has been designed that contain an acyclic iminoalcohol to replace the cyclic mimic of the ribooxacarbenium ion at the transition states of PNPs. The best third generation inhibitor is equivalent to the best inhibitors found in the previous transition state analogues.


Synthesis Of 5‘-Methylthio Coformycins:  Specific Inhibitors For Malarial Adenosine Deaminase, Peter Tyler, Erika Taylor, Richard Froehlich, Vern Schramm Apr 2007

Synthesis Of 5‘-Methylthio Coformycins:  Specific Inhibitors For Malarial Adenosine Deaminase, Peter Tyler, Erika Taylor, Richard Froehlich, Vern Schramm

Erika A. Taylor, Ph.D.

Transition state theory suggests that enzymatic rate acceleration (kcat/knon) is related to the stabilization of the transition state for a given reaction. Chemically stable analogues of a transition state complex are predicted to convert catalytic energy into binding energy. Because transition state stabilization is a function of catalytic efficiency, differences in substrate specificity can be exploited in the design of tight-binding transition state analogue inhibitors. Coformycin and 2‘-deoxycoformycin are natural product transition state analogue inhibitors of adenosine deaminases (ADAs). These compounds mimic the tetrahedral geometry of the ADA transition state and bind with picomolar dissociation constants to enzymes from bovine, …


Neighboring Group Participation In The Transition State Of Human Purine Nucleoside Phosphorylase, Andrew Murkin, Matthew Birck, Agnes Rinaldo-Matthis, Wuxian Shi, Erika Taylor, Steven Almo, Vern Schramm Mar 2007

Neighboring Group Participation In The Transition State Of Human Purine Nucleoside Phosphorylase, Andrew Murkin, Matthew Birck, Agnes Rinaldo-Matthis, Wuxian Shi, Erika Taylor, Steven Almo, Vern Schramm

Erika A. Taylor, Ph.D.

No abstract provided.


Exercise-Mediated Regulation Of Hsp70 Gene Expression Following Exercise Training, C.W. Melling, David Thorp, Kevin Milne, Matthew Krause, Earl Noble Dec 2006

Exercise-Mediated Regulation Of Hsp70 Gene Expression Following Exercise Training, C.W. Melling, David Thorp, Kevin Milne, Matthew Krause, Earl Noble

Jamie Melling

An issue central to understanding the biological benefits associated with regular exercise training is to elucidate the intracellular mechanisms governing exercise-conferred cardioprotection. Heat shock proteins (HSPs), most notably the inducible 70-kDa HSP family member Hsp70, are believed to participate in the protection of the myocardium during cardiovascular stress. Following acute exercise, activation of PKA mediates the suppression of an intermediary protein kinase, ERK1/2, which phosphorylates and suppresses the activation of the heat shock transcription factor 1 (HSF1). However, following exercise training, ERK1/2 has been reported to regulate the transcriptional activation of several genes involved in cell growth and proliferation and …