Malate dehydrogenase in parasitic protozoans: roles in metabolism and potential therapeutic applications.

The role of malate dehydrogenase (MDH) in the metabolism of various medically significant protozoan parasites is reviewed. MDH is an NADH-dependent oxidoreductase that catalyzes interconversion between oxaloacetate and malate, provides metabolic intermediates for both catabolic and anabolic pathways, and can contribute to NAD+/NADH balance in multiple cellular compartments. MDH is present in nearly all organisms; isoforms of MDH from apicomplexans (Plasmodium falciparum, Toxoplasma gondii, Cryptosporidium spp.

Reoperation for Hirschsprung Disease: Two cases of Vanishing Ganglion Cells and Review of the Literature.

Hirschsprung disease (HD) is characterized by circumferential aganglionosis of the rectum with variable proximal bowel involvement. The underlying pathogenesis is due to failure of caudal migration of neural crest cells during pre-natal development, causing functional bowel obstruction. Definitive therapy is surgical resection; however, a subset of patients will require reoperation.

Structure, Function, and Thermodynamics of Lactate Dehydrogenases from Humans and the Malaria Parasite .

Temperature adaptation is ubiquitous among all living organisms, yet the molecular basis for this process remains poorly understood. It can be assumed that for parasite-host systems, the same enzymes found in both organisms respond to the same selection factor (human body temperature) with similar structural changes. Herein, we report the existence of a reversible temperature-dependent structural transition for the glycolytic enzyme lactate dehydrogenase (LDH) from the malaria parasite (pfLDH) and human heart (hhLDH) occurring in the temperature range of human fever.

Triple Isotope Effects Support Concerted Hydride and Proton Transfer and Promoting Vibrations in Human Heart Lactate Dehydrogenase.

Transition path sampling simulations have proposed that human heart lactate dehydrogenase (LDH) employs protein promoting vibrations (PPVs) on the femtosecond (fs) to picosecond (ps) time scale to promote crossing of the chemical barrier. This chemical barrier involves both hydride and proton transfers to pyruvate to form l-lactate, using reduced nicotinamide adenine dinucleotide (NADH) as the cofactor. Here we report experimental evidence from three types of isotope effect experiments that support coupling of the promoting vibrations to barrier crossing and the coincidence of hydride and proton transfer.

Synergistic Biomineralization Phenomena Created by a Combinatorial Nacre Protein Model System.

In the nacre or aragonite layer of the mollusk shell, proteomes that regulate both the early stages of nucleation and nano-to-mesoscale assembly of nacre tablets from mineral nanoparticle precursors exist. Several approaches have been developed to understand protein-associated mechanisms of nacre formation, yet we still lack insight into how protein ensembles or proteomes manage nucleation and crystal growth. To provide additional insights, we have created a proportionally defined combinatorial model consisting of two nacre-associated proteins, C-RING AP7 (shell nacre, Haliotis rufescens) and pseudo-EF hand PFMG1 (oyster pearl nacre, Pinctada fucata), whose individual in vitro mineralization functionalities are well-documented and distinct from one another.

Insect Cell Glycosylation and Its Impact on the Functionality of a Recombinant Intracrystalline Nacre Protein, AP24.

The impacts of glycosylation on biomineralization protein function are largely unknown. This is certainly true for the mollusk shell, where glycosylated intracrystalline proteins such as AP24 (Haliotis rufescens) exist but their functions and the role of glycosylation remain elusive. To assess the effect of glycosylation on protein function, we expressed two recombinant variants of AP24: an unglycosylated bacteria-expressed version (rAP24N) and a glycosylated insect cell-expressed version (rAP24G).

Pif97, a von Willebrand and Peritrophin Biomineralization Protein, Organizes Mineral Nanoparticles and Creates Intracrystalline Nanochambers.

The formation of the mollusk nacre layer involves the assembly and organization of mineral nanoparticles into fracture-toughened mesoscale-sized aragonite tablets that possess intracrystalline nanoporosities. At least one nacre protein family, known as the framework proteome, is strategically located as part of a macromolecular coating around each nacre tablet and is believed to participate in tablet formation. Here, we report new studies of a recombinant form (rPif97) of a unique Japanese pearl oyster (Pinctada fucata) nacre framework biomineralization protein, Pif97.

An oligomeric C-RING nacre protein influences prenucleation events and organizes mineral nanoparticles.

The mollusk shell nacre layer integrates mineral phases with macromolecular components such as intracrystalline proteins. However, the roles performed by intracrystalline proteins in calcium carbonate nucleation and subsequent postnucleation events (e.g.

The intrinsically disordered C-RING biomineralization protein, AP7, creates protein phases that introduce nanopatterning and nanoporosities into mineral crystals.

We report an interesting process whereby the formation of nanoparticle assemblies on and nanoporosities within calcite crystals is directed by an intrinsically disordered C-RING mollusk shell nacre protein, AP7. Under mineralization conditions, AP7 forms protein phases that direct the nucleation of ordered calcite nanoparticles via a repetitive protein phase deposition process onto calcite crystals. These organized nanoparticles are separated by gaps or spaces that become incorporated into the forming bulk crystal as nanoporosities.

A nacre protein, n16.3, self-assembles to form protein oligomers that dimensionally limit and organize mineral deposits.

The mollusk shell is a complex biological material that integrates mineral phases with organic macromolecular components such as proteins. The role of proteins in the formation of the nacre layer (aragonite mineral phase) is poorly understood, particularly with regard to the organization of mineral deposits within the protein extracellular matrix and the identification of which proteins are responsible for this task. We report new experiments that provide insight into the role of the framework nacre protein, n16.