RESUMO
Molecular communication via diffusion (MCvD) expects Brownian motions of the information molecules to transmit information. However, the signal propagation largely depends on the geometric characteristics of the assumed flow model, i.e., the characteristics of the environment, design, and position of the transmitter and receiver, respectively. These characteristics are assumed to be lucid in many ways by either consideration of one-dimensional diffusion, unbounded environment, or constant drift. In reality, diffusion often occurs in blood-vessel-like channels. To this aim, we try to study the effect of the biological environment on channel performance. The Red-Blood Cells (RBCs) found in blood vessels enforces a higher concentration of molecules towards the vessel walls, leading to better reception. Therefore, in this paper we derive an analytical expression of Channel Impulse Response (CIR) for a dispersion-advection-based regime, contemplating the influence of RBCs in the model and considering a point source transmitter and a realistic design of the receiver.
RESUMO
Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is a ubiquitous enzyme involved in glycolysis. It is also referred to as a moonlighting protein as it has many diverse functions like regulation of apoptosis, iron homeostasis, cell-matrix interactions, adherence to human colon etc. apart from its principal role in glycolysis. Lactobacilli are lactic acid bacteria which colonize the human gut and confer various health benefits to humans. In the present study, we have cloned, expressed and purified the GAPDH from Lactobacillus acidophilus to get a recombinant product (r-LaGAPDH) and characterized it. Size exclusion chromatography shows that r-LaGAPDH exists as a tetramer in solution and have a mucin binding and hemagglutination activity indicating carbohydrate like binding adhesion mechanism. Fluorescence spectroscopy studies showed an interaction of r-LaGAPDH with mannose, galactose, N-acetylgalactosamine and N-acetylglucosamine with a Kd of 3.6±0.7×10(-3)M, 4.34±0.09×10(-3)M, 4±0.87×10(-3)M and 3.7±0.28×10(-3)M respectively. We hope that this preliminary data will generate more interest in further elucidation of the roles of GAPDH in the adhesion processes of the bacteria.
Assuntos
Proteínas de Bactérias , Clonagem Molecular , Expressão Gênica , Gliceraldeído-3-Fosfato Desidrogenase (Fosforiladora) , Lactobacillus acidophilus , Mucinas/química , Proteínas de Bactérias/biossíntese , Proteínas de Bactérias/química , Proteínas de Bactérias/genética , Proteínas de Bactérias/isolamento & purificação , Gliceraldeído-3-Fosfato Desidrogenase (Fosforiladora)/biossíntese , Gliceraldeído-3-Fosfato Desidrogenase (Fosforiladora)/química , Gliceraldeído-3-Fosfato Desidrogenase (Fosforiladora)/genética , Gliceraldeído-3-Fosfato Desidrogenase (Fosforiladora)/isolamento & purificação , Humanos , Lactobacillus acidophilus/enzimologia , Lactobacillus acidophilus/genética , Ligação ProteicaRESUMO
Plant lectins and protease inhibitors constitute a class of proteins which plays a crucial role in plant defense. In our continuing investigations on lectins from plants, we have isolated, purified and characterized a protein of about 20 kDa, named PotHg, showing hemagglutination activity from tubers of Indian potato, Solanum tuberosum. De novo sequencing and MS/MS analysis confirmed that the purified protein was a Kunitz-type serine protease inhibitor having two chains (15 kDa and 5 kDa). SDS and native PAGE analysis showed that the protein was glycosylated and was a heterodimer of about 15 and 5 kDa subunits. PotHg agglutinated rabbit erythrocytes with specific activity of 640 H.U./mg which was inhibited by complex sugars like fetuin. PotHg retained hemagglutination activity over a pH range 4-9 and up to 80°C. Mannose and galactose interacted with the PotHg with a dissociation constant (Kd) of 1.5×10(-3) M and 2.8×10(-3) M, respectively as determined through fluorescence studies. Fluorescence studies suggested the involvement of a tryptophan in sugar binding which was further confirmed through modification of tryptophan residues using N-bromosuccinimide. Circular dichroism (CD) studies showed that PotHg contains mostly ß sheets (â¼45%) and loops which is in line with previously characterized protease inhibitors and modeling studies. There are previous reports of Kunitz-type protease inhibitors showing lectin like activity from Peltophorum dubium and Labramia bojeri. This is the first report of a Kunitz-type protease inhibitor showing lectin like activity from a major crop plant and this makes PotHg an interesting candidate for further investigation.